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Oral History Transcript — Dr. Maurice L. Huggins

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Interview with Dr. Maurice L. Huggins
By J. Knox
In Santa Barbara, CA
January 11, 1976

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Maurice Huggins; January 11, 1976

ABSTRACT: Topics discussed include: Kodak Research Laboratory, polymers, Society of Rheology, Stanford University, x-ray diffraction, Arnold Bondi, hydrogen bonds, and viscosity theory.

Transcript

Knox:

This is an interview with Dr. Huggins, on the afternoon of January the 11th, in Santa Barbara, Calif. at the Miramar Hotel. (That's just to make sure we have that.) Ok, Sir, you were saying that the point that you wanted to establish was that you really didn't have that much — I think it's what you were saying in the beginning — with the Society of Rheology. I think that's what you were about to say, wasn't it?

Huggins:

I had nothing. I had nothing to do in the early days with the Society of Rheology and very little later. I knew, in the early 1930's at least, that there was work going on in this field, especially by Professor [Eugene C.] Bingham. I knew a little about it. I was teaching physical chemistry courses, and I had to know some things about these things. I remember visiting Professor Bingham one time, and learning a lot about his work and his ideas, and being favorably impressed. I learned about the name "rheology”. Then, a number of years later, I began going to some meetings of the Society, and presenting some papers. This was after I became involved in theories of solutions of linear polymers. But I do not remember that I had any connection, official connection or unofficial connection, other than going to the meetings with the Society of Rheology. I may have been a member for a few years. If I had any position at all, it was a very minor one, such as on the editorial board for the RHEOLOGY BULLETIN or something like that. I know I did communicate some, at least a letter to the editor of the RHEOLOGY BULLETIN. I can't remember what it was about. Perhaps something more I do not remember.

Knox:

Yes. Well, I'll refresh your memory, at least as much as I can. As I mentioned to you before, in part what we want to do is a history of rheology as much as we do a history of the Society, and I don't think we can say that you didn't have very much to do with rheology. That's a totally different situation than the Society, really, at least as I read the literature. But let's go back a little bit. When you first went to college, did you have any idea at that stage of the game — because as I recall that was not too many years from the early work that [Hermann] Staudinger had done on polymers? But your early work was on the structure of polymers, as I recall and was in X-ray diffraction and on structure of molecules and atoms.

Huggins:

Right.

Knox:

And I guess the earliest record that I can find of your established works was a review that you did in 1926.

Huggins:

I published quite a lot in 1922, but not on rheological subjects.

Knox:

Yes. Well, this wasn't either. This was on structure. I have it here.

Huggins:

Well, that is probably not what you are interested in now, work on structure.

Knox:

No.

Huggins:

I did a lot, published a lot of papers in those days.

Knox:

What I wanted to ask you about, though, because that was the field you were working on then, was at what stage in time did your work on structures or your interest in general research in the work that was going on, lead you to work on structure solutions, and your theories of rubber elasticity that you came out with?

Huggins:

Well, I can talk about that, because I know about that, of course.

Knox:

Right.

Huggins:

I had very little interest in the field of rheology, until I began actually studying the structures and physical properties of linear high polymers in the 1930's. This was after I had gone to the Kodak Co. in Rochester. Then at that time, I learned about Staudinger’s work and his determination (?) of molecular weights of such polymers, using an assumed proportionality between the average molecular weight and the specific viscosity of the solution. Staudinger showed that measurements on solutions of some chain molecules of relatively low molecular weight agreed with this proportionality relation. He also claimed that this was a reasonable relation, considering the fact, what he considered as a fact, that the molecules were rod-like. Then, after that, the fine Swiss physical chemist Werner Kuhn... he developed and published a theory for the solution viscosity of molecules composed of segments arranged in a rod-like fashion. He showed that in a solution with a velocity gradient such molecules would rotate continuously, the rate of motion being relatively slow when the rods were approximately parallel to the direction of the velocity gradient. This theory led to the viscosity dependence on molecular weight, in disagreement with Staudinger’s rule. I later showed that Kuhn's theory led to the conclusion that the rate of motion of solvent past one segment of the rod decreased by the present – I’m afraid I made a mistake here. I was trying to read some crude notes. I must read them more carefully.

Knox:

Well, that's my (crosstalk) — (???) again all right.

