00:00:00 At this meeting there had been a lot of sessions on the history of various phases

00:00:29 of polymer chemistry, so I'm going to label this one my personal history of the area

00:00:38 of polymer chemistry from the beginning because I think I was the first man in the universities

00:00:45 that worked in polymers and that was more or less of an accident, but I got into it

00:00:50 and never got out.

00:00:53 Polymer chemistry in America started in the industry.

00:00:57 The industrial laboratories were making products out of horns and hoofs, grinding them up and

00:01:04 chewing them up with various chemicals and getting materials to make fancy combs for

00:01:10 women's hair and that was the principle start of plastic polymer chemistry.

00:01:18 Not exactly anybody knew what they were doing, the only thing they got was something useful

00:01:22 and of course that's worthwhile.

00:01:24 I really think that all of the major advances in the early days of polymer chemistry were

00:01:29 industrial and I'm not sure that isn't the reason that the university people still look

00:01:35 down their noses at polymer chemists thinking we're kind of second rate people and not really

00:01:42 good scientists.

00:01:43 I think that it's because the good work practically all started in industry and you know most

00:01:49 universities think that's kind of a dirty place to be.

00:01:55 One of the first developments after that was the cellulose chemistry.

00:02:00 Now they didn't know what cellulose was but they knew how to use it.

00:02:04 They made cellulose esters which they could disperse in various media and from that they

00:02:09 got cellulose xanthate for example which they could spin and pass into acid and get fibers

00:02:16 and that was one kind of cellulose rayon.

00:02:20 They also got clear films of cellulose which later called cellophane.

00:02:29 They made nitric acid esters of cellulose that they completely nitrated.

00:02:33 They had gun cotton.

00:02:34 It was partially nitrated and they called it pyroxylene and they mixed the pyroxylene

00:02:40 with camphor.

00:02:41 They got celluloid and that made slick collars and slick shirt fronts and slick cuffs for

00:02:48 the gentlemen for the evening wear but they had to be careful they dropped cigarette ash

00:02:53 on them and they had trouble because they were extremely inflammable.

00:02:59 Also they developed pyroxylene into films and the nitrocellulose films were the early

00:03:05 films for photography and there were several very serious accidents particularly in the

00:03:12 hospitals where the x-ray programs went forth.

00:03:15 They had big film stacks from the fire from the cellulose nitrate.

00:03:21 Then they developed the cellulose acetate films and they were safer.

00:03:25 Now all of this is not synthetic polymer chemistry.

00:03:29 This is using natural products.

00:03:32 They still didn't know what a polymer was and they just found out how to make these

00:03:36 products by pure technology.

00:03:40 The first synthetic polymer chemistry was due to Bakelund who brought over his process

00:03:48 for phenol formaldehyde which he developed first in Belgium.

00:03:55 They brought it to this country and marketed it in 1914 as Bakelite and that's still a

00:04:00 very important natural product, I don't mean a synthetic product, for electrical insulation,

00:04:08 cabinets of some kind, sometimes used as if you don't polymerize it too much you can use

00:04:14 it as a varnish and it's one of the first plastics, synthetics that was made and it's

00:04:22 one that is still very useful in general use.

00:04:26 Then after Bakelite came the development of urea formaldehyde resins and these were

00:04:33 colorless and could be made into decorative materials of one sort or another and that

00:04:38 was a particularly useful thing.

00:04:41 People liked to make fancy containers for various items that you put on the shelf to

00:04:47 look at.

00:04:50 They knew that formaldehyde and urea reacted to give methyl urea but they didn't know what

00:04:55 the rest of the process was.

00:04:56 It didn't matter, they got the product and could sell it.

00:05:01 Now about the third complex polymer that came out was from General Electric and Ameren Cyanamide

00:05:08 and they condensed phthalic anhydride in glycerol and got the glyptals.

00:05:14 Now the glyptals were very intractable if they cooked them too long but under the right

00:05:20 conditions which they found by experiment, they could get a glyptal which they could

00:05:25 use for making a varnish or paint vehicle and if they put a little more monobasic acid

00:05:34 in to balance the carboxyl to the phthalic anhydride with the hydroxyl and glycerol,

00:05:40 they could even get to a little bit of solubility and get paints and varnishes.

00:05:45 That was a very useful thing.

00:05:48 All of this was done now without understanding what a polymer was.

00:05:53 Polymers were some kind of mystic material, high molecular weight, they were pretty sure

00:05:58 of that and they were held together by some kind of mystic forces, not ordinary valence

00:06:04 forces and nobody really knew what they were.

00:06:09 Another one in that early bunch was the thiocals made from aliphatic polished sulfides, semi-rubbery

00:06:16 plastics and those were very important in the early days for making caulking materials

00:06:23 for flight decks and airplane carriers and now they almost died off, weren't any good.

00:06:30 Then suddenly found out they were the best binders there are for our explosives that

00:06:38 we used to carry the new sky orbiting vessels into orbit.

00:06:47 You blend high explosive with bakelite or with thioco, squeeze it into the container

00:06:55 and that's what carries your men around the moon.

00:06:59 But it's now again, after all these years, come back to be a very important plastic.

00:07:05 These were all made without knowing what a polymer was or what the general process was

00:07:11 and polymeric materials were still very much a matter of mystic.

00:07:18 Stauding about 1920 came out with the idea that they were macromolecules.

00:07:25 I don't know if any of you ever tried to read any of Staudinger's early papers, you had

00:07:30 to be a good deal better German than I ever was to understand them, but if you could dig

00:07:35 it out it was all there and he was right.

