1 00:00:00,030 --> 00:00:02,410 The following content is provided under a Creative 2 00:00:02,410 --> 00:00:03,830 Commons license. 3 00:00:03,830 --> 00:00:06,965 Your support will help MIT OpenCourseWare continue to 4 00:00:06,965 --> 00:00:10,510 offer high-quality educational resources for free. 5 00:00:10,510 --> 00:00:13,400 To make a donation, or view additional materials from 6 00:00:13,400 --> 00:00:17,290 hundreds of MIT courses, visit MIT OpenCourseWare at 7 00:00:17,290 --> 00:00:18,540 ocw.mit.edu. 8 00:00:22,210 --> 00:00:23,040 PROFESSOR: OK. 9 00:00:23,040 --> 00:00:24,130 Perfect timing. 10 00:00:24,130 --> 00:00:28,090 Let's turn to the announcements. 11 00:00:28,090 --> 00:00:30,820 You know the big announcement is Monday, 12 00:00:30,820 --> 00:00:33,110 Celebration Part three. 13 00:00:33,110 --> 00:00:35,610 I think Hilary sent all of you the coverage. 14 00:00:35,610 --> 00:00:39,110 Just to be clear, start with defects, amorphous solids, 15 00:00:39,110 --> 00:00:41,820 kinetics, diffusions, solutions, acids, and bases. 16 00:00:41,820 --> 00:00:44,150 No orgo, no polymers. 17 00:00:44,150 --> 00:00:47,180 We'll catch the orgo and the polymers on the celebration of 18 00:00:47,180 --> 00:00:49,430 celebrations, the final exam. 19 00:00:52,330 --> 00:00:54,250 OK, so let's get moving. 20 00:00:54,250 --> 00:00:56,440 Last day we started talking about polymers. 21 00:00:56,440 --> 00:00:57,990 These are macromolecules. 22 00:00:57,990 --> 00:01:01,950 Here we've got an example of a simple compound with a double 23 00:01:01,950 --> 00:01:03,610 bond, vinyl chloride. 24 00:01:03,610 --> 00:01:08,650 And by the action of addition polymerization, we can turn 25 00:01:08,650 --> 00:01:11,670 this into a macromolecule where you see a repeat unit. 26 00:01:11,670 --> 00:01:15,960 The double bond has been broken to allow but carbon to 27 00:01:15,960 --> 00:01:18,970 bond to another vinyl chloride, and so on. 28 00:01:18,970 --> 00:01:21,530 These are very, very large molecules, can be on the order 29 00:01:21,530 --> 00:01:26,690 of microns in length, mass measured in kilodaltons, or 30 00:01:26,690 --> 00:01:31,290 thousands of grams per mole. 31 00:01:31,290 --> 00:01:33,270 So today I want to go back and look a little 32 00:01:33,270 --> 00:01:34,890 bit at polymer synthesis. 33 00:01:34,890 --> 00:01:37,440 Then we're going to talk about properties of polymers, and 34 00:01:37,440 --> 00:01:40,400 end with some cultural implications that I alluded to 35 00:01:40,400 --> 00:01:41,510 the very beginning. 36 00:01:41,510 --> 00:01:45,780 So we've already seen how this reaction begins, but let's see 37 00:01:45,780 --> 00:01:47,110 how it proceeds. 38 00:01:47,110 --> 00:01:53,230 So here's an example of starting with an initiation 39 00:01:53,230 --> 00:01:57,460 reaction that generates this hydroxyl radical that starts 40 00:01:57,460 --> 00:01:58,780 from a peroxide. 41 00:01:58,780 --> 00:02:02,560 And then you can see, in this first instance, the unpaired 42 00:02:02,560 --> 00:02:05,870 electron attacks the double bond, breaks the double bond 43 00:02:05,870 --> 00:02:08,770 links, and then moves that unpaired electron to the end, 44 00:02:08,770 --> 00:02:10,300 and so on, and so on. 45 00:02:10,300 --> 00:02:14,450 So here I'm indicating that we're going to keep attaching, 46 00:02:14,450 --> 00:02:17,430 in this case, ethylenes to make polyethylene. 47 00:02:17,430 --> 00:02:20,210 And then at some point, we decide that we've got the 48 00:02:20,210 --> 00:02:22,190 molecule long enough, and then we have 49 00:02:22,190 --> 00:02:23,300 to quench the reaction. 50 00:02:23,300 --> 00:02:27,640 So then we add something that will cap this unpaired 51 00:02:27,640 --> 00:02:31,140 electron, and this step is called termination. 52 00:02:31,140 --> 00:02:34,370 So this is how we make the long-chain molecules by this 53 00:02:34,370 --> 00:02:36,910 particular reaction. 54 00:02:36,910 --> 00:02:39,880 And the thing to know, trivially, is that the 55 00:02:39,880 --> 00:02:42,040 composition of the polymer equals the 56 00:02:42,040 --> 00:02:43,150 composition of the mer. 57 00:02:43,150 --> 00:02:44,460 You can see it right here, that I 58 00:02:44,460 --> 00:02:46,090 start with vinyl chloride. 59 00:02:46,090 --> 00:02:48,510 Yeah, we've changed the double bond to a single bond, but 60 00:02:48,510 --> 00:02:54,320 it's still C2H3Cl, C2H3Cl taken many times. 61 00:02:54,320 --> 00:02:55,280 That's it. 62 00:02:55,280 --> 00:02:56,310 OK. 63 00:02:56,310 --> 00:03:00,200 There's another way to make polymers. 64 00:03:00,200 --> 00:03:03,120 And this is really important, not only in commerce, but it's 65 00:03:03,120 --> 00:03:04,890 most important in biology. 66 00:03:04,890 --> 00:03:09,370 We do not have the biological apparatus to create radicals. 67 00:03:09,370 --> 00:03:13,460 So during the course of this lecture, we have cell death 68 00:03:13,460 --> 00:03:15,940 proceeding in all of us, and cell generation and 69 00:03:15,940 --> 00:03:20,080 polymerization reactions occurring, amino acids being 70 00:03:20,080 --> 00:03:22,160 linked to form proteins and whatnot. 71 00:03:22,160 --> 00:03:26,530 And that process goes by the second mechanism, condensation 72 00:03:26,530 --> 00:03:27,780 polymerization. 73 00:03:27,780 --> 00:03:30,940 And I'll give you a simple example of that where we start 74 00:03:30,940 --> 00:03:33,020 with more than one mer, OK? 75 00:03:33,020 --> 00:03:37,670 Involves more than one mer type. 76 00:03:44,160 --> 00:03:45,830 Typically two, all right? 77 00:03:45,830 --> 00:03:48,340 So let's look at a reaction. 78 00:03:48,340 --> 00:03:52,590 So this is going to be a first kind of a mer, and R is just a 79 00:03:52,590 --> 00:03:57,300 general placeholder the people use in organic chemistry. 80 00:03:57,300 --> 00:04:02,300 It comes from the word residual, but it's some giant 81 00:04:02,300 --> 00:04:06,700 piece of molecular mass, and there's a hydrogen here. 82 00:04:06,700 --> 00:04:10,420 And this one then reacts with a second mer, which I'm going 83 00:04:10,420 --> 00:04:12,010 to designate R2. 84 00:04:12,010 --> 00:04:13,360 And the second mer has a hydroxyl. 85 00:04:16,670 --> 00:04:19,440 And what happens in condensation polymerization, 86 00:04:19,440 --> 00:04:25,000 is that we link R1 to R2. 87 00:04:25,000 --> 00:04:29,190 R1 is now linked to R2 in a covalent manner. 88 00:04:29,190 --> 00:04:39,080 And then, we take the hydrogen and the hydroxyl, and we send 89 00:04:39,080 --> 00:04:40,580 them over here. 90 00:04:40,580 --> 00:04:43,910 So the hydrogen goes here, the hydroxyl goes 91 00:04:43,910 --> 00:04:49,540 here, to form water. 92 00:04:49,540 --> 00:04:53,460 And this is typically conducted, in industry, not in 93 00:04:53,460 --> 00:04:56,170 our bodies, but in industry, it's typically conducted at 94 00:04:56,170 --> 00:05:00,240 elevated temperatures where this eventually goes into some 95 00:05:00,240 --> 00:05:01,490 kind of a condenser. 96 00:05:04,340 --> 00:05:07,590 And then the water condenses and makes liquid. 97 00:05:07,590 --> 00:05:12,000 And for this step, the condensation step of the 98 00:05:12,000 --> 00:05:15,810 byproduct of the reaction that we name the process. 99 00:05:15,810 --> 00:05:18,390 The process isn't named for what happens here. 100 00:05:18,390 --> 00:05:19,960 It's named for what happens over here. 101 00:05:19,960 --> 00:05:22,690 So this is condensation polymerization, and you can 102 00:05:22,690 --> 00:05:25,900 see, we have covalent linkages at both ends, and we can add 103 00:05:25,900 --> 00:05:30,940 another R1H here, and then another R2OH here, and so on, 104 00:05:30,940 --> 00:05:32,520 and so on, and so on. 105 00:05:32,520 --> 00:05:36,220 So clearly, we're losing some of the mass of 106 00:05:36,220 --> 00:05:38,520 the reactants here. 107 00:05:38,520 --> 00:05:43,200 So the mass of the final polymer is less than the sum 108 00:05:43,200 --> 00:05:47,080 of the masses of all of the reagents. 109 00:05:47,080 --> 00:05:48,320 So let's make a note of that. 110 00:05:48,320 --> 00:05:54,770 That the mass of the polymer formed by condensation 111 00:05:54,770 --> 00:06:01,730 polymerization is less than the sum of the masses of the 112 00:06:01,730 --> 00:06:04,180 constituents. 113 00:06:04,180 --> 00:06:06,670 Or let's say reactants, if we like. 114 00:06:06,670 --> 00:06:08,890 Reactants. 115 00:06:08,890 --> 00:06:10,140 Because we lose the condensate. 116 00:06:12,790 --> 00:06:19,310 And so here's an example from commerce. 117 00:06:19,310 --> 00:06:22,540 Oh, before I get to that, I wanted to show you some of the 118 00:06:22,540 --> 00:06:25,600 common addition polymers, which ones that you're 119 00:06:25,600 --> 00:06:28,440 familiar with that are made by this first process. 120 00:06:28,440 --> 00:06:29,900 So at the top, we have polyethylene. 121 00:06:29,900 --> 00:06:31,400 That's we started with. 122 00:06:31,400 --> 00:06:36,580 And you know that's used in food wrap, it's used in milk 123 00:06:36,580 --> 00:06:37,810 jugs, and so on. 124 00:06:37,810 --> 00:06:40,340 There's the polytetrafluoroethylene. 125 00:06:40,340 --> 00:06:43,030 You remove the hydrogens, you put fluorines, and then you 126 00:06:43,030 --> 00:06:44,190 make Teflon. 127 00:06:44,190 --> 00:06:45,740 So that's also made by addition. 128 00:06:45,740 --> 00:06:48,635 Polypropylene, also used as separator. 129 00:06:48,635 --> 00:06:50,910 In fact, polypropylene is found in 130 00:06:50,910 --> 00:06:52,130 every lithium ion battery. 