Huggins:

If one assumes that the rate of motion of a solvent past one segment of the molecular rod is not decreased by the presence of other segments in the vicinity, then Kuhn's result leads to the conclusion that what we now call the intrinsic viscosity of the solution is proportional to the square of the molecular weight, not to the molecular weight to the first power. In 1922, I had concluded that the molecules of normal alkanes and similar chain molecules, in the liquids and [...] liquid solution, are not rod-like, but are kinked in a very random manner. I thus disagreed with Staudinger’s assumption of rod-like molecules — a theoretical treatment of the Viscosity behavior of highly kinked molecules, was obviously needed. Following Kuhn's procedures quite closely, I made such a treatment — assuming perfectly random kinking, I arrived at the result, again with free draining of the solvent past the molecule, through the molecule, was equivalent to Staudinger's rule. I deduced Staudinger’s rule, not for rods, but for randomly kinked chain molecules, provided the molecular weight was low enough so that free draining was a good approximation. As Kuhn had deduced for rod-like molecules, each molecule — according to my theory — rotated continuously, with a rate of rotation lowest when the molecules are oriented parallel to the direction of flow of the solution. As the molecular weight and so the chain length of solute molecules increases, the assumption of free draining no longer holds, of course, and the intrinsic viscosity becomes less than that calculated by Staudinger's relation. Later experiments have shown that the empirical Mark-Houwink relation, proportionality to the molecular weight to a fractional power, is usually approximately obeyed. My theory also indicated that the velocity gradient in the solution of flexible kink molecules would tend to extend these molecules, making them more nearly rod-like, while they are oriented with their major axes approximately parallel to the velocity gradient. The forces tending to orient and extend the molecules will increase as the molecular weight increases. When I learned more recently, much more recently, about [Albert J.] Pennings' experiments in the Netherlands [e.g. A. J. Pennings and A.M. Kiel, Colloid Polym. Sci., 205(2), 160, 1965], showing the fractionation of chain molecules when a nearly saturated solution is stirred, I explained his results in this way. Recent researches by [Andrew] Keller and co-workers about which we have heard here at this conference [Gordon Research Conference, Polymers] yesterday confirmed this concept. My solution viscosity theory led directly to an equation for the concentration dependence of the specific viscosity that has been widely used. A constant and a theoretical relation — frequently called the Huggins Constant — is characteristic of the polymer, the polymeric solutes, the solvent and the temperature. I might comment briefly on some other theoretical relations deduced by Debye and by Flory for solutions of chain molecules. These use as a parameter the size, for example the radius, of a hypothetical equivalent spherical solute molecule which would contribute to the viscosity, the same as the actual average chain molecule. The equations deduced from their relations have been useful. But on the other hand, I believe that they have led to some confusion in people's minds, with regard to the actual reason for the high viscosity of the chain molecule solutions. These viscosities are dependent on the departures of the molecular shape from sphericity, not on the size of the spheres. Because they are not spheres.

Knox:

Now, when you did this work — this was in the early, mid and late thirties; it covered, as I recall, a few years in time — theory of solution (crosstalk)

Huggins:

— beginning of the 1940's.

Knox:

Right. But this, your theory of solutions, was actually published in several parts. One was the strictly treatment of the Kuhn theory and early stages, and the applications of some of the molecules, and then you also had one portion of it that was the concentration dependence and another portion that was the temperature dependence of the viscosity, and these all sort of followed out of the early work that you did, which was an extension of Kuhn's theory of rods to the kink molecule, as best I can follow it. At the time that you started extending this, and showed that for kink molecules, that this did work well, with respect to Staudinger's original equation, what was the general acceptance of this? Was there at that time a general lack of knowledge, and an interest in anything that was proposed? Or was this suggestion of a kinked molecule rather than rod-like sort of taken with a jaundiced viewpoint? What was the general feeling at that time? The idea of a kinked molecule that had segments that operated, rather than the individual atomic approach?

Huggins:

I think the biggest factor in the general feeling about this thing was the development of the theory of rubber-like elasticity. Very soon, in the early 1930's, soon after [K.H.] Meyer and [H.F.] Mark and [W.] Kuhn and a few others tried to treat rubber elasticity as an entropy phenomenon in a semi-quantitative way, then people realized that these were kinked molecules, and they were not rod-like. At that same time I, and I’m sure other people, realized the necessity for dealing with solutions, with the thermodynamic properties of solutions, and the viscosities of solutions, in a quantitative or semi-quantitative way, so that experiments could be compared with theory on the basis of, what we who were working in that field then believed: Kinked molecules, rather than rods. I showed, first I believe, that the kinked molecules idea led to a reasonable explanation for the thermodynamic property behavior of polymers of chain molecule solutions. [P.J.] Flory followed me with what amounts to the same theory [Flory-Huggins polymer solution theory], so that was taken care of and when I had developed the viscosity theory of solutions, I do not know how many people accepted that immediately, but if they had already been convinced that the molecules were kinked molecules and not rods, that was sufficient. It's just a matter of getting agreement with experiments and determining from experiments what you wanted to know, if possible.