00:07:39 But most people didn't believe him, they thought even some of the people, the men in this country

00:07:43 that ran the bakelite organization didn't, up until way along the late 20s, didn't believe

00:07:52 that bakelite was a polymer, a macromolecule, it was some kind of a mystic thing held together

00:07:59 by unusual forces.

00:08:02 So it wasn't well accepted.

00:08:05 But finally people began to accept his views and the thing got started along a little better.

00:08:15 I got introduced into polymer chemistry more or less by accident.

00:08:19 There was nobody in the universities in polymer chemistry in my day in 1920.

00:08:25 As a matter of fact, in 1900, I think there were less than five organic professors in

00:08:31 major universities that were doing research in organic chemistry.

00:08:35 There just wasn't any chemistry in this country and there was a little industry, but none

00:08:41 in the university.

00:08:43 And nobody was working in polymer chemistry.

00:08:46 Well I was running a reaction with Martin Frederick trying to make a pent alkyl arsenic

00:08:52 compound by condensing lithium ethyl and tetra ethyl arsenic chloride.

00:08:59 The reaction took off all right and we got triethyl arsenic, plus gas.

00:09:07 Now we analyzed the gas, it was about 95% ethane, 5% ethylene, and I defy you to write

00:09:17 an equation that will produce that.

00:09:22 You could account for all of it being ethane and ethylene 50-50.

00:09:27 You could account for it being butane, but there's no way to say that it would be essentially

00:09:32 all ethane and very little ethylene.

00:09:37 Being rather naive, I postulated that our excess lithium ethyl had polymerized the ethylene

00:09:46 and it had disappeared as a gas from the reaction mixture.

00:09:51 So I thought, well maybe I better prove that will happen.

00:09:54 So I put a little lithium ethyl in some Nujo, pumped in ethylene at room temperature, let

00:10:01 it stand for a couple of days, and out on top came a nice white powder of polymer.

00:10:07 Well undoubtedly that was the first linear polyethylene that anybody had ever seen.

00:10:12 But nobody was interested in polyethylene at that time.

00:10:16 So it just went off as a little note in the journal, here's polyethylene made by lithium

00:10:24 butyl polymerization.

00:10:26 Some people in the industry took a look, didn't get it to go very well, and that was the end

00:10:30 of it.

00:10:31 Until a few years later, the British found out how to polymerize it under pressure with

00:10:37 a peroxide catalyst.

00:10:39 And now we make a few billion pounds a year of polyethylene, high pressure polyethylene.

00:10:45 But the low pressure polyethylene came along much later.

00:10:50 I had another experience shortly after that that got me further involved in polymer chemistry,

00:10:55 and we were trying to find out what polymers were then.

00:10:58 We were making bromoalkyl dialkylamines, and I was going to use those to introduce

00:11:06 a dialkylamino group into a triamine group into other things through the bromine.

00:11:14 But the darn things kept reacting with themselves.

00:11:17 And I got polymeric materials, or I didn't know whether they were polymeric, but I got

00:11:21 condensed materials, which had some active halogen and some ionic halogen, some non-ionic

00:11:28 halogen.

00:11:30 By comparing the amount of non-ionic to total halogen, I could make an estimate how much

00:11:36 had reacted with itself to give the products we had.

00:11:40 And we found out that this was dependent on the distance between the bromine and the nitrogen

00:11:45 and the nature of the alkyl groups and all, and we worked on that for about eight or ten

00:11:50 years until we got pretty well straightened out what we could expect.

00:11:54 And there was some cyclization and some chaining out, but nothing exciting about it, but at

00:12:01 least we began to understand what the reaction was, and we made some synthetic polymers.

00:12:09 About this time—this was long, about 1933—I was hired by—it was 1928—I was hired by

00:12:16 DuPont as a consultant.

00:12:19 This is an interesting story, because DuPont wanted Roger Adams as a consultant, and Charlie

00:12:27 Stein said, we want you to come down once every month to keep us straight.

00:12:34 Roger said, oh, that's too damn much traveling from Abaddon these days, train travel.

00:12:40 I won't do it.

00:12:41 So after they argued for a while, Roger says, why don't you hire two of us?

00:12:45 One will come on one month, and Stein says, fine, who's the other one?

00:12:50 And I got the job as the other one, but he didn't know who I was, neither did anybody

00:12:56 else, but at least I got a consulting job then, and I've had it ever since.

00:13:00 Well, on one of my early trips down there, I talked to Elmer Bolton about this matter.

00:13:10 He brought out a book by Carlton Ellis, which had a place in it that said, here's a reaction

00:13:18 between sulfur dioxide and ethylene, propylene, butylene that'll give a polymer.

00:13:23 He said, do you think that reaction will take place?

00:13:25 I said, it doesn't look right.

00:13:27 I said, that's not orthodox organic chemistry.

00:13:30 I don't think that'll happen.

00:13:31 Well, he said, now just imagine, if that happened, sulfur dioxide, $5 a ton, ethylene, two cents

00:13:40 a pound, that would be a good plastic, and we ought to know about it.

00:13:44 Well, I said, why don't I go back to Urbana and see if I can put them together and get

00:13:49 it?

00:13:50 I didn't think it would work, and I couldn't work with ethylene because we didn't have

00:13:54 any high-pressure equipment, but we did work with cyclohexane and butylene and one or two

00:14:00 others, and sure enough, with a little peroxide catalyst, those two reagents, olefins, SO2

00:14:08 react to give sulfones.

00:14:11 They were very pretty white products.

00:14:15 They looked beautiful.

00:14:16 It was as good as nothing with acrylate, for example.

00:14:20 But when you melted them to get a poker chip, that's what we always tested them as, always

00:14:26 there was one star in the middle of the thing.

00:14:29 Just a little decomposition of the polymer back to sulfur dioxide and then the hydrocarbon,

00:14:37 which give a little bubble and a little star and thing.

00:14:41 You never could get a good molding, and nobody ever has yet.

00:14:45 I mean, a lot of people spent money on it and haven't done it.

00:14:49 All of the polymers were one-to-one of SO2 and ethylene or olefin, except vinyl chloride,

00:14:57 and that invariably turned out two vinyl chlorides to one SO2.

00:15:01 Well, later on, the British, I forget his name now, he said we were all wrong, that

00:15:10 there was two styrenes to one SO2.

00:15:14 They argued about that for a while, but what they found out was that we were both right,

00:15:18 just depending on what temperature you ran it.

00:15:20 You ran it at his temperature, you got two styrenes and one SO2.

00:15:23 You ran it at ours, you got one styrene and one SO2 in each polymer.

00:15:28 They weren't any good anyway.

00:15:31 But we spent about ten years studying that polymerization reaction, determining that

00:15:37 they were head-to-tail polymers, one primary cell phone, one secondary cell phone, unstable

00:15:46 to alkali, and no one ever found a stabilizer for that product.

00:15:53 As a matter of fact, they never had any use until a few years ago.

00:15:57 Bell Telephone found they had just the property they wanted.

00:16:01 They wanted to make a polymer which would decompose completely when they got ready for

00:16:05 it to.

00:16:06 So they made molds out of SO2-olefin polymers, built their other product in, and then heated

00:16:13 up and got the molds off and got the products they wanted.

00:16:16 So they finally developed the use for SO2 polymers after about forty years.

00:16:23 Now about this time, Carothers was hired by the DuPont Company at the experimental station,

00:16:32 and he began his classical work on polymerization.

00:16:36 I might mention that a lot of people have thought Carothers was hired by DuPont to make

00:16:43 synthetic fibers, and even some of the people in DuPont tell that story.

00:16:48 But that's not a true story.

00:16:49 I know because I talked to Stein about this job.

00:16:52 In fact, he offered it to me, and I said I didn't know enough to do it, and I recommended

00:16:57 Carothers to be hired.

00:17:06 The only requirement was you come in and do fundamental research and find something useful,

00:17:12 and that was the way Carothers was hired.

00:17:15 Carothers had been two years on our staff at Urbana and had gone to Harvard for a year.

00:17:20 He wasn't very happy in the Hallowed East.

00:17:23 He was a Middle West farmer.

00:17:25 He was ready to leave and went back to DuPont without much argument and started work there

00:17:32 in the Purity Hall.

00:17:35 That's what all the rest of the people in DuPont gave a name to the laboratory, where

00:17:39 Carothers and his group of about six people went to work on fundamental organic chemistry.

00:17:46 They worked a little on organic metallic compounds and then started them to work on polymer chemistry,

00:17:51 and that was Carothers' own choice of a subject to clear up.

00:17:55 He decided it was a complicated subject, a useful subject, and one that if he would dig

00:18:01 into he could make something contributing.

00:18:06 I don't know how many of you remember back to that day, but he went to work in 1928.

00:18:12 About two or three years later, he wrote a chemical review article on polymers, and after

00:18:20 that article came out, there was no mystery about polymers.

00:18:25 It was all laid out there in first class, plain English that even I could understand,

00:18:32 Staudinger in German.

00:18:34 But he proved beyond a doubt that Staudinger's ideas of macromolecules was right, and he

00:18:40 synthesized them by a step at a time until he got the products that were macromolecules.

00:18:48 That gave us the idea of what an end group was, what a recurring unit was, what a copolymer

00:18:54 was, what a condensation polymer was, and all of these points were cleared up.

00:19:00 This was extremely important, and I've said that any ordinary chemist could then go into

00:19:07 work in polymer chemistry and make contributions because you could do what you were supposed

00:19:12 to do. You knew what needed to be done, and some of the rest of us got in the game and

00:19:18 could make progress.

00:19:20 But if you knew Carothers, he was probably, I would say, the smartest, keenest chemist

00:19:28 in organic chemistry that I have ever known of. In over 50 years, I've known an awful

00:19:34 lot of them, and I still would put him number one. And the only other man I could compare

00:19:40 with him in quality of brain power was one Peter Debye, who was a physical chemist at

00:19:49 Cornell in Hull, Illinois. Those two men stood up above the rest of us. There was no comparison.

00:19:56 They were way up there.

00:19:58 Well, Carothers' work in the condensation polymer soon led to hexamethylene adipamide,

00:20:05 which developed in the nylon, and not very long after that he came through with one polymer

00:20:15 of vinyl acetylene to give chloroprene and neoprene. Well, Julian Hill was one of the

00:20:23 men working with Carothers, and Paul Flory was another one. Paul Flory had never had

00:20:30 any polymer chemistry in his studies at Ohio where he got his degree, but his first job

00:20:38 was with Carothers. And he got in there just as they made these two discoveries, and I

00:20:44 may say that polymer chemistry was high in that series about the time they had the first

00:20:49 nylon and the first neoprene ready to advertise to people, and it was a very, very exciting

00:20:56 time. And I was a consultant, and I got to live through some of that day.

00:21:02 But that, a lot of interesting things happened. Carothers had about six or eight good men

00:21:13 working with him, and he would lay out the programs and they'd do the work. That's the

00:21:18 way it always is. The professor, you know, never works, and the research director doesn't

00:21:22 either. The other people do the work. But Carothers did the thinking. And Hill was one

00:21:29 of the men working with him. They made hexamethylene adipamide. It didn't seem to be anything unusual,

00:21:37 no good. They didn't even bother to get a patent on it. And to this day, DuPont does

00:21:43 not have a composition of matter patent on nylon. They published it, let it go, and got

00:21:51 it in the public domain. But they had an accident. I guess you'd call it an accident. They found

00:22:01 what you'd call cold drawing. I haven't got a sample of it, but cold drawing, if you stretch

00:22:09 a polymer, it comes out, orients itself, and it's different. Well, the way they discovered

00:22:16 this was Julian working in the laboratory with polyesters. Now, they're softer and are

00:22:24 easier to handle. And so after the amide was put on the shelf, it went back to polyesters,

00:22:32 and he got some of those, and he got a little bit on the end of a rod and pulled it out

00:22:37 and noticed that it'd string out. And it looked kind of silky, and they were interested

00:22:42 in this. Well, one day Doc went downtown, and Julian Hill, Jim Kirby, Spanning going

00:22:53 two or three other boys, got playing horse. They got some of these nice polymers. They

00:23:01 get a ball on the end of a rod. They get out in the hall like this, run down the hall and

00:23:07 see how far they can stretch it. And when they stretched it far enough, all of a sudden

00:23:13 they noticed it was silky. And it made a lot of good-looking silk out of those polyesters.

00:23:19 Well, the polyesters were all too low-melting to be fibers, for textile fibers. But when

00:23:25 they found they could cold-draw these things and make strong fibers out of them, they thought,

00:23:30 well, let's go back to the amides and see. And then they found out they could cold-draw

00:23:34 on nylon, and there was polymethylene, hexamethylene, and there was nylon. And that really, the

00:23:43 cold-drawing patents were the things that made synthetic polymers. Without the cold-drawing

00:23:51 and orientation, you never had a good fiber. But that made the fiber, and that was a thing

00:24:00 that protected DuPont to give them a chance to develop nylon and come out alive.

00:24:06 The one other thing I will say, that it was touch and go whether they would make nylon.

00:24:14 It was going to be too damn expensive. They just never could sell it. And you don't know

00:24:24 how close it came to being turned down. And really, that's what made the DuPont company.

00:24:31 It wasn't much of a company before they got that and got going. That's where they made

00:24:35 all their money.

00:24:35 And it still is a very big product for them. And it's still a very big product for them.

00:24:44 But that little horseplay in the lab, stringing them out down the hall, running to see who

00:24:54 could get the longest stretch without having to break, was the thing that made cold-drawing,

00:24:59 and that's the thing that brought in the fiber.

00:25:05 Well shortly after the introduction of nylon, the British calico workers discovered that

00:25:11 ethylene terephthalate made a good fiber. Well now Carothers had worked with polyesters

00:25:16 too, and had made practically every one of them except the terephthalic. At that time

00:25:20 terephthalic acid was an intractable, expensive, unavailable material that nobody ever thought

00:25:27 to be any good. But about that time they found out how to make it cheap, and then they found

00:25:31 out how to make ethylene, and the calico workers developed terephthalate.

00:25:36 And DuPont, Emmett Izzard, working at Buffalo for the film department, found out he could

00:25:44 make a polymer out of it, and if he biaxially stretched it, he got dink on the good film,

00:25:54 which is now the major film for most of the uses of the photographic industry.

00:26:07 It's the most important film there is, very stable, very useful, and that was the one

00:26:14 polyester that Doc missed. All the rest of them hydrolyzed too easy, but that one didn't.

00:26:21 But still they managed to get in, get mylar and Dacron, and make use of it. It wasn't

00:26:28 very long after the Dacron development that they found out that polyacrylonitrile could

00:26:34 be a vinyl polymer, could also be fabricated in the film. And that's one I had a little

00:26:41 bit to do with because we had worked with polyacrylonitrile and found that we could

00:26:47 dissolve it in dimethylacetamide, and they'd been working for two or three years and hadn't

00:26:51 got a solvent. So I said try it, dimethylacetamide. Well they tried it, and it didn't work. About

00:26:59 ten years later we found out the reason it didn't work. They'd used dimethylacetamide,

00:27:06 which was 50 percent acetic acid. That mixture forms a constant boiling mixture, which boils

00:27:14 the same place dimethylacetamide does, and they were confused about it, and so they missed

00:27:20 dimethylacetamide as a solvent. But that put them on the right track, and they went and

00:27:24 used dimethylformamide and developed their polymer from that. Later the Monsanto people

00:27:33 took up dimethylacetamide and wet spun their acrylam from that. At any rate, that was the

00:27:41 third big synthetic fiber that came out of that group indirectly. The nylon was Carothers'

00:27:48 work, and the other two followed from other parts of the company. While Carothers was

00:27:55 working on this group, he didn't do much except on condensation polymers, but there was one

00:28:02 vinyl polymer they did develop, and this was the discovery of the first synthetic rubber.

00:28:09 If you go back and look at the history, you'll find there's a paper from Father Newland at

00:28:15 Notre Dame describing the dimerization and trimerization of acetylene to make vinyl acetylene

00:28:23 and divinyl acetylene. Well, these are very interesting materials. Calcutta DuPont Laboratory,

00:28:31 Jackson Laboratory, looked at those unsaturated compounds and said, they ought to be good

00:28:35 for something cheap. I want to develop those, and they went out and bought up the patent

00:28:40 rights from Father Newland, and they spent about three or four years at Jackson Laboratory

00:28:45 trying to make something useful out of it. They did get some pretty good drying oils

00:28:54 out of divinyl acetylene. They made pretty good drying paints, but they had one very

00:29:01 serious fault. When the paints dried, they developed peroxide, and about the next thing

00:29:06 you knew, they'd touch one of them and blow up. So it didn't somehow turn out to be a

00:29:11 practical discovery. As a matter of fact, today in this company, there's a company rule

00:29:19 that says you don't do any research on divinyl acetylene because you're going to get hurt.

00:29:27 All of the extra stuff was pushed back and burned up right away because it was too dangerous

00:29:31 to handle. Well, at any rate, after about two or three years of failure, Calcutta got

00:29:40 acquainted with Doc and came over and says, how would you like to work on these compounds?

00:29:45 They're kind of interesting. Don't you want to study them for polymers? The guy said,

00:29:50 yeah, I think I'd like to. He said, bring me over something. So they brought him over

00:29:55 a mixture and he purified them up. He had a fellow named Arnold Collins working for

00:30:01 him. He put him to the job of distilling a mixture of them and getting them pure. This

00:30:06 was on a Friday afternoon. Arnold was distilling this mixture and out came the monovinyl acetylene

00:30:13 and another little fraction of divinyl acetylene. Instead of cleaning up his mess and going

00:30:20 home with the two pure products, he left the in-between fractions standing on his desk

00:30:25 until Monday. When he came back Monday, it had solidified. Then getting it out of the

00:30:31 flask, he found there was rubbery in it. He dropped it on the table and it would bounce.

00:30:36 That was the first neoprene. They didn't intend to make any rubber. They weren't trying to

00:30:44 make rubber. They were just studying reactions, the purified product. What they found out

00:30:49 was that in making the monovinyl and divinyl acetylene, they had an acid catalyst and a

00:31:01 little HCl was in there. Some of the HCl had added to monovinyl acetylene. This fraction

00:31:07 they got out was really the hydrochloric acid adduct. Well, this hydrochloric acid adduct

00:31:14 went through a whole series of transformations. It first adds on 1,4 and you get a chloroalline.

00:31:21 Let that stand a little while, it reorients and you get a 2-chlorobutadiene. Let that

00:31:25 stand a little while, it polymerizes and then you get the polymer. All that had happened

00:31:30 over the weekend in this flask. They had to go back and unravel all of this. But if he

00:31:35 hadn't been curious enough to look at that sample on Monday morning and had just gone

00:31:40 and thrown it away, well, they wouldn't have done it. They're synthetic rubber for a good

00:31:45 long while probably. And they weren't trying to make synthetic rubber. They were just studying

00:31:50 reactions. Later on, he added HCl directly and found out what all the steps were and

00:31:57 they developed their process. They don't make neoprene from vinyl acetylene anymore because

00:32:04 that's a little too dangerous. They've had too many exposures to that. But they got some

00:32:09 trick ways of making it out of butadiene now. They get chlorobutadiene from that and

00:32:16 their neoprene is made from that and it's still the best, strongest, oil-resistant rubber

00:32:23 that there is on the market. Now there are cheaper ones made and I've always wondered

00:32:28 why they didn't run neoprene out of business. But I guess they're just not quite good enough

00:32:33 to do it.

00:32:37 Well, while Corolla's work was mainly on the condensation polymers, vinyl polymerization

00:32:44 got into the other field, other laboratories, and some considerable amount of work was done

00:32:51 there. They finally did divide that it was a stepwise reaction, that it was a chain reaction,

00:32:59 that the first was initiation and propagation and termination. When they recognized those

00:33:05 steps and controlled them, they began to find out how to make polymers from vinyl monomers.

00:33:13 One of the big developments right there was by Mayo and Walling at the U.S. Rubber Company.

00:33:19 They were so good at making theoretical stuff they got fired because it wasn't practical

00:33:23 enough. But they did discover the process of reactivity ratios so that you could know

00:33:33 how the things would polymerize and they could make the right mixture to start with to get

00:33:38 the composition you want. If you take vinyl chloride and vinyl acetate, mix them together

00:33:43 and polymerize them until you get 100% polymer all together, don't change it, and you analyze

00:33:49 it, at about a halfway stage you find all the vinyl chloride is gone, the last half

00:33:54 is pure vinyl acetate. Well that's not giving you a very homogeneous polymer. But if you

00:34:01 learn how to add the vinyl chloride a little at a time, you can get a homogeneous polymer

00:34:05 of the composition you want. Now it's interesting to know that the people at Union Carbide who

00:34:12 developed the vinylites knew all of that, but they hadn't recognized the fact that this

00:34:17 was a business of reactivity ratios. They had learned how to control the add-ins so

00:34:23 they got the right things, but it was Mayo and Walling that made a theoretical discovery

00:34:28 that other people could make use of in any of these studies. And that was one of the

00:34:32 big problems. Another thing that came in about that time in which we had quite a little hand

00:34:40 was Staudinger, by pronouncement, had said that the polymers of the vinyl type were head-to-head

00:34:50 polymers. If you went back and looked at it, you couldn't find any evidence for it, but

00:34:55 that's what he said they were. And again, he was right. But nobody knew whether he was

00:35:01 right or not. So we spent quite a lot of time working on that problem and did by chemical

00:35:07 means. You didn't have any black boxes in to do all this for you. You had to do it the

00:35:13 hard way. But we found out that most of these things were head-to-tail recurring units went

00:35:20 together and there were a few that were not that way. One of them was polyvinyl acetate,

00:35:27 which you hydrolyzed to polyvinyl alcohol, and Flory demonstrated that the polyvinyl

00:35:31 alcohol has a few head-to-head, tail-to-tail units in the alcohol. And this he did by using

00:35:38 pyridate oxidation. Now if you study the amount of pyridate that's used, you come up with

00:35:46 such little variation that you don't think any happened. But he had enough sense. We

00:35:52 didn't have enough sense. We tried that. We said they were still the other way. But he

00:35:56 had enough sense. Instead of doing that, he studied the viscosity of the product after

00:36:02 he had treated with pyridate. And it was just about half as big as it had been before he

00:36:06 treated it. In other words, it was about the middle of the place. It was a place that split

00:36:10 in two and you got two products. And there is a certain amount of polyvinyl acetate that

00:36:16 goes together head-to-head, tail-to-tail when you hydrolyze it that comes out. Now whether

00:36:21 that is because the polarity is such that it doesn't matter much which way the radical

00:36:29 adds or whether that's where the react stands by dimerization, nobody is quite determined

00:36:35 yet. But at any rate, there is a little head-to-head, tail-to-tail stuff there. And the other place

00:36:41 where they found it is in the polyvinyl fluoride. In polyvinyl fluoride, there is a certain

00:36:46 amount of the chain in which the fluorines on are adjacent carbons, which means that

00:36:53 some of them add in the backside two directions. And that again is because there isn't enough

00:36:59 difference in the polarity of the two to determine which way the free radical adds and goes on.

00:37:06 But those are about the only two that show that this is. In this other thing they determined

00:37:14 was the business of putting in chain transfer agents which would control the molecular weight

00:37:22 and would put an active end group on polymer chain so they could build it up and get an

00:37:29 end group and do something else with it if they wanted to. Telemerization they called

00:37:33 it. Now in addition to free radical polymerization, cationic and anionic emission came in. And

00:37:41 these were effective sometimes when free radical wasn't. And isobutylene, for example, which

00:37:50 is butyl rubber, doesn't polymerize well with free radical, but it does go well by cationic

00:37:55 polymerization. But you must drop it down to about minus, oh, minus 30 or 40 degrees

00:38:02 to get a good polymer. The cationic polymerization, if you run it at room temperature, you got

00:38:07 to get dimers, trimers. Run it about 20 degrees below zero and you get maybe 20 or 30,000.

00:38:15 Run it about minus 60 and if you're polymerizing isobutylene, you fill a tub with isobutylene,

00:38:23 cool it down, break a catalyst in it, stand back and hold your hat because it all polymerizes

00:38:30 and there's the big 100,000 molecular weight polymer formed quickly, very quickly. And

00:38:37 it's characteristic cationic polymerization, also vanionic. They go better the lower the

00:38:43 temperature because you get more active species.

00:38:47 Now during this time, all of these things were studied actively by industry and the

00:39:00 most of the useful polymers, these cheap polymers like vinyl chloride, ethylene, vinyl

00:39:07 ethylene, styrene and all those things had been developed. For example, polyvinyl chloride

00:39:13 was one of the early ones that Carbide worked on. But during this time, Seaman at Goodrich

00:39:21 had learned a trick that nobody else had observed and that is that you can plasticize polyvinyl

00:39:25 chloride. Now polyvinyl chloride itself is kind of a cruddy, hard, breaks apart, doesn't

00:39:34 do well, but if you load it up with tricrystal phosphate and tributyl phosphate, some of

00:39:39 those things, then you can get a semi-rubbery product and that's the one they're making

00:39:44 a few million pounds a year, I mean a few million tons a year now to do all the things

00:39:50 that they want with polyvinyl chloride.

00:39:52 Tricrystal phosphate, diethyl phthalate, those are the two main plasticizers. And of course

00:39:59 that's spilled over and they use it for other places where they need to soften a polymer

00:40:05 and get it into a more useful form.

00:40:10 One of the major advances in polymerization practice I guess came during the government

00:40:16 rubber program which started in 1941. Some of you remember I think that one day in December

00:40:24 1941 we suddenly woke up to the fact we had no place to buy rubber. The South Pacific

00:40:32 was cut off, we couldn't get it, and while we had a fairly good stockpile, we didn't

00:40:36 have enough to fight a war on and we had to develop very quickly a rubber supply. There

00:40:44 was a rubber bazaar set up in Washington who had the authority to give the rubber program

00:40:50 any raw materials it needed, any priorities it needed to build plants and all of that.

00:40:57 And then they put Bradley Dewey, who was Dewey and Almey in charge of the research program,

00:41:04 and he had the good advice of Ed Gilliland who was a chemical engineer, well-trained

00:41:09 and he's a chemical engineer and a little organic chemist at a place called the University

00:41:14 of Illinois. And he was a very, very competent man and he told Brad Dewey what to do and

00:41:22 the result was that he came out with a good group of people to work on it. He, in a very

00:41:28 short time, put together a team with all of the various rubber companies, Kipton, Goodrich,

00:41:36 Goodyear, Firestone, U.S. Rubber, General Tire, one or two more, Industry, Exxon, which

00:41:46 was then Esso, and Bell Telephone, I don't know whether all of them were there, and then

00:41:53 the universities, there was Massachusetts Technology, Cornell, Case Western, Chicago,

00:41:59 Minnesota, and Illinois. And all of these people had research teams. I remember I was

00:42:05 in Washington at just about the time this thing set up. Brad Dewey came to me and said,

00:42:11 We want you to start a team on it. You're the only university man that's really had

00:42:16 polymer experience. And about that time, I was damn mad at the National Defense Research

00:42:24 Committee because they'd given me some stinging jobs and called me back to Washington a few

00:42:30 times while I was trying to get home and rest. And I told them to go too. I wasn't going

00:42:35 to work for them anymore. And I told Brad Dewey, I wasn't either. Oh, he says, You've

00:42:39 got to. He says, You're the only one that can do it. Well, I said, Give me $100,000

00:42:42 next year and I will. Next morning he had it and I had to go to work. Well, at any rate,

00:42:49 that was one of the most successful projects that I know of was a government project. The

00:42:57 people worked together beautifully. There was no jealousy between the groups. They

00:43:05 come from all these places and they pitched in and worked hard. I remember telling Robert,

00:43:12 what's his name, at Bell Telephone, who was one of the ones that helped, that if we can't

00:43:18 do better than the tree does within a year, we're a bunch of poor chemists. And by the

00:43:24 end of the year, we did have a rubber that was perfectly good. It wasn't the best one

00:43:28 that ever was, but it satisfied all the needs. The other interesting thing is that chem engineers

00:43:34 build plants and they didn't know how we were going to make rubber. But when we got to going,

00:43:39 all of those plants gave better than 140% capacity yield on what we were doing. So we

00:43:48 had plants that produced without knowing how we were going to do it. And I think we had

00:43:53 an awful lot of luck. But we also had a lot of good people working and it was complete

00:43:59 cooperation. There was no trying to hog credit for it. There were no patents saved. Everybody

00:44:07 threw stuff into one pot. We used to have a lot of meetings. One of the favorite places

00:44:13 to meet was out at the University of Illinois and I found out, I think, why. After our meeting,

00:44:19 we generally went out to my house for a few drinks and they decided I could make the best

00:44:24 old fashioned. So from there on, the meetings generally were held in Urbana. So after the

00:44:32 meeting, we could enjoy ourselves. But we had, within a year, we had a rubber that was

00:44:39 perfectly satisfactory, although not a world beater. At the end of the hostilities, the

00:44:47 Office of Rubber Reserve sent five chemists and one of the men from the office to Germany

00:44:53 to see what happened over there during the war. And there's where we learned about redox

00:44:59 polymerization, which is a fast polymerization. Well, the Germans had been trying to develop

00:45:05 redox polymerization to make a continuous process to make rubber from butadiene and

00:45:10 styrene. Oh, I forgot to tell you one other thing I ought to. We knew that the Germans

00:45:17 were using butadiene and styrene and had a little bit of inside information on that when

00:45:22 we started because the Esso people had been behind their back trading a little bit with

00:45:29 the Germans. And they caught hell from the government for doing that, but it was an awful

00:45:33 good thing somebody did it because it gave us a good big start on our rubber program

00:45:39 to have an idea of what we ought to use. And so although they caught hell for trading with

00:45:45 us, that information was damn valuable to us. Well, at any rate, let's go back to this.

00:45:51 The redox polymerization was trying to make it continuous and fast so you could pump it

00:45:56 in one way and pump the rubber out the other. But this didn't quite satisfy our needs, and

00:46:05 we developed a fast process for low temperature. And we had found in our experiments that if

00:46:11 you make this polymer at around about zero to five degrees, it was a better rubber. It

00:46:18 was narrow molecular weight. It was a better, it stood up better in actual use. And that's

00:46:25 where we developed the so-called rubber program that we finally ended up with and are now

00:46:31 using in industry to make what, I don't know what to call it now. It was GRS. I think it's

00:46:38 SGR or something like that. They turned it around a new name since the war is over, but

00:46:43 it was styrene butadiene government type originally. But that rubber is the one that is used for

00:46:51 practically all passenger cars today. It's not satisfactory for big bombers or for truck

00:46:58 tires because there's a little too much heat buildup in using it. But for others, it's

00:47:04 perfectly satisfactory, and it's the one we use. And we'd use even more of it if the damn

00:47:10 OPEC didn't kind of whoop up the oil prices too much. That's where the trouble is right now.

00:47:15 And by the end of the war, before this whole program ended, two of the companies had

00:47:23 developed polymerization of styrene and butadiene with a Ziegler type catalyst, which I'll

00:47:31 mention a little later. And they were able to make a rubber which was exactly equivalent

00:47:39 and also by lithium polymerization they were able to make a rubber that was essentially

00:47:47 exactly equivalent to natural rubber. And this was actually produced in competition with

00:47:54 natural rubber right after the war and would still be doing except again. You had to use

00:48:00 oil, and when they put the prices up, squeezed it out, and we had to go back to using natural

00:48:06 rubber for the big tires. And they will use that until things clear up and we get this

00:48:13 oil price down to where it ought to be. But that discovery came just at the end of the

00:48:22 war, and we never used it in the wartime, but we do know how to make all the rubber

00:48:27 we need as good as you can make from a tree if you have the oil to do it. You can polymerize

00:48:37 at low temperature now as fast as we used to do it at 70 degrees and you can get a better

00:48:44 product. During all this time there was one other development that I should mention. In

00:48:52 1946 Professor Mark brought out his Journal of Polymer Science. That was the first polymer

00:49:00 journal we had to get our information together. And a few years later in 1966 the Journal

00:49:06 of Macromolecular Chemistry came out. Then the American Chemical Society in 1968 started

00:49:13 macromolecules. And all these publications have done a lot for the polymer field to give

00:49:20 you a place to put your information, find it, and use it. And they've been great promoters

00:49:27 for polymer science. Mark, I think, was great service to the polymer industry in this country

00:49:35 has been his promotion. I would say I'd rate him as a promoter of polymers. He made people

00:49:42 aware of what they were and where they were useful and has helped it from that standpoint.

00:49:48 Most of his actual research in polymers was done before he came to America. But his spreading

00:49:54 the gospel has come over here and he has done a wonderful job at it.

00:50:00 Well, a few other little things since then might be worth mentioning. The NADA Ziegler

00:50:06 system came out with aluminum alkyls, titanium chloride. A little accident on the part of

00:50:13 Ziegler using a dirty cylinder to run his polymerization to try to make long-chain olefins

00:50:22 gave him polyethylene, which is a low-temperature polymerization of ethylene to give the high-density

00:50:30 polyethylene. And, of course, NADA found out that some of it was tactic and some isotactic

00:50:37 and that developed a lot. And that's also a very useful thing that has happened. And

00:50:44 by using ethylene and propylene, you can do that with Ziegler's catalyst where you can't

00:50:50 do it with radicals. And if you put in another third olefin that's got a double bond somewhere

00:50:57 else down that don't polymerize, then you can make ethylene, propylene, and the third

00:51:00 one. And you got a new rubber, I forget what they call it, but it's a pretty good rubber

00:51:06 and you can use the second with a double bond hanging off the side for vulcanizing

00:51:11 and all the rest of it is saturated so it doesn't oxidize so easily. Then there was

00:51:17 the accidental discovery of Plunkett who was trying to work on tetrafluoroethylene. He

00:51:24 had the stuff and he had the cylinder and it looked like it ought to polymerize. He

00:51:31 worked on it, couldn't get anything. One day he went back to get his cylinder, couldn't

00:51:36 use it, couldn't get any gas out of it. It weighed enough to have been in there. So he

00:51:42 took his hacksaw and opened it up and there was polymerized tetrafluoroethylene and that

00:51:48 came out of that discovery. Again, it shows that it pays to be a little curious. If you

00:51:54 just let it go aside and said, well, there wasn't anything in there anyway, well, we

00:51:58 wouldn't have it. But when they found out it would polymerize, then they found out how

00:52:02 to do it. But that was a very important discovery. Another one of the discoveries that is worth

00:52:09 noting, I think, is styrene. Dow had been making polystyrene, but my understanding is

00:52:17 polystyrene was never a very good plastic until they got the very pure styrene that

00:52:24 they were making during the war for rubber. There, the styrene coming out of the distillation

00:52:31 columns where they were making it was about 99.5 percent pure. And when they polymerized

00:52:39 that, they got a good polymer. And then it soon went up to the billion pound a year

00:52:47 product. Another development, come along in here, I'm not going to give you all the

00:52:52 details of these, was Shell's work on the epichlorohydrin to give the adhesive materials

00:53:03 epoxies. And that's a very important development that they did. And they found that as a byproduct

00:53:09 of their making synthetic glycerin. Then the polyurethanes came in. And another development

00:53:17 was Rothschild's polysilicones that came in the late 40s and early 50s. And they did

00:53:24 some very excellent work there. And then the government decided they needed some high temperature

00:53:32 polymers. And a lot of that was supported by the Wright-Patterson Air Force Base. And

00:53:39 also a lot of it was done at DuPont. Smog. Strug developed Nomex and below it his aircraft

00:53:50 has developed a polyimide with acetylene N-groups. That's been studied for the Wright-Patterson

00:53:57 and that gives a very good high temperature material. In 1961, Herbert Vogel, working

00:54:04 with me at Urbana on an NSF project, found out how to make PBI, polybenzimidazole. And

00:54:13 as far as I know that still is the best high temperature flame resistant fiber that anybody

00:54:21 has ever made. It's a little expensive yet. But I was told at this meeting by the people

00:54:28 selling it, we finally decided we're going to make it and see if people won't buy it.

00:54:35 It's going to be a little expensive, but the only way we're ever going to get in the market

00:54:39 is to put out enough of it so people can have it. So that's going to come on the market

00:54:44 for study. And it certainly is one of the first ones that's been floating around now

00:54:51 since 1961, but they're about to decide to manufacture it in a large scale.

00:54:58 Silly's Polyquinoxones is another one of the developments. And that's a very fine adhesive,

00:55:04 which I think Boeing used in their honeycomb structures and airplane structures. And these

00:55:14 polymers are now being studied all over the world, Berlin, Corsac, Russia, Hergenrother,

00:55:20 and various parts of this country. Yoda and his group in Japan are working on those.

00:55:25 So all sorts of high temperature polymers are underway. The most recent thing at DuPont

00:55:32 was their Kevlar, which probably you heard Stephanie talk about yesterday, from ethylene

00:55:40 terephthalate, I mean terephthalic acid, and tetraphenylenediamine, the material that is

00:55:47 an excellent tire cord material, much better than steel, much stronger for weight for weight.

00:55:59 The one thing that I would stress to any of you who works in this field, more money,

00:56:05 research money, has been wasted by trying to polymerize impure products than any other way.

00:56:12 If you want to make a polymer, start with a pure material. Thank you.

00:56:19 Applause