131 00:06:52,130 --> 00:06:55,060 It's the separator between the two electrodes, and it's 132 00:06:55,060 --> 00:06:58,760 engineered so that its glass transition temperature is 133 00:06:58,760 --> 00:07:02,160 about 60, 70 degrees Celsius. 134 00:07:02,160 --> 00:07:05,010 So that if there's some event, and you start getting thermal 135 00:07:05,010 --> 00:07:08,050 runaway in your battery, and the temperature rises to 136 00:07:08,050 --> 00:07:11,670 whatever, let's say the number is 70 degrees C, the pores in 137 00:07:11,670 --> 00:07:14,150 the polypropylene collapse. 138 00:07:14,150 --> 00:07:17,380 And when they collapse, they form a barrier, and it kills 139 00:07:17,380 --> 00:07:20,450 the battery, and prevents the battery from exploding. 140 00:07:20,450 --> 00:07:23,550 And that's polypropylene. 141 00:07:23,550 --> 00:07:25,720 There's butyl rubber. 142 00:07:25,720 --> 00:07:26,320 What else do we have? 143 00:07:26,320 --> 00:07:32,610 Polystyrene, you know, which is used in these cups and food 144 00:07:32,610 --> 00:07:34,080 containers. 145 00:07:34,080 --> 00:07:34,920 Orlon, here. 146 00:07:34,920 --> 00:07:38,280 Polyvinyl chloride, which is used in everything from old 147 00:07:38,280 --> 00:07:42,180 vinyl phonograph records to plumbing supplies. 148 00:07:42,180 --> 00:07:46,610 That white PVC tubing that's used for piping. 149 00:07:46,610 --> 00:07:49,610 Polymethyl methacrylate, this is plexiglass, which many of 150 00:07:49,610 --> 00:07:51,170 you are wearing in your eyeglasses. 151 00:07:51,170 --> 00:07:54,530 That's this material here. 152 00:07:54,530 --> 00:07:55,860 Butadiene, OK. 153 00:07:55,860 --> 00:07:59,140 You see there's the after-polymerization. 154 00:07:59,140 --> 00:08:03,450 There's still one unused double bond, so then we can 155 00:08:03,450 --> 00:08:07,070 mix this later on for cross-linking. 156 00:08:07,070 --> 00:08:08,630 And the various rubbers, and so on. 157 00:08:08,630 --> 00:08:11,210 You can see, they all have residual double bonds, which 158 00:08:11,210 --> 00:08:12,770 allows them to then participate 159 00:08:12,770 --> 00:08:15,460 in disulfide linkages. 160 00:08:15,460 --> 00:08:15,770 OK. 161 00:08:15,770 --> 00:08:18,240 So now here's the example I wanted to show you that you 162 00:08:18,240 --> 00:08:20,040 will be familiar with in commerce. 163 00:08:20,040 --> 00:08:22,910 This is the PET, the polyethylene terephthalate, 164 00:08:22,910 --> 00:08:25,260 the plastic bottles. 165 00:08:25,260 --> 00:08:27,640 The two-liter soda bottles are made of this stuff. 166 00:08:27,640 --> 00:08:30,570 So you start with this thing, which is known industrially as 167 00:08:30,570 --> 00:08:33,730 terephthalic acid, which is really 1-4-benzene. 168 00:08:33,730 --> 00:08:36,600 You see the benzene ring here, so one, two, three, four. 169 00:08:36,600 --> 00:08:39,850 So off the one position and the four position, you have a 170 00:08:39,850 --> 00:08:43,420 carboxylic acid, and this is critical in proteins. 171 00:08:43,420 --> 00:08:47,710 You're going to see the COOH structure over and over again. 172 00:08:47,710 --> 00:08:51,110 And that H is detachable. 173 00:08:51,110 --> 00:08:53,660 So this, then, it becomes a proton donor. 174 00:08:53,660 --> 00:08:55,820 If it's a proton donor, it's an acid. 175 00:08:55,820 --> 00:09:00,210 So this is the 1-4-benzenedicarboxylic acid. 176 00:09:00,210 --> 00:09:03,240 And this is ethylene glycol, which you know as the base 177 00:09:03,240 --> 00:09:06,150 constituent of antifreeze for automobiles. 178 00:09:06,150 --> 00:09:09,480 It's really ethane with two alcohols. 179 00:09:09,480 --> 00:09:10,670 So it's a diol. 180 00:09:10,670 --> 00:09:12,630 Ethanediol, 1-2. 181 00:09:12,630 --> 00:09:17,440 And you mix the ethanediol with the terephthalic acid, 182 00:09:17,440 --> 00:09:21,700 spit off the proton and the hydroxyl, leaving behind this, 183 00:09:21,700 --> 00:09:24,480 which then forms the bridge here, and there's the basis 184 00:09:24,480 --> 00:09:26,720 for the plastic soda bottle. 185 00:09:26,720 --> 00:09:30,140 This is the same material from which you can make Dacron, 186 00:09:30,140 --> 00:09:34,290 which is a fiber used sometimes in textiles, and 187 00:09:34,290 --> 00:09:39,205 Mylar, which is used in sheet films for polymer films. So 188 00:09:39,205 --> 00:09:40,580 this is the PET. 189 00:09:40,580 --> 00:09:44,770 And note here, you see this oxygen is acting as a bridge. 190 00:09:44,770 --> 00:09:47,400 It's acting as a bridge between the terephthalic acid 191 00:09:47,400 --> 00:09:50,430 residual and the ethylene glycol residual. 192 00:09:50,430 --> 00:09:53,430 So again, we see nature relying on the fact that 193 00:09:53,430 --> 00:09:59,230 oxygen forms those two bonds and acts as a bridge for us. 194 00:09:59,230 --> 00:10:00,780 OK. 195 00:10:00,780 --> 00:10:03,570 A couple of other things to note. 196 00:10:03,570 --> 00:10:08,390 Here are the typical polymers that are made by condensation 197 00:10:08,390 --> 00:10:09,040 polymerization. 198 00:10:09,040 --> 00:10:10,610 All of the nylons. 199 00:10:10,610 --> 00:10:14,750 The nylons are made by condensation polymerization. 200 00:10:14,750 --> 00:10:20,360 And the bond here that exists between the nitrogen and the 201 00:10:20,360 --> 00:10:22,390 carbon is called the amide bond. 202 00:10:22,390 --> 00:10:26,410 Even though it's spelled A M I D E, it's pronounced amid. 203 00:10:26,410 --> 00:10:27,680 So these are all nylons. 204 00:10:27,680 --> 00:10:29,810 The generic term is polyamides. 205 00:10:29,810 --> 00:10:33,180 And you see the different types of nylon here. 206 00:10:33,180 --> 00:10:38,690 Kevlar, used as a substitute for steel belting in tires, 207 00:10:38,690 --> 00:10:41,910 derives its strength from this, the benzene ring here. 208 00:10:41,910 --> 00:10:44,150 And polyesters, OK? 209 00:10:44,150 --> 00:10:46,610 The Dacron, the Mylar, I just showed you that. 210 00:10:46,610 --> 00:10:47,480 Lexan. 211 00:10:47,480 --> 00:10:51,320 This is used in everything from sports equipment, if you 212 00:10:51,320 --> 00:10:55,080 wear eyeglasses in sports, they're 213 00:10:55,080 --> 00:10:56,910 probably made of Lexan. 214 00:10:56,910 --> 00:11:00,820 Again, look at these twin benzene rings, and then you've 215 00:11:00,820 --> 00:11:03,250 got the linkage on the end here. 216 00:11:03,250 --> 00:11:06,270 And also used when you're sitting seven miles above the 217 00:11:06,270 --> 00:11:07,100 surface of the earth. 218 00:11:07,100 --> 00:11:10,460 The only thing that prevents you from being asphyxiated or 219 00:11:10,460 --> 00:11:12,760 frozen to death in that airplane is a 220 00:11:12,760 --> 00:11:15,010 window made of Lexan. 221 00:11:15,010 --> 00:11:18,990 And lastly, here are the silicones, which are also made 222 00:11:18,990 --> 00:11:20,805 by condensation polymerization. 223 00:11:20,805 --> 00:11:23,590 And just a little note here for you. 224 00:11:23,590 --> 00:11:26,910 The person who invented the silicones 225 00:11:26,910 --> 00:11:28,070 didn't know his chemistry. 226 00:11:28,070 --> 00:11:30,410 And he thought that the silicone, in fact, had a 227 00:11:30,410 --> 00:11:31,200 double bond here. 228 00:11:31,200 --> 00:11:33,960 See, this is acetone, and it from comes from 229 00:11:33,960 --> 00:11:35,620 the family of ketones. 230 00:11:35,620 --> 00:11:38,840 So you have methyl above, methyl below, carbon, and a 231 00:11:38,840 --> 00:11:40,220 double bond off to the side. 232 00:11:40,220 --> 00:11:41,970 Well, it turns out that silicone 233 00:11:41,970 --> 00:11:43,420 doesn't form double bonds. 234 00:11:43,420 --> 00:11:45,460 Everybody in 3.091 knows this. 235 00:11:45,460 --> 00:11:46,750 It's too big. 236 00:11:46,750 --> 00:11:48,220 So it only has a single bond. 237 00:11:48,220 --> 00:11:50,730 If it's a single bond, it's not an -one. 238 00:11:50,730 --> 00:11:54,830 It's just like a pentane, methane, so on. 239 00:11:54,830 --> 00:11:57,060 So this should be a siloxane. 240 00:11:57,060 --> 00:12:00,630 So what people refer to as silicones today properly are 241 00:12:00,630 --> 00:12:03,270 called siloxanes. 242 00:12:03,270 --> 00:12:03,680 OK. 243 00:12:03,680 --> 00:12:05,260 Another thing to note. 244 00:12:05,260 --> 00:12:08,010 Let's go back to the-- 245 00:12:08,010 --> 00:12:09,820 you see here? 246 00:12:09,820 --> 00:12:13,170 We go down the backbone of the nylon, there's 247 00:12:13,170 --> 00:12:14,450 the carboxylic acid. 248 00:12:14,450 --> 00:12:18,080 And there's a C with a double bond to the O, and it spit off 249 00:12:18,080 --> 00:12:19,100 its H, right? 250 00:12:19,100 --> 00:12:20,610 That was the proton donor. 251 00:12:20,610 --> 00:12:21,590 Look at over here. 252 00:12:21,590 --> 00:12:25,100 There's an amino group here, a nitrogen with a hydrogen. 253 00:12:25,100 --> 00:12:27,720 Well, if I line those two up just right, 254 00:12:27,720 --> 00:12:29,100 look at what can happen. 255 00:12:29,100 --> 00:12:32,270 Here's a carbon-oxygen, and here's a nitrogen-hydrogen. 256 00:12:32,270 --> 00:12:34,060 What do you know if you've got hydrogen 257 00:12:34,060 --> 00:12:35,950 sitting next to an oxygen? 258 00:12:35,950 --> 00:12:37,920 It can form hydrogen bonds. 259 00:12:37,920 --> 00:12:42,590 And so nylons derive their higher strength from the 260 00:12:42,590 --> 00:12:45,950 hydrogen bonds that form between the chains. 261 00:12:45,950 --> 00:12:48,670 Doesn't this remind you of cross-linking? 262 00:12:48,670 --> 00:12:50,550 It's sort of same church, different pew. 263 00:12:50,550 --> 00:12:54,470 It's not as strong as a disulfite covalent linkage, 264 00:12:54,470 --> 00:12:56,950 but it does form linkages. 265 00:12:56,950 --> 00:12:58,320 That's good. 266 00:12:58,320 --> 00:13:00,400 It's good because it gives you strength. 267 00:13:00,400 --> 00:13:03,780 But it doesn't come with the penalty that cross-linking 268 00:13:03,780 --> 00:13:04,820 comes with. 269 00:13:04,820 --> 00:13:05,980 And what's the penalty? 270 00:13:05,980 --> 00:13:09,370 You can't recycle cross- linked polymers very easily, 271 00:13:09,370 --> 00:13:12,650 because you've got these strong covalent 272 00:13:12,650 --> 00:13:13,750 bonds in the chains. 273 00:13:13,750 --> 00:13:16,750 If you heat the polymer up, those bonds don't break. 274 00:13:16,750 --> 00:13:20,300 If you heat this up, the hydrogen bonds will let go. 275 00:13:20,300 --> 00:13:23,930 And you can remelt nylons, you can recycle those polymers 276 00:13:23,930 --> 00:13:25,260 much more easily. 277 00:13:25,260 --> 00:13:28,850 So I want to make another taxonomy here that 278 00:13:28,850 --> 00:13:31,810 distinguishes polymers on the basis of their 279 00:13:31,810 --> 00:13:33,920 ability to be recycled. 280 00:13:33,920 --> 00:13:36,070 Very important these days. 281 00:13:36,070 --> 00:13:38,620 One of the first questions people ask if you're using a 282 00:13:38,620 --> 00:13:41,890 polymer in a process, is it recyclable? 283 00:13:41,890 --> 00:13:43,110 And what do you do? 284 00:13:43,110 --> 00:13:45,750 You start thinking about the molecular architecture in 285 00:13:45,750 --> 00:13:47,880 order to answer that question. 286 00:13:47,880 --> 00:13:48,210 OK. 287 00:13:48,210 --> 00:13:51,760 So let's talk about the ones that can be recycled. 288 00:13:51,760 --> 00:13:54,125 So recyclable ones are called thermoplastics. 289 00:14:01,040 --> 00:14:08,960 Weak van der Waals and hydrogen bonds only. 290 00:14:08,960 --> 00:14:10,130 And this is between the chains. 291 00:14:10,130 --> 00:14:12,750 You don't break the bonds up and down the backbone. 292 00:14:12,750 --> 00:14:14,620 If you break the blinds up and down the backbone, you'll 293 00:14:14,620 --> 00:14:15,910 pyrolyze the material. 294 00:14:15,910 --> 00:14:18,440 If you go to a high enough temperature to break covalent 295 00:14:18,440 --> 00:14:22,790 bonds in the backbone of a polymer, you're on fire. 296 00:14:22,790 --> 00:14:24,300 So don't go there, all right? 297 00:14:24,300 --> 00:14:29,710 So hydrogen bonds only, so this can reheat and reprocess. 298 00:14:33,610 --> 00:14:35,810 So now we're talking about something that's almost like 299 00:14:35,810 --> 00:14:36,980 recycling metal. 300 00:14:36,980 --> 00:14:39,300 You remelt it and reuse it. 301 00:14:39,300 --> 00:14:42,930 The ones that have the strong covalent linkages are called 302 00:14:42,930 --> 00:14:44,180 thermal sets. 303 00:14:47,170 --> 00:14:49,690 And the thermal set is difficult to recycle. 304 00:14:49,690 --> 00:14:50,940 This is cross-linked-- 305 00:14:54,460 --> 00:14:55,740 difficult. 306 00:14:55,740 --> 00:14:57,840 Notice I'm not writing impossible. 307 00:14:57,840 --> 00:15:00,570 It's difficult to recycle, which is a polite way of 308 00:15:00,570 --> 00:15:02,380 saying, you can do it, and it's really 309 00:15:02,380 --> 00:15:03,840 expensive to do so. 310 00:15:03,840 --> 00:15:05,070 You might be better off to just 311 00:15:05,070 --> 00:15:06,990 start with virgin material. 312 00:15:06,990 --> 00:15:09,410 By the way, where do we get the material? 313 00:15:09,410 --> 00:15:10,500 How do we make polymers? 314 00:15:10,500 --> 00:15:12,890 Where do we get this carbon from? 315 00:15:12,890 --> 00:15:16,420 From petroleum. 316 00:15:16,420 --> 00:15:18,220 You say, well, why don't we use coal? 317 00:15:18,220 --> 00:15:22,170 Well, you need carbon and hydrogen in these systems. And 318 00:15:22,170 --> 00:15:23,460 coal is carbon. 319 00:15:23,460 --> 00:15:25,240 Petroleum is hydrocarbon. 320 00:15:25,240 --> 00:15:27,050 So these are petroleum-derived. 321 00:15:27,050 --> 00:15:30,630 So all these questions about resource utilization and so on 322 00:15:30,630 --> 00:15:33,210 come right up in center stage. 323 00:15:33,210 --> 00:15:33,470 OK. 324 00:15:33,470 --> 00:15:36,950 Now I want to take a few minutes to talk about use of 325 00:15:36,950 --> 00:15:39,720 crystallization to strengthen polymers, OK? 326 00:15:39,720 --> 00:15:48,440 So crystallization for mechanical performance. 327 00:15:51,210 --> 00:15:53,350 We want to improve the mechanical performance. 328 00:15:53,350 --> 00:15:54,500 And I alluded to this last day. 329 00:15:54,500 --> 00:15:55,740 We;ll do this really quickly. 330 00:15:55,740 --> 00:16:01,050 So we've seen that if we want to, we know that if we-- 331 00:16:01,050 --> 00:16:02,430 let me give you the little icon here. 332 00:16:02,430 --> 00:16:06,630 So you're going along like this, and some nice, long 333 00:16:06,630 --> 00:16:08,490 chain, and all of a sudden, you get a zone of 334 00:16:08,490 --> 00:16:09,660 crystallinity. 335 00:16:09,660 --> 00:16:14,390 So I'm talking about adding crystallinity in order to 336 00:16:14,390 --> 00:16:15,360 strengthen the material. 337 00:16:15,360 --> 00:16:19,820 And so we know that this has more bond density than the 338 00:16:19,820 --> 00:16:22,610 straight chain here, so this is going to be stronger. 339 00:16:22,610 --> 00:16:25,270 So if I want to strengthen the polymer, introduce more 340 00:16:25,270 --> 00:16:30,230 crystallization, so what favors the onset of 341 00:16:30,230 --> 00:16:31,110 crystallization? 342 00:16:31,110 --> 00:16:32,850 Or we'll say, partial crystallization. 343 00:16:32,850 --> 00:16:34,870 The whole thing doesn't turn into a crystal. 344 00:16:34,870 --> 00:16:39,500 To favor crystallization, what do we do with the various set 345 00:16:39,500 --> 00:16:41,370 points that we have in the material? 346 00:16:41,370 --> 00:16:45,770 Well, first of all, we know with composition, composition 347 00:16:45,770 --> 00:16:47,380 is one of our levers. 348 00:16:47,380 --> 00:16:48,630 And we want to make it uniform. 349 00:16:51,120 --> 00:16:58,930 So that means homopolymer is favored over the copolymer. 350 00:17:02,740 --> 00:17:05,260 Or maybe there are other instances where you don't want 351 00:17:05,260 --> 00:17:05,990 crystallinity. 352 00:17:05,990 --> 00:17:08,420 In the soles of your running shoe, you don't want that 353 00:17:08,420 --> 00:17:10,620 turning into something that's semibrittle. 354 00:17:10,620 --> 00:17:11,640 You want it to be soft. 355 00:17:11,640 --> 00:17:14,000 So that's why we use copolymers in the soles of 356 00:17:14,000 --> 00:17:17,930 running shoes, in order to disfavor. 357 00:17:17,930 --> 00:17:21,000 And if we want to do something like those jewel cases that I 358 00:17:21,000 --> 00:17:24,280 keep railing against, the jewel cases are a homopolymer 359 00:17:24,280 --> 00:17:29,630 that have a fair bit of crystallinity. 360 00:17:29,630 --> 00:17:33,240 The second one we talked about last day, tacticity, this is a 361 00:17:33,240 --> 00:17:36,620 second lever that you have. So we know that 362 00:17:36,620 --> 00:17:45,285 isotactic over atactic. 363 00:17:45,285 --> 00:17:48,660 The more uniform, the more likely the material will be to 364 00:17:48,660 --> 00:17:49,260 crystallize. 365 00:17:49,260 --> 00:17:52,790 So the isotactic polystyrene makes those jewel boxes, 366 00:17:52,790 --> 00:17:56,490 whereas the atactic polystyrene makes the food 367 00:17:56,490 --> 00:17:58,580 containers that you get when you buy food from 368 00:17:58,580 --> 00:18:00,550 the trucks out here. 369 00:18:00,550 --> 00:18:02,440 And number three, we talked about conformation. 370 00:18:05,460 --> 00:18:07,140 And we know that conformation-- 371 00:18:07,140 --> 00:18:09,500 linear over branched, right? 372 00:18:09,500 --> 00:18:11,890 Linear over branched. 373 00:18:11,890 --> 00:18:15,860 If we have a branched polymer, it's not going to pack very 374 00:18:15,860 --> 00:18:18,410 well, so it's less likely to crystallize. 375 00:18:18,410 --> 00:18:21,170 The linear one, as I've demonstrated in this cartoon, 376 00:18:21,170 --> 00:18:23,850 has a much, much higher propensity for 377 00:18:23,850 --> 00:18:25,160 crystallization. 378 00:18:25,160 --> 00:18:25,390 All right. 379 00:18:25,390 --> 00:18:26,490 How about properties? 380 00:18:26,490 --> 00:18:29,440 Let's talk about properties. 381 00:18:29,440 --> 00:18:32,450 Properties of polymers. 382 00:18:32,450 --> 00:18:36,790 And I'm talking here about the bulk commodity polymers. 383 00:18:36,790 --> 00:18:40,630 Sure, you can find specialty polymers that have remarkable 384 00:18:40,630 --> 00:18:42,910 properties that aren't characteristic of polymers, 385 00:18:42,910 --> 00:18:44,040 but I'm not talking about those. 386 00:18:44,040 --> 00:18:45,640 So first of all. 387 00:18:45,640 --> 00:18:46,740 Electrical properties. 388 00:18:46,740 --> 00:18:49,660 They're insulators, electrical insulators. 389 00:18:49,660 --> 00:18:52,160 Why are they electrical insulators? 390 00:18:52,160 --> 00:18:54,970 We're talking about mainly covalent bonds here. 391 00:18:54,970 --> 00:18:59,630 Covalent bonds, which means tightly bound electrons, 392 00:18:59,630 --> 00:19:03,080 tightly bound and localized, because you saw that in 393 00:19:03,080 --> 00:19:05,220 graphite, they're tightly bound, but they're 394 00:19:05,220 --> 00:19:06,080 delocalized. 395 00:19:06,080 --> 00:19:08,090 So tightly bound electrons. 396 00:19:08,090 --> 00:19:11,230 And no ions, because we've now recognized that we can conduct 397 00:19:11,230 --> 00:19:14,070 electricity not only by electrons, but by ions. 398 00:19:14,070 --> 00:19:17,355 Tightly bound electrons, no ions. 399 00:19:17,355 --> 00:19:21,520 That means no carriers, that means no connectivity. 400 00:19:21,520 --> 00:19:22,290 Number two. 401 00:19:22,290 --> 00:19:24,320 What's the second property? 402 00:19:24,320 --> 00:19:25,790 Transparent to visible light. 403 00:19:32,790 --> 00:19:33,780 Again, same thing. 404 00:19:33,780 --> 00:19:38,880 Tightly bound electrons, not possible to excite, et cetera. 405 00:19:38,880 --> 00:19:42,250 So these are clear, and furthermore, 406 00:19:42,250 --> 00:19:44,800 are generally colorless. 407 00:19:47,410 --> 00:19:52,760 And this is especially in the case of amorphous materials. 408 00:19:52,760 --> 00:19:55,700 Amorphous materials are clear, colorless. 409 00:19:55,700 --> 00:19:58,290 What happens if we get semicrystallization? 410 00:19:58,290 --> 00:20:01,250 Those crystalline zones, as I showed you last day, those 411 00:20:01,250 --> 00:20:04,950 crystalline zones are clear and colorless as well, but the 412 00:20:04,950 --> 00:20:08,880 index of refraction of the crystalline zone is not equal 413 00:20:08,880 --> 00:20:12,300 to the index of refraction of the amorphous zone, and so 414 00:20:12,300 --> 00:20:16,110 this boundary, if you will, scatters light. 415 00:20:16,110 --> 00:20:18,550 So we have two clear and colorless zones of different 416 00:20:18,550 --> 00:20:22,820 index, and so if we put them together, we end up with 417 00:20:22,820 --> 00:20:29,880 something that is opaque, and that's in the case of the 418 00:20:29,880 --> 00:20:30,760 crystallinity. 419 00:20:30,760 --> 00:20:32,040 When you have some crystallinity, 420 00:20:32,040 --> 00:20:33,690 you'll give up on that. 421 00:20:33,690 --> 00:20:36,540 And actually, I wanted to show you a few things from the 422 00:20:36,540 --> 00:20:37,430 popular culture. 423 00:20:37,430 --> 00:20:39,450 So I think what I've got here-- 424 00:20:39,450 --> 00:20:40,965 oh, these are the-- yeah, OK. 425 00:20:44,370 --> 00:20:47,486 This is a little scene from the musical Chicago. 426 00:20:47,486 --> 00:20:48,920 It's Mr. Cellophane. 427 00:20:48,920 --> 00:20:50,820 Cellophane is polymer, viscose. 428 00:20:50,820 --> 00:20:51,960 All right? 429 00:20:51,960 --> 00:20:52,970 Listen to the properties. 430 00:20:52,970 --> 00:20:54,269 They get it right. 431 00:20:54,269 --> 00:20:54,748 [MUSIC PLAYBACK] 432 00:20:54,748 --> 00:21:03,871 -I tell you Cellophane, Mr. Cellophane, should I bend my 433 00:21:03,871 --> 00:21:07,535 name, Mr. Cellophane. 434 00:21:07,535 --> 00:21:14,518 Because you can look right through me, walk right by me, 435 00:21:14,518 --> 00:21:16,110 and never know I'm there. 436 00:21:19,220 --> 00:21:22,926 -Oh, I didn't see you. 437 00:21:22,926 --> 00:21:23,390 [END MUSIC PLAYBACK] 438 00:21:23,390 --> 00:21:23,710 PROFESSOR: OK. 439 00:21:23,710 --> 00:21:26,890 So sometimes the popular culture gets it right. 440 00:21:26,890 --> 00:21:27,210 All right. 441 00:21:27,210 --> 00:21:30,200 So now, what's the third property of polymers? 442 00:21:30,200 --> 00:21:31,450 Chemically inert. 443 00:21:33,810 --> 00:21:37,820 And this is why we use them in food packaging, and also in 444 00:21:37,820 --> 00:21:40,110 other forms of packaging. 445 00:21:40,110 --> 00:21:45,590 Again, strong bonds, strong covalent bonds, means that 446 00:21:45,590 --> 00:21:50,900 it's not very reactive with the contents of many 447 00:21:50,900 --> 00:21:53,670 containers, including foods and beverages. 448 00:21:53,670 --> 00:21:57,560 A fourth property that's exploited in polymers is very 449 00:21:57,560 --> 00:22:00,510 low density. 450 00:22:00,510 --> 00:22:01,520 Why? 451 00:22:01,520 --> 00:22:04,290 Well, what are the constituents of the polymers? 452 00:22:04,290 --> 00:22:06,970 Contains things like carbon, nitrogen-- 453 00:22:06,970 --> 00:22:09,170 well, let's put carbon and hydrogen first. Those are the 454 00:22:09,170 --> 00:22:10,700 two biggies. 455 00:22:10,700 --> 00:22:14,390 So we've got carbon and hydrogen. 456 00:22:14,390 --> 00:22:18,020 You saw some nitrogen, oxygen, and then trace levels of other 457 00:22:18,020 --> 00:22:18,670 substances. 458 00:22:18,670 --> 00:22:23,530 So these are all low Z elements. 459 00:22:23,530 --> 00:22:26,740 So for example, in a beverage container. 460 00:22:26,740 --> 00:22:29,270 I can make a beverage container. 461 00:22:29,270 --> 00:22:30,810 You see a beverage container. 462 00:22:30,810 --> 00:22:33,340 I see a bundle of properties. 463 00:22:33,340 --> 00:22:34,930 What is the bundle of properties? 464 00:22:34,930 --> 00:22:38,510 It has to be some physical rigidity, but not much, 465 00:22:38,510 --> 00:22:39,490 because I can squeeze this. 466 00:22:39,490 --> 00:22:41,170 It's OK. 467 00:22:41,170 --> 00:22:42,720 And it has to be chemically inert with 468 00:22:42,720 --> 00:22:45,470 respect to its contents. 469 00:22:45,470 --> 00:22:48,560 So I could build this out of a borosilicate 470 00:22:48,560 --> 00:22:50,670 glass, a glass bottle. 471 00:22:50,670 --> 00:22:52,210 And the density of borosilicate 472 00:22:52,210 --> 00:22:56,350 glass is about 3.54. 473 00:22:56,350 --> 00:22:58,470 Or I can make it out of aluminum, and the density of 474 00:22:58,470 --> 00:23:01,270 the aluminum is about 2.7. 475 00:23:01,270 --> 00:23:03,340 Or I can make it out of polymer, and the density is 476 00:23:03,340 --> 00:23:05,270 down close to 1. 477 00:23:05,270 --> 00:23:09,250 So now if I load up the beverage truck, instead of 478 00:23:09,250 --> 00:23:14,530 transporting the contents plus the mass of the container, the 479 00:23:14,530 --> 00:23:17,880 higher fraction now is just the contents, and the 480 00:23:17,880 --> 00:23:19,630 container weighs less. 481 00:23:19,630 --> 00:23:22,760 When I was your age, we had still soda 482 00:23:22,760 --> 00:23:24,770 cans made out of steel. 483 00:23:24,770 --> 00:23:26,640 Steel soda cans. 484 00:23:26,640 --> 00:23:26,810 Yeah. 485 00:23:26,810 --> 00:23:27,980 They didn't have pull tops. 486 00:23:27,980 --> 00:23:30,850 You had to have an opener to open them. 487 00:23:30,850 --> 00:23:35,230 And the density of steel is 7.87. 488 00:23:35,230 --> 00:23:36,765 Iron is 7.87. 489 00:23:36,765 --> 00:23:39,050 So from steel, down to this, down to this, and so on. 490 00:23:39,050 --> 00:23:44,880 So you see the low density has an advantage. 491 00:23:44,880 --> 00:23:47,730 But, you know, we're going to have to go back over here and 492 00:23:47,730 --> 00:23:51,900 start thinking about recyclability. 493 00:23:51,900 --> 00:23:56,930 So you see the balancing act here in choosing materials. 494 00:23:56,930 --> 00:24:00,150 You can't just seize upon one attribute and say, oh, this is 495 00:24:00,150 --> 00:24:02,550 less dense than that, let's go with it. 496 00:24:02,550 --> 00:24:05,190 But it's made from petroleum, and maybe it's not so 497 00:24:05,190 --> 00:24:06,780 recyclable. 498 00:24:06,780 --> 00:24:07,740 So now what do you do? 499 00:24:07,740 --> 00:24:10,490 Maybe you do make it out of steel, because you know, what 500 00:24:10,490 --> 00:24:11,950 you can recycle steel. 501 00:24:11,950 --> 00:24:16,510 You can take the door off a 1928 Model-T Ford, melt that 502 00:24:16,510 --> 00:24:21,590 door down, and you can put it on a 2010 Taurus. 503 00:24:21,590 --> 00:24:25,440 That's how recyclable iron is. 504 00:24:25,440 --> 00:24:27,090 I'm just telling you what the properties are. 505 00:24:27,090 --> 00:24:30,200 You're going to have to make the tough decisions. 506 00:24:30,200 --> 00:24:32,373 And five, solid at room temperature. 507 00:24:35,920 --> 00:24:37,950 And why are they solid at room temperature? 508 00:24:37,950 --> 00:24:43,110 Because the interchain bonds, even though they're weak, they 509 00:24:43,110 --> 00:24:46,480 have a long, long, long, long surface contact area. 510 00:24:46,480 --> 00:24:54,800 So entanglement of van der Waals bonds. 511 00:24:54,800 --> 00:24:56,280 So you have the best of both worlds. 512 00:24:56,280 --> 00:24:58,380 It's solid at room temperature, but in the case 513 00:24:58,380 --> 00:25:03,630 of a thermal plastic with modest heating, you can 514 00:25:03,630 --> 00:25:07,510 restore back to the original case. 515 00:25:07,510 --> 00:25:07,970 Oh. 516 00:25:07,970 --> 00:25:10,400 Here I have, I found the Polythene Pam. 517 00:25:10,400 --> 00:25:12,240 I'll play you just a little segment of 518 00:25:12,240 --> 00:25:13,430 it, the first verse. 519 00:25:13,430 --> 00:25:16,020 The interesting thing to listen to, in many of the 520 00:25:16,020 --> 00:25:17,630 Beatles songs, you can't tell this. 521 00:25:17,630 --> 00:25:19,480 In the song, you can really tell 522 00:25:19,480 --> 00:25:24,560 the accent from Liverpool. 523 00:25:24,560 --> 00:25:25,680 Listen carefully. 524 00:25:25,680 --> 00:25:27,240 You'll hear the pronunciation. 525 00:25:27,240 --> 00:25:29,040 That Merseyside accent. 526 00:25:29,040 --> 00:25:32,260 And the way they're playing is the old skiffle. 527 00:25:32,260 --> 00:25:33,890 This is how they started, in the clubs in 528 00:25:33,890 --> 00:25:34,720 Hamburg and so on. 529 00:25:34,720 --> 00:25:36,500 This is this is not advanced Beatles. 530 00:25:36,500 --> 00:25:39,360 They were playing here, it's sort of little joke in the 531 00:25:39,360 --> 00:25:40,660 middle of the Abbey Road album. 532 00:25:40,660 --> 00:25:43,500 They go retro and show the way they were when they first 533 00:25:43,500 --> 00:25:44,705 formed the band. 534 00:25:44,705 --> 00:25:47,680 [AUDIO CLIP REMOVED ] 535 00:25:47,680 --> 00:25:48,910 PROFESSOR: Did you catch that? 536 00:25:48,910 --> 00:25:51,290 The Liverpudlian accent? 537 00:25:51,290 --> 00:25:53,420 It comes complete with the glottal stop? 538 00:25:53,420 --> 00:25:55,670 [IMITATING ACCENT] 539 00:25:55,670 --> 00:25:58,390 You know how you eat the tea? 540 00:25:58,390 --> 00:26:00,010 Give me a bottle? 541 00:26:00,010 --> 00:26:00,530 Yeah. 542 00:26:00,530 --> 00:26:02,790 That's all from Liverpool. 543 00:26:02,790 --> 00:26:04,810 Merseyside. 544 00:26:04,810 --> 00:26:05,540 OK. 545 00:26:05,540 --> 00:26:07,600 So now what do I have here? 546 00:26:07,600 --> 00:26:11,110 Oh, here's recyclability codes. 547 00:26:11,110 --> 00:26:13,030 Throw this in, you know, it's a part of 548 00:26:13,030 --> 00:26:14,230 the part of the pack. 549 00:26:14,230 --> 00:26:17,200 So there's the polyethylene terephthalate, 550 00:26:17,200 --> 00:26:17,970 that I've shown you. 551 00:26:17,970 --> 00:26:23,750 This is high-density polyethylene, PVC, low-density 552 00:26:23,750 --> 00:26:24,850 polyethylene, and so on. 553 00:26:24,850 --> 00:26:25,900 And look here. 554 00:26:25,900 --> 00:26:30,770 Invented by, invented by, invented by, invented by. 555 00:26:30,770 --> 00:26:32,820 These are all man-made materials. 556 00:26:32,820 --> 00:26:38,460 They didn't exist before. 557 00:26:38,460 --> 00:26:39,580 Keep going. 558 00:26:39,580 --> 00:26:42,570 Invented by, invented by. 559 00:26:42,570 --> 00:26:43,930 And they're all invented in the 20th 560 00:26:43,930 --> 00:26:45,720 century, with one exception. 561 00:26:45,720 --> 00:26:49,740 A pharmacist in Germany by the name of Eduard Simon was 562 00:26:49,740 --> 00:26:57,380 playing with the vinyl benzene and managed to make this goo 563 00:26:57,380 --> 00:27:01,500 that became what we know as polystyrene. 564 00:27:01,500 --> 00:27:03,530 And nobody could explain. 565 00:27:03,530 --> 00:27:05,270 Remember, in 18-- 566 00:27:05,270 --> 00:27:09,390 he was doing this in 1839, before Kekule had even 567 00:27:09,390 --> 00:27:13,120 speculated that you can get carbon-carbon linkages! 568 00:27:13,120 --> 00:27:15,050 No benzene rings! 569 00:27:15,050 --> 00:27:17,840 So that he was linking benzene, that they didn't even 570 00:27:17,840 --> 00:27:20,630 understand existed as a ring, and he was making polymers 571 00:27:20,630 --> 00:27:22,610 that they didn't appreciate that you could even make 572 00:27:22,610 --> 00:27:29,780 C17H36, let alone C10,017. 573 00:27:29,780 --> 00:27:34,010 So in 1922, Hermann Staudinger gave the explanation that what 574 00:27:34,010 --> 00:27:36,570 we're seeing here is the polymerization into 575 00:27:36,570 --> 00:27:37,550 macromolecules. 576 00:27:37,550 --> 00:27:40,230 And for that, he got the Nobel Prize in 1953. 577 00:27:40,230 --> 00:27:43,270 Note, it took 30 years. 578 00:27:43,270 --> 00:27:45,750 You don't invent something that's really, really 579 00:27:45,750 --> 00:27:48,520 prize-winning, and on the way home, turn on the radio and 580 00:27:48,520 --> 00:27:51,340 discover, oh, I won the Nobel Prize. 581 00:27:51,340 --> 00:27:52,770 It takes time. 582 00:27:52,770 --> 00:27:55,260 And especially, the more remarkable the discovery, it 583 00:27:55,260 --> 00:27:57,460 takes time before people accept it and say, 584 00:27:57,460 --> 00:27:58,520 this is not a hoax. 585 00:27:58,520 --> 00:27:58,980 This is real. 586 00:27:58,980 --> 00:28:00,550 They didn't have the characterization. 587 00:28:00,550 --> 00:28:03,870 How were they going to verify in 1922? 588 00:28:03,870 --> 00:28:05,000 So you keep waiting, waiting, waiting. 589 00:28:05,000 --> 00:28:05,740 Look at what happened to de Broglie. 590 00:28:05,740 --> 00:28:08,470 De Broglie said, lambda equals h over p, 591 00:28:08,470 --> 00:28:09,720 and they went, uh-huh. 592 00:28:09,720 --> 00:28:11,820 And then, as soon as the fellows did the experiment 593 00:28:11,820 --> 00:28:14,040 down at Bell Labs and they got electron defraction-- 594 00:28:14,040 --> 00:28:14,460 boom! 595 00:28:14,460 --> 00:28:15,600 He gets the Nobel Prize. 596 00:28:15,600 --> 00:28:16,110 They said, you know what? 597 00:28:16,110 --> 00:28:18,020 You're right! 598 00:28:18,020 --> 00:28:19,270 That's how it works. 599 00:28:21,560 --> 00:28:21,930 OK. 600 00:28:21,930 --> 00:28:23,070 This was one of the giants. 601 00:28:23,070 --> 00:28:24,460 This was Wallace Carothers. 602 00:28:24,460 --> 00:28:26,930 Carothers, who for a short time was 603 00:28:26,930 --> 00:28:28,350 a lecturer at Harvard. 604 00:28:28,350 --> 00:28:33,320 He left Harvard and joined DuPont, and he gave birth to 605 00:28:33,320 --> 00:28:38,980 an incredible array of synthetic materials, as they 606 00:28:38,980 --> 00:28:40,730 say here, similar to cellulose and silicon. 607 00:28:40,730 --> 00:28:42,890 Invented neoprene, the first synthetic rubber. 608 00:28:42,890 --> 00:28:45,340 This was very important for the United States and the 609 00:28:45,340 --> 00:28:48,710 Allied Powers during World War II, because we did not have 610 00:28:48,710 --> 00:28:51,740 access to natural rubber. 611 00:28:51,740 --> 00:28:55,380 And the fact that they were making synthetic rubber here 612 00:28:55,380 --> 00:28:59,120 from materials that we had here allowed us to continue 613 00:28:59,120 --> 00:29:01,030 building for the war effort. 614 00:29:01,030 --> 00:29:06,760 Invented nylon, in 1937. 615 00:29:06,760 --> 00:29:07,660 An amazing man. 616 00:29:07,660 --> 00:29:12,420 Unfortunately deeply troubled, very depressive. 617 00:29:12,420 --> 00:29:17,110 And two days after his 41st birthday, he checked in a 618 00:29:17,110 --> 00:29:20,690 hotel in Philadelphia, and took his own life. 619 00:29:20,690 --> 00:29:21,940 This is Wallace Carothers. 620 00:29:24,460 --> 00:29:26,990 So I'm going to show you now some synthesis. 621 00:29:26,990 --> 00:29:29,610 About ten years ago, I had a live demonstration here. 622 00:29:29,610 --> 00:29:31,880 There was a gal who was doing her PhD over here in Building 623 00:29:31,880 --> 00:29:34,070 13, and she'd come in and do these demos. 624 00:29:34,070 --> 00:29:36,760 But, you know, it's been ten years now. 625 00:29:36,760 --> 00:29:39,610 We let her graduate, so she's not around anymore. 626 00:29:39,610 --> 00:29:40,970 So we took some videos of it. 627 00:29:40,970 --> 00:29:42,270 So the first thing I want to show you is the 628 00:29:42,270 --> 00:29:44,070 synthesis of nylon. 629 00:29:44,070 --> 00:29:45,920 So you're going to see this reaction. 630 00:29:45,920 --> 00:29:49,130 So in this case, it's hexamethylene diamine and 631 00:29:49,130 --> 00:29:50,160 adipic acid. 632 00:29:50,160 --> 00:29:53,540 And that's going to give you nylon-6,6 plus water, just as 633 00:29:53,540 --> 00:29:57,200 this reaction indicates here, and these are immiscible. 634 00:29:57,200 --> 00:30:00,030 See, the adipic acid is in aqueous phase, and the 635 00:30:00,030 --> 00:30:02,920 hexamethylene diamine is a non-aqueous phase, so they 636 00:30:02,920 --> 00:30:06,400 form two phases right here, two liquid layers, and this 637 00:30:06,400 --> 00:30:08,230 reaction occurs at the interface 638 00:30:08,230 --> 00:30:09,630 between the two layers. 639 00:30:09,630 --> 00:30:12,530 So you're going to see a close up of the beaker, and she's 640 00:30:12,530 --> 00:30:15,200 going to now dip an instrument in, and 641 00:30:15,200 --> 00:30:16,710 start pulling the solid. 642 00:30:16,710 --> 00:30:19,085 She's making the solid from two liquids, and she's going 643 00:30:19,085 --> 00:30:19,710 to pull it. 644 00:30:19,710 --> 00:30:23,270 And as she pulls it, she clears the interface. 645 00:30:23,270 --> 00:30:27,020 Because once the interface is covered, new 646 00:30:27,020 --> 00:30:28,380 reactant can't get there. 647 00:30:28,380 --> 00:30:31,980 So ironically, the product separates the two halves of 648 00:30:31,980 --> 00:30:33,850 the reaction from each other. 649 00:30:33,850 --> 00:30:36,350 So you have to get the product out. 650 00:30:36,350 --> 00:30:37,100 This is really cool. 651 00:30:37,100 --> 00:30:38,550 So there's the chemistry. 652 00:30:38,550 --> 00:30:39,140 So let's look. 653 00:30:39,140 --> 00:30:40,170 This is Heidi Burch. 654 00:30:40,170 --> 00:30:42,190 David, could we dim the lights, maybe? 655 00:30:42,190 --> 00:30:42,653 [FILM PLAYBACK] 656 00:30:42,653 --> 00:30:45,980 HEIDI BURCH: The derivative of a carboxylic acid then is 657 00:30:45,980 --> 00:30:46,976 mercuric chloride. 658 00:30:46,976 --> 00:30:49,964 I have it dissolved in hexane. 659 00:30:49,964 --> 00:30:53,079 My base is hexamethylene diamine, and I've got it 660 00:30:53,079 --> 00:30:53,460 dissolved in water. 661 00:30:53,460 --> 00:30:57,250 So to do this right, I have to make them float. 662 00:30:57,250 --> 00:31:03,620 So we're going to pour, if I can get it open. 663 00:31:03,620 --> 00:31:05,220 PROFESSOR: This is the old 10-250, too. 664 00:31:05,220 --> 00:31:06,240 It's got a carpet here. 665 00:31:06,240 --> 00:31:08,475 HEIDI BURCH: --because it's dissolved in water, which has 666 00:31:08,475 --> 00:31:11,485 a higher density than hexane. 667 00:31:16,160 --> 00:31:18,370 And then I have my acid dissolved in the hexane. 668 00:31:18,370 --> 00:31:20,440 So what's going to happen when I pour that in? 669 00:31:20,440 --> 00:31:21,973 It's not going to mix, right? 670 00:31:25,080 --> 00:31:25,490 PROFESSOR: It'll separate. 671 00:31:25,490 --> 00:31:27,160 HEIDI BURCH: It's going to phase separate, exactly. 672 00:31:27,160 --> 00:31:28,680 And we're going to have strata. 673 00:31:28,680 --> 00:31:30,245 Is that going to help or hurt our reaction? 674 00:31:34,230 --> 00:31:36,420 It's going to hurt our reaction, right? 675 00:31:36,420 --> 00:31:39,560 To have a good reaction, you need intimate mixing. 676 00:31:39,560 --> 00:31:42,010 Well-- 677 00:31:42,010 --> 00:31:43,760 PROFESSOR: This is like the Uzo water problem. 678 00:31:46,370 --> 00:31:48,080 HEIDI BURCH: So this is pretty, actually pretty 679 00:31:48,080 --> 00:31:48,980 unexciting. 680 00:31:48,980 --> 00:31:50,525 Nothing really interesting has happened. 681 00:31:50,525 --> 00:31:51,420 It's just kind of sitting there. 682 00:31:51,420 --> 00:31:54,580 Nothing's exploding out of the beaker, nothing's coming out. 683 00:31:54,580 --> 00:31:56,660 It's kind of tame. 684 00:31:56,660 --> 00:32:01,150 But if you look carefully, you can kind of see-- 685 00:32:01,150 --> 00:32:03,572 where did my pointer go? 686 00:32:03,572 --> 00:32:05,965 You can kind of see this film right there. 687 00:32:05,965 --> 00:32:07,740 See that big bubble? 688 00:32:07,740 --> 00:32:11,400 Well, there's a scum that's floating at the interface 689 00:32:11,400 --> 00:32:12,260 between the two layers. 690 00:32:12,260 --> 00:32:15,230 That's actually the nylon that we formed. 691 00:32:15,230 --> 00:32:18,430 What happens is, I mentioned that nylon has that excellent 692 00:32:18,430 --> 00:32:20,150 chemical resistance. 693 00:32:20,150 --> 00:32:24,225 Well, when we formed it, it made a barrier film between 694 00:32:24,225 --> 00:32:28,110 the two layers so that no more reactants could get through to 695 00:32:28,110 --> 00:32:31,590 each other to form more nylons. 696 00:32:31,590 --> 00:32:35,980 So what I have to do is remove that barrier film to allow the 697 00:32:35,980 --> 00:32:37,675 reactants to come into contact. 698 00:32:37,675 --> 00:32:42,690 And I'm doing that by drawing off the nylon as it's formed. 699 00:32:42,690 --> 00:32:45,650 Because I'm drawing off the film, are very haphazard. 700 00:32:45,650 --> 00:32:49,120 And what's happening is, the polymer I'm forming has a very 701 00:32:49,120 --> 00:32:50,990 broad molecular weight distribution. 702 00:32:50,990 --> 00:32:55,366 It's not all 240 grams per mole or whatever. 703 00:32:55,366 --> 00:32:58,256 And that greatly affects the mechanical properties, and, in 704 00:32:58,256 --> 00:33:00,620 fact, it affects them detrimentally. 705 00:33:00,620 --> 00:33:03,110 So the mechanical properties of this nylon that I'm forming 706 00:33:03,110 --> 00:33:05,030 aren't very good. 707 00:33:05,030 --> 00:33:05,450 [END FILM PLAYBACK] 708 00:33:05,450 --> 00:33:05,660 PROFESSOR: OK. 709 00:33:05,660 --> 00:33:08,960 So that's the first one. 710 00:33:08,960 --> 00:33:13,450 Now, the second one I'm going to show you talks about glass 711 00:33:13,450 --> 00:33:16,290 transition temperature, and how you engineer a rubber. 712 00:33:16,290 --> 00:33:20,360 So it might shock you to know that a rubber 713 00:33:20,360 --> 00:33:21,980 is, in fact, a liquid. 714 00:33:21,980 --> 00:33:25,150 It's a polymer that's above its glass transition 715 00:33:25,150 --> 00:33:25,720 temperature. 716 00:33:25,720 --> 00:33:28,260 It might be supercooled liquid, but it's liquid. 717 00:33:28,260 --> 00:33:32,150 And those disulfide linkages give you the flexibility so 718 00:33:32,150 --> 00:33:34,860 that the chains can move against one another. 719 00:33:34,860 --> 00:33:37,590 If you drop the temperature below the glass transition 720 00:33:37,590 --> 00:33:41,860 temperature, the whole thing turns into an amorphous solid. 721 00:33:41,860 --> 00:33:43,790 So what are the mechanical properties? 722 00:33:43,790 --> 00:33:46,200 What I'm indicating here is the ball, all right? 723 00:33:46,200 --> 00:33:50,420 So the bouncing ball is up here, above the glass 724 00:33:50,420 --> 00:33:52,460 transition temperature it's cross-linked and 725 00:33:52,460 --> 00:33:54,740 behaves as an elastomer. 726 00:33:54,740 --> 00:33:58,590 If you get the temperature too low, you'll end up solidifying 727 00:33:58,590 --> 00:34:00,710 everything, and then it turns into something with the 728 00:34:00,710 --> 00:34:03,640 mechanical properties of a billiard ball, all right? 729 00:34:03,640 --> 00:34:04,790 So we call that tough. 730 00:34:04,790 --> 00:34:06,830 Tough means it has impact resistance. 731 00:34:06,830 --> 00:34:08,250 It will absorb a lot of energy. 732 00:34:08,250 --> 00:34:10,960 So if I drop the ball, it won't bounce, it takes the 733 00:34:10,960 --> 00:34:14,200 energy of falling and absorbs it and holds it. 734 00:34:14,200 --> 00:34:15,560 So if you want a ball to bounce, you 735 00:34:15,560 --> 00:34:16,610 want to be above here. 736 00:34:16,610 --> 00:34:18,090 So what we're going to do, is we're going to take two 737 00:34:18,090 --> 00:34:19,220 different polymers. 738 00:34:19,220 --> 00:34:23,070 One that at room temperature is here, and one that at room 739 00:34:23,070 --> 00:34:24,550 temperature is here. 740 00:34:24,550 --> 00:34:26,400 The one that's down here, we're going to put in the 741 00:34:26,400 --> 00:34:28,540 boiling water and get it over here. 742 00:34:28,540 --> 00:34:31,690 The one that is naturally a bouncer here, we're going to 743 00:34:31,690 --> 00:34:34,210 put into liquid nitrogen and send it over here. 744 00:34:34,210 --> 00:34:36,770 So we're going to make a bouncing ball not bounce, and 745 00:34:36,770 --> 00:34:40,710 we're going to make a flat unbouncy ball bounce. 746 00:34:40,710 --> 00:34:42,044 We're going to teach these balls. 747 00:34:42,044 --> 00:34:43,010 And what are we going to do? 748 00:34:43,010 --> 00:34:45,050 We're going to teach these balls how to bounce and not 749 00:34:45,050 --> 00:34:49,140 bounce on temperature cue, by moving on opposite sides of 750 00:34:49,140 --> 00:34:50,590 the glass transition temperature. 751 00:34:50,590 --> 00:34:55,440 So this is a glass, and this over here is a rubber, OK? 752 00:34:55,440 --> 00:34:55,770 All right. 753 00:34:55,770 --> 00:34:56,340 So here they are. 754 00:34:56,340 --> 00:34:58,060 Those are the two rubbers. 755 00:34:58,060 --> 00:35:00,270 One is norbornene, and the other is isoprene. 756 00:35:00,270 --> 00:35:02,990 And both of these, if you go back to the earlier slides, 757 00:35:02,990 --> 00:35:06,410 have a double bond in the polymer, And that double bond 758 00:35:06,410 --> 00:35:09,450 has now been broken for disulfide linkages. 759 00:35:09,450 --> 00:35:10,620 This is Heidi again. 760 00:35:10,620 --> 00:35:11,070 [FILM PLAYBACK] 761 00:35:11,070 --> 00:35:11,202 HEIDI BURCH: OK. 762 00:35:11,202 --> 00:35:13,630 The thing I want to talk about now, is the effect of 763 00:35:13,630 --> 00:35:17,150 temperature on polymer molecules. 764 00:35:17,150 --> 00:35:19,880 Basically, when do I get rubbery behavior and when do I 765 00:35:19,880 --> 00:35:21,340 get glassy behavior? 766 00:35:21,340 --> 00:35:23,960 Because I can get the same polymer to exhibit rubbery 767 00:35:23,960 --> 00:35:26,895 behavior or glassy behavior, depending on the temperature 768 00:35:26,895 --> 00:35:28,780 at which I use that material. 769 00:35:28,780 --> 00:35:31,480 As Dr. Sadoway told you, polymers have what's called a 770 00:35:31,480 --> 00:35:34,220 glass transition temperature, and the type of behavior that 771 00:35:34,220 --> 00:35:38,570 I get is determined by my use temperature relative to my 772 00:35:38,570 --> 00:35:40,780 glass transition temperature. 773 00:35:40,780 --> 00:35:48,410 So I have here six little balls with 774 00:35:48,410 --> 00:35:50,040 faces painted on them. 775 00:35:50,040 --> 00:35:54,430 The ones with the happy faces are polyisoprene. 776 00:35:54,430 --> 00:35:58,560 The ones with the sad faces are polynorbornene. 777 00:35:58,560 --> 00:36:01,010 Now, polynorbornene is a synthetic rubber that was 778 00:36:01,010 --> 00:36:03,630 developed during World War II when we didn't have access to 779 00:36:03,630 --> 00:36:07,545 all the rubber tree groves in Southeast Asia. 780 00:36:07,545 --> 00:36:10,195 So the happy balls are happy because their glass transition 781 00:36:10,195 --> 00:36:12,450 temperature is minus 67. 782 00:36:12,450 --> 00:36:15,770 So our use temperature at room temperature is much greater 783 00:36:15,770 --> 00:36:18,230 that their glass transition temperatures, so they behave 784 00:36:18,230 --> 00:36:20,390 as rubber would. 785 00:36:20,390 --> 00:36:25,730 The polynorbornene has a glass transition temperature of 40. 786 00:36:25,730 --> 00:36:28,220 So we're actually below its glass transition temperature 787 00:36:28,220 --> 00:36:30,462 at room temperature, and it just 788 00:36:30,462 --> 00:36:31,770 dissipates all the energy. 789 00:36:31,770 --> 00:36:35,380 We get a much more glassy-like behavior from this material, 790 00:36:35,380 --> 00:36:36,740 and it doesn't bounce. 791 00:36:36,740 --> 00:36:40,520 So what we can do here to demonstrate the effect is 792 00:36:40,520 --> 00:36:45,125 we're going raise the use temperature of both materials, 793 00:36:45,125 --> 00:36:46,410 and we're going to lower the use 794 00:36:46,410 --> 00:36:48,200 temperature of both materials. 795 00:36:48,200 --> 00:36:50,290 So I'm going to drop them in boiling water, and hope that 796 00:36:50,290 --> 00:36:52,215 the little faces stay on, because I just painted them on 797 00:36:52,215 --> 00:36:53,890 with white-out. 798 00:36:53,890 --> 00:36:55,170 I don't know how that's going to work. 799 00:36:55,170 --> 00:36:58,450 And then I'm going to drop two of them in liquid nitrogen. 800 00:36:58,450 --> 00:37:00,020 Now, these will be our controls. 801 00:37:00,020 --> 00:37:03,950 Remember, polynorbornene, polyisoprene. 802 00:37:03,950 --> 00:37:06,755 Now something to think about, which I know Dr. Sadoway 803 00:37:06,755 --> 00:37:10,230 always likes to ask, is why does one have a high glass 804 00:37:10,230 --> 00:37:12,460 transition temperature, and why does one have a low glass 805 00:37:12,460 --> 00:37:13,720 transition temperature? 806 00:37:13,720 --> 00:37:17,220 And I'll leave you to ponder that little conundrum, while I 807 00:37:17,220 --> 00:37:18,530 try to fish these bad boys out. 808 00:37:22,830 --> 00:37:23,320 OK. 809 00:37:23,320 --> 00:37:23,810 Oh! 810 00:37:23,810 --> 00:37:24,856 White-out worked. 811 00:37:24,856 --> 00:37:27,810 So this is the polyisoprene. 812 00:37:27,810 --> 00:37:29,060 Can you hear the sound that it makes? 813 00:37:32,800 --> 00:37:35,610 When I drop the one that's at room temperature, I get a nice 814 00:37:35,610 --> 00:37:36,860 rubbery sound. 815 00:37:39,970 --> 00:37:43,850 When I drop that one, I get a plastic, hard glassy sound. 816 00:37:43,850 --> 00:37:47,640 I've cooled it below its glass transition temperature, and 817 00:37:47,640 --> 00:37:50,670 now I get a totally glassy impact, like if I were 818 00:37:50,670 --> 00:37:52,920 knocking pool balls together. 819 00:37:52,920 --> 00:37:57,440 Now let's go in for the polynorbornene. 820 00:37:57,440 --> 00:37:57,630 Oh! 821 00:37:57,630 --> 00:38:00,730 His eye came off. 822 00:38:00,730 --> 00:38:01,640 Same thing. 823 00:38:01,640 --> 00:38:04,090 I pulled the polynorbornene below its glass transition 824 00:38:04,090 --> 00:38:07,030 temperature as well, so it, too, exhibits a glassy 825 00:38:07,030 --> 00:38:10,230 collision, like a pool ball. 826 00:38:10,230 --> 00:38:14,338 Now, let's go in here. 827 00:38:14,338 --> 00:38:17,495 This is the polynorbornene, so it should still continue to 828 00:38:17,495 --> 00:38:21,920 bounce, because we've raised its use temperature further 829 00:38:21,920 --> 00:38:24,160 above its glass transition temperature. 830 00:38:24,160 --> 00:38:25,690 That's not the exciting one. 831 00:38:25,690 --> 00:38:28,276 The exciting one is-- 832 00:38:28,276 --> 00:38:31,050 if I can get it out. 833 00:38:31,050 --> 00:38:35,000 What happens to the polynorbornene? 834 00:38:35,000 --> 00:38:37,310 This is the sad ball, the one that wouldn't bounce at room 835 00:38:37,310 --> 00:38:38,440 temperature. 836 00:38:38,440 --> 00:38:41,625 By raising its use temperature above its glass transition 837 00:38:41,625 --> 00:38:43,900 temperature by dunking it in boiling water, I 838 00:38:43,900 --> 00:38:45,430 get a rubbery response. 839 00:38:45,430 --> 00:38:47,630 [END FILM PLAYBACK] 840 00:38:47,630 --> 00:38:48,750 PROFESSOR: Super. 841 00:38:48,750 --> 00:38:49,000 OK. 842 00:38:49,000 --> 00:38:52,270 House lights, please. 843 00:38:52,270 --> 00:38:53,760 I don't read well in the dark. 844 00:38:53,760 --> 00:38:54,430 OK. 845 00:38:54,430 --> 00:39:02,750 So I hope you've seen some examples of how these work. 846 00:39:02,750 --> 00:39:04,830 So now I want to talk a little bit about the 847 00:39:04,830 --> 00:39:05,900 broader societal issues. 848 00:39:05,900 --> 00:39:07,820 So this, I think, is sort of a pattern of 849 00:39:07,820 --> 00:39:09,770 adoption of new materials. 850 00:39:09,770 --> 00:39:12,620 You start off with this wonder, you know, this cool 851 00:39:12,620 --> 00:39:14,840 property that you get at the lab bench. 852 00:39:14,840 --> 00:39:19,020 You know, when nylon was invented, it led to 853 00:39:19,020 --> 00:39:19,912 democratization. 854 00:39:19,912 --> 00:39:24,430 Do you realize stockings, womens' stockings, were only 855 00:39:24,430 --> 00:39:25,730 owned by the wealthy? 856 00:39:25,730 --> 00:39:26,850 Because they were made of silk. 857 00:39:26,850 --> 00:39:29,550 When they were made out of nylon, they 858 00:39:29,550 --> 00:39:31,590 became cheap and abundant. 859 00:39:31,590 --> 00:39:33,750 So that changed the way people dressed. 860 00:39:33,750 --> 00:39:38,990 It changed the way people made clothing in a way that was 861 00:39:38,990 --> 00:39:41,180 unimaginable before. 862 00:39:41,180 --> 00:39:45,790 So you could, for example, make a billiard ball, or piano 863 00:39:45,790 --> 00:39:47,910 keys, without killing an elephant. 864 00:39:47,910 --> 00:39:49,980 You didn't have to use ivory. 865 00:39:49,980 --> 00:39:52,170 You could use polymers. 866 00:39:52,170 --> 00:39:55,970 Huge, huge implications. 867 00:39:55,970 --> 00:39:59,150 So this is one of the first commercial polymers. 868 00:39:59,150 --> 00:40:03,050 It's phenolic resin, and it's made by a condensation 869 00:40:03,050 --> 00:40:05,070 polymerization between carbolic acid and 870 00:40:05,070 --> 00:40:05,510 formaldehyde. 871 00:40:05,510 --> 00:40:06,960 It was called bakelite. 872 00:40:06,960 --> 00:40:10,120 and its corporate symbol was B with the infinity sign. 873 00:40:10,120 --> 00:40:11,700 Material of a thousand uses. 874 00:40:11,700 --> 00:40:13,000 And this, normally, is-- 875 00:40:13,000 --> 00:40:15,290 look at the elaborate art deco coffeepot. 876 00:40:15,290 --> 00:40:18,620 And this is all-- it's thermal insulated, and so on. 877 00:40:18,620 --> 00:40:22,000 These are all plumbing parts made out of bakelite, that 878 00:40:22,000 --> 00:40:24,400 previously would be made out of many pieces of metal that 879 00:40:24,400 --> 00:40:26,320 had to be machined and fashioned together. 880 00:40:26,320 --> 00:40:29,780 You could take bakelite powder, put it into a die, 881 00:40:29,780 --> 00:40:34,240 heat it, and out comes the part, finished, in one step. 882 00:40:34,240 --> 00:40:38,420 So this has a huge implication on productivity. 883 00:40:38,420 --> 00:40:42,010 But then, so now we start talking about substitution, 884 00:40:42,010 --> 00:40:45,300 making the cheap things, the piano keys, the fork here, and 885 00:40:45,300 --> 00:40:46,310 on and on and on. 886 00:40:46,310 --> 00:40:48,850 But then things that couldn't exist before. 887 00:40:48,850 --> 00:40:52,440 You know, the movie film. 888 00:40:52,440 --> 00:40:53,580 Look at the steering wheel here. 889 00:40:53,580 --> 00:40:55,350 There's the, that's indicating the lady's 890 00:40:55,350 --> 00:40:58,390 stocking, and so on. 891 00:40:58,390 --> 00:41:01,120 This is from Look magazine, 1940. 892 00:41:01,120 --> 00:41:04,270 People thought these things were just godsends. 893 00:41:04,270 --> 00:41:06,130 This is Synthetica. 894 00:41:06,130 --> 00:41:08,470 This is a country, and it's got the province of Cellulose, 895 00:41:08,470 --> 00:41:13,600 Petrolia, Castphenolic and so on. 896 00:41:13,600 --> 00:41:15,430 This is the 1960s. 897 00:41:15,430 --> 00:41:17,740 This is plastics, the future has arrived. 898 00:41:17,740 --> 00:41:19,820 It's at a museum in New York. 899 00:41:19,820 --> 00:41:23,350 You're looking at the interior of a home with furniture built 900 00:41:23,350 --> 00:41:28,160 in, and it's all plastic walls, and formed, and so on. 901 00:41:28,160 --> 00:41:30,110 I think maybe these guys were in a drug haze or something. 902 00:41:30,110 --> 00:41:31,190 Those are the windows. 903 00:41:31,190 --> 00:41:33,230 Maybe they thought those windows were square, 904 00:41:33,230 --> 00:41:35,140 rectilinear, I don't know. 905 00:41:35,140 --> 00:41:38,480 So this is going way overboard. 906 00:41:38,480 --> 00:41:41,320 And then let me show you a piece of iconic 907 00:41:41,320 --> 00:41:42,490 film from The Graduate. 908 00:41:42,490 --> 00:41:44,220 You'll see a young Dustin Hoffman. 909 00:41:44,220 --> 00:41:46,890 He's just come back from getting a bachelor's degree. 910 00:41:46,890 --> 00:41:50,030 So this could be you someday in the not too distant future. 911 00:41:50,030 --> 00:41:52,350 And he's at a party that his parents are 912 00:41:52,350 --> 00:41:54,404 throwing in his honor. 913 00:41:54,404 --> 00:41:54,891 [FILM PLAYBACK] 914 00:41:54,891 --> 00:41:56,352 -We're all so proud of you! 915 00:41:56,352 --> 00:42:00,531 Proud, proud, proud, proud, proud, proud. 916 00:42:00,531 --> 00:42:02,004 What are you going to do now? 917 00:42:02,004 --> 00:42:04,459 -I was going to go upstairs for a minute. 918 00:42:04,459 --> 00:42:05,812 -I mean with your future? 919 00:42:05,812 --> 00:42:07,105 Your life? 920 00:42:07,105 --> 00:42:08,896 'Well, that's a little hard to say. 921 00:42:08,896 --> 00:42:09,800 -Ben. 922 00:42:09,800 --> 00:42:11,440 -Excuse me. 923 00:42:11,440 --> 00:42:13,880 -Mr. McGuire? 924 00:42:13,880 --> 00:42:15,734 -Ben. 925 00:42:15,734 --> 00:42:17,198 -Mr. McGuire. 926 00:42:17,198 --> 00:42:18,180 -Come with me for a minute. 927 00:42:18,180 --> 00:42:18,880 PROFESSOR: See the lipstick? 928 00:42:18,880 --> 00:42:20,396 -I want to talk to you. 929 00:42:20,396 --> 00:42:22,680 Excuse us, Joanne. 930 00:42:22,680 --> 00:42:24,280 PROFESSOR: See, it's the '60s. 931 00:42:24,280 --> 00:42:25,390 They blow off the ladies. 932 00:42:25,390 --> 00:42:26,640 Now the men are going to talk. 933 00:42:32,775 --> 00:42:35,260 -I just want to say one word to you. 934 00:42:35,260 --> 00:42:38,655 Just one word. 935 00:42:38,655 --> 00:42:40,110 -Yes, sir? 936 00:42:40,110 --> 00:42:40,595 -Are you listening? 937 00:42:40,595 --> 00:42:42,550 -Yes, I am. 938 00:42:42,550 --> 00:42:43,800 -Plastics. 939 00:42:47,030 --> 00:42:49,010 -Exactly how do you mean? 940 00:42:49,010 --> 00:42:51,440 -There's a great future in plastics. 941 00:42:51,440 --> 00:42:52,890 Think about it. 942 00:42:52,890 --> 00:42:53,580 Will you think about it? 943 00:42:53,580 --> 00:42:54,350 -Yes, I will. 944 00:42:54,350 --> 00:42:55,850 -Enough said. 945 00:42:55,850 --> 00:42:58,850 That's a deal. 946 00:42:58,850 --> 00:42:59,350 [END FILM PLAYBACK] 947 00:42:59,350 --> 00:42:59,530 PROFESSOR: All right. 948 00:42:59,530 --> 00:43:03,780 So this was 1967, '68. 949 00:43:03,780 --> 00:43:05,710 So what's happened since then in plastics? 950 00:43:05,710 --> 00:43:08,730 Well, all of these other considerations about 951 00:43:08,730 --> 00:43:13,790 recyclability, environmental health and safety issues. 952 00:43:13,790 --> 00:43:16,800 In order to facilitate molding, when you want to mold 953 00:43:16,800 --> 00:43:20,050 the plastic, to get those bonds to loosen up a little 954 00:43:20,050 --> 00:43:23,280 bit, we use a chemical known as a plasticizer. 955 00:43:23,280 --> 00:43:27,030 It's a low molecular weight polymer that helps the-- 956 00:43:27,030 --> 00:43:29,220 it's sort of the equivalent of putting a little bit of olive 957 00:43:29,220 --> 00:43:33,080 oil in with the pasta, to give it that freedom to move. 958 00:43:33,080 --> 00:43:35,910 And so this, then, when you sit in a new car, the new car 959 00:43:35,910 --> 00:43:38,670 smell is the smell of the plasticizer, which is still 960 00:43:38,670 --> 00:43:39,700 evaporating. 961 00:43:39,700 --> 00:43:42,950 And some of those plasticizers have molecular architectures 962 00:43:42,950 --> 00:43:45,590 that are similar to hormones in our bodies. 963 00:43:45,590 --> 00:43:49,890 And so it's not healthy for us to be breathing this stuff. 964 00:43:49,890 --> 00:43:53,390 So maybe the bright future that was talked about is not 965 00:43:53,390 --> 00:43:58,120 quite as bright as some people might have thought it to be. 966 00:43:58,120 --> 00:43:59,480 The other thing is-- 967 00:43:59,480 --> 00:44:01,670 you know how I showed you the plumbing parts? 968 00:44:01,670 --> 00:44:03,930 Well, we started making all kinds of 969 00:44:03,930 --> 00:44:07,150 things out of polymers. 970 00:44:07,150 --> 00:44:09,050 As a child, I remember my father bringing 971 00:44:09,050 --> 00:44:11,820 me, one day, a shoe. 972 00:44:11,820 --> 00:44:14,890 The shoe was 100% man-made. 973 00:44:14,890 --> 00:44:17,290 It was all polymer. 974 00:44:17,290 --> 00:44:20,930 And we thought this was the coolest thing, 975 00:44:20,930 --> 00:44:24,090 because of all man-made. 976 00:44:24,090 --> 00:44:26,200 Of course, there was a complete reversal. 977 00:44:26,200 --> 00:44:29,603 People said, you know, your foot can't breathe, and this 978 00:44:29,603 --> 00:44:32,280 is a silly thing to have. But at the time, we started 979 00:44:32,280 --> 00:44:35,590 making-- and they were ugly. 980 00:44:35,590 --> 00:44:37,730 And you know, for me, if it's ugly, I don't want to wear 981 00:44:37,730 --> 00:44:38,630 something that's ugly. 982 00:44:38,630 --> 00:44:42,680 So what happened was, we started making all kinds of 983 00:44:42,680 --> 00:44:44,790 things out of polymers, or as the public 984 00:44:44,790 --> 00:44:46,900 knows them, as plastics. 985 00:44:46,900 --> 00:44:52,110 And by the mid-'70s, to call something plastic was to make 986 00:44:52,110 --> 00:44:53,990 a derogatory comment. 987 00:44:53,990 --> 00:44:57,620 It's plastic, it's cheap, it's shoddy. 988 00:44:57,620 --> 00:45:01,350 So you know, making silk stockings cheaper as nylon 989 00:45:01,350 --> 00:45:02,530 stockings was good. 990 00:45:02,530 --> 00:45:05,200 But if you get them too cheap, they're cheap. 991 00:45:05,200 --> 00:45:05,750 See? 992 00:45:05,750 --> 00:45:07,030 So there's an optimum there. 993 00:45:07,030 --> 00:45:08,470 And all of that went into play. 994 00:45:08,470 --> 00:45:10,010 By the way, how do we get the word plastic? 995 00:45:10,010 --> 00:45:12,030 It comes from the Greek plastikos. 996 00:45:12,030 --> 00:45:14,060 And same word as potter. 997 00:45:14,060 --> 00:45:15,800 So when you're working with clay, you're working with a 998 00:45:15,800 --> 00:45:16,930 plastic medium. 999 00:45:16,930 --> 00:45:19,680 It's deformable, it's malleable. 1000 00:45:19,680 --> 00:45:24,240 There's Samuel Johnson "let Thy plastick hand." So all 1001 00:45:24,240 --> 00:45:28,180 plastics are polymers, but not all polymers are plastics, 1002 00:45:28,180 --> 00:45:30,980 because some polymers can't be deformed. 1003 00:45:30,980 --> 00:45:32,900 If they're below their glass transition temperature, 1004 00:45:32,900 --> 00:45:34,150 they're brittle solids. 1005 00:45:36,780 --> 00:45:37,150 All right. 1006 00:45:37,150 --> 00:45:40,440 So I've told you enough about concern. 1007 00:45:40,440 --> 00:45:42,170 Let's look at recycling. 1008 00:45:42,170 --> 00:45:45,420 In the United States right now, 100 billion pounds 1009 00:45:45,420 --> 00:45:48,500 annually of polymer, 50 million tons of which 3 to 4 1010 00:45:48,500 --> 00:45:50,110 million are recycled. 1011 00:45:50,110 --> 00:45:51,660 It's a very low recycle rate. 1012 00:45:51,660 --> 00:45:54,110 So this ends up in the waste. 1013 00:45:54,110 --> 00:45:55,950 Contrast that to steel. 1014 00:45:55,950 --> 00:45:59,250 Steel, we still make 80 million tons a year of virgin 1015 00:45:59,250 --> 00:46:01,110 metal in the United States. 1016 00:46:01,110 --> 00:46:03,300 It's still a world-class steel industry. 1017 00:46:03,300 --> 00:46:04,600 You can bet it's world-class. 1018 00:46:04,600 --> 00:46:08,050 With our wages and our high standards, if you're still in 1019 00:46:08,050 --> 00:46:10,130 business making steel in the United States, you 1020 00:46:10,130 --> 00:46:12,660 better be damn good. 1021 00:46:12,660 --> 00:46:13,900 Very good. 1022 00:46:13,900 --> 00:46:16,920 So 80 million tons virgin metal, 60 million tons 1023 00:46:16,920 --> 00:46:19,310 recycled scrap. 1024 00:46:19,310 --> 00:46:25,310 We recycle more steel per year from automobiles than we 1025 00:46:25,310 --> 00:46:27,830 consume building new automobiles. 1026 00:46:27,830 --> 00:46:29,080 It's a complete ecology. 1027 00:46:32,020 --> 00:46:33,900 And compare that to aluminum. 1028 00:46:33,900 --> 00:46:37,580 Aluminum, 4 million tons a year, 1 million tons recycled. 1029 00:46:37,580 --> 00:46:41,080 Very high rate on used beverage containers. 1030 00:46:41,080 --> 00:46:42,210 But that's the exception. 1031 00:46:42,210 --> 00:46:44,450 Because this was DFE, Designed For Environment. 1032 00:46:44,450 --> 00:46:48,570 The alloy choices were made in order to facilitate recycling. 1033 00:46:48,570 --> 00:46:51,280 So there were certain metals that were forbidden to go into 1034 00:46:51,280 --> 00:46:53,990 the alloy because they would pose 1035 00:46:53,990 --> 00:46:56,080 problems later in recycling. 1036 00:46:56,080 --> 00:46:58,960 So there are many ways to get the same deep-drawing 1037 00:46:58,960 --> 00:46:59,760 characteristics. 1038 00:46:59,760 --> 00:47:01,172 You know, you make a beverage can out of a 1039 00:47:01,172 --> 00:47:03,370 sheet, and you snap. 1040 00:47:03,370 --> 00:47:06,050 Punch down, punch up, there's no seam on the bottom. 1041 00:47:06,050 --> 00:47:08,630 This is made from a single sheet of metal. 1042 00:47:08,630 --> 00:47:11,330 And then a second piece comes down on the top. 1043 00:47:11,330 --> 00:47:14,100 And so this has only aluminum, silicon, and magnesium. 1044 00:47:14,100 --> 00:47:17,140 You could choose other metals, but with aluminum, silicon, 1045 00:47:17,140 --> 00:47:20,280 magnesium, it is recyclable. 1046 00:47:20,280 --> 00:47:22,720 But aluminum ladders-- if you're building an airplane, 1047 00:47:22,720 --> 00:47:25,495 let's say you're the chief purchasing agent for Boeing. 1048 00:47:25,495 --> 00:47:29,120 And you've got a choice of aluminum scrap, which, you 1049 00:47:29,120 --> 00:47:32,000 know, people might have thrown some old fishing weights with 1050 00:47:32,000 --> 00:47:36,390 lead in there, and that's now contaminant in the aluminum. 1051 00:47:36,390 --> 00:47:38,800 Or you're going to buy high-purity virgin metal, and 1052 00:47:38,800 --> 00:47:40,330 you're going to bet the company's future. 1053 00:47:40,330 --> 00:47:41,630 What are you going to buy? 1054 00:47:41,630 --> 00:47:45,050 You're going to put recycled metal into an airplane. 1055 00:47:45,050 --> 00:47:47,070 Have the thing fall out of the sky. 1056 00:47:47,070 --> 00:47:49,070 No way. 1057 00:47:49,070 --> 00:47:50,890 So you have to be careful. 1058 00:47:50,890 --> 00:47:54,890 Those alloys, if you take the, I told you, the door off the 1059 00:47:54,890 --> 00:47:59,280 1928 Model-T, and you put it on a 2010 Taurus, you can't 1060 00:47:59,280 --> 00:48:02,470 take the wing off a DC-3 and melt it down 1061 00:48:02,470 --> 00:48:04,670 and put it on a 777. 1062 00:48:04,670 --> 00:48:08,350 Because the top has an aluminum alloy with zinc, and 1063 00:48:08,350 --> 00:48:11,230 in the bottom one has an aluminum alloy with copper. 1064 00:48:11,230 --> 00:48:13,220 And if you co-melt those, you'll end up with 1065 00:48:13,220 --> 00:48:17,060 intermetallics, and the alloy is unusable. 1066 00:48:17,060 --> 00:48:18,960 So you have to separate them. 1067 00:48:18,960 --> 00:48:20,050 Now it's not so simple. 1068 00:48:20,050 --> 00:48:22,520 So before you go make pronouncements saying, yeah, 1069 00:48:22,520 --> 00:48:25,860 recycling is great, think about it. 1070 00:48:25,860 --> 00:48:28,530 Follow through. 1071 00:48:28,530 --> 00:48:29,070 OK. 1072 00:48:29,070 --> 00:48:32,990 If you find this interesting, and the impact that polymer 1073 00:48:32,990 --> 00:48:36,280 had on American culture, this is a lovely book by Jeffrey 1074 00:48:36,280 --> 00:48:40,510 Meikle on polymers and their use.