Knox:

At about the same time, you wrote several papers on a new approach to the theory of rubber elasticity, as I recall. I'm trying to figure out the best way to put this, but from what you have said, I gather that you didn't really feel that a treatment of rubber elasticity was really a different approach than treatment of solution viscosity; that in both cases, you were concerned with conformations of the molecule, and the response of the molecule as a result of its conformation to an applied stress, whether it be in solution or in the solid state. Is that a fair?

Huggins:

Oh yes. That is fair. It was shown very early, I guess probably first by Meyer, or by Kuhn, Mark is in there very early; it was shown that the phenomenon of rubber elasticity was essentially one that was based on entropy rather than energy and the arguments for that; the evidence for that is conclusive. So then, there was no argument about the fact that the molecules were kinked. Various people much more competent than I in the statistics and background knowledge of rubber elasticity, or any kind of elasticity, worked on this problem, and they got very important results. There were some details that they argued about, but what I didn't like was that I could not very directly relate their equations to what I wanted to know: to the chemistry of the molecules, to the shape of the molecules, and to the energies and entropies that were involved in changing those — the entropy and energy changes that occurred when the shapes of the molecules were changed. I wanted to tie in the physical theory with chemical structure and energy that changes with molecule shapes and my little contribution was the first step toward that. It was not a very good job that I did, I'm sure, and I knew it at that time, but it was a different point of view.

Knox:

And a very important point of view, as it turned out, from an historical approach to the thing.

Huggins:

I didn't know whether it was appropriate to talk about this rubber elasticity —

Knox:

Oh yes.

Huggins:

— or not. But the viscosity, solution viscosity work I knew you'd be interested in. I have also thought a great deal about viscoelasticity. I've never gotten down to the development of a better theory, along the lines that I wanted to do, as an extension of my early rubber elasticity paper. I've thought about it, and I've talked and lectured about various aspects of these things a little bit, and a book I have written about the plastics role and such things, other than in solution. But these are minor things.

Knox:

Well, I think that there is something — that those of us who are, if you will, current day rheologists tend to forget, and I know that it’s only in my looking back into history that I have realized this — it’s that when the term “rheology” was coined by [Eugene C.] Bingham and [Marcus] Reiner, in their discussions with one another, that as a matter of fact, they weren't thinking — in the first place, they weren't thinking polymers, when they thought up the term rheology. It only happens that polymers were becoming well known and beginning to be researched at that time.

Huggins:

In the thirties.

Knox:

That is right. But only more recently I think that people have tended to think of rheology and polymers as being somewhat synonymous. And that was not the original idea when the word rheology was coined, that it was something which was needed to study these new polymeric materials. The other thing which I think that we current day rheologists many times forget is that the word rheology was not coined specifically to refer to either liquid or solution type behavior, either, but to deformation and flow of materials, regardless of the material and regardless of whether it was solid or liquid.

Huggins:

Certainly.

Knox:

So that theories of elasticity, deformation mechanics, all of these things which have to do with solids are very much an integral part of rheology. They’re very much a part of the history of rheology, and they're very much an essential part of the history of the Society of Rheology, because our earliest papers and our earliest works had much more to do with plasticity and with stress/strain behavior and rubber elasticity and elastic behavior than they did actually with fluid flow. And it is I suspect typical of all people that one tends to think that the field that he is working in is the most important. And that's good, we should feel that way, that what we're doing is the most important thing that could be done. But I think it's very easy to neglect and to overlook work that's done in other areas that equally falls under the definition of rheology, and this is why I was so much interested in the work that you did on the theory of rubber elasticity in the early stages of the game. Because rubber elasticity — rubber has been around for a long time before we knew what a polymer was. We worked with rubber before we really understood what it was. We — it was only after we learned about long chain compounds and that, about chemical reactions that could occur with long chain compounds, that I think we began to really understand how rubber behaved. It was very phenomenological, if that's the right word, in the early stages, of the game, rather than the theoretical. And I think that probably, at least in my opinion, the fact that you, you might say, entered the field of rheology because of your interest in the structure of matter, regardless of whether it was polymeric matter or atomic materials, may have helped a great deal in looking at it from a structural standpoint, rather than from a mechanics standpoint or a phenomenological standpoint, of, “Let’s explain what has happened.” And I think your approach was, "Let’s explain what we have, from a structure standpoint, and see if we can relate that to the way it behaves,” rather than looking at the behavior and working back to say what structure can possibly explain what we observe. Would you agree that that is in part the way that you have approached it looking at the structure of the material?

Huggins:

Yes. It might be pertinent to mention a little bit of the history of my interest in this field.

Knox:

I think that would be very pertinent.

Huggins:

When I went to Eastman Kodak Co. I was given two jobs. One, to be in charge of the X-ray diffraction work, later expanded to electron [diffraction]... [another] was to take an interest and help wherever I could, in the work on polymers, at that time usually called synthetic resins, at the Eastman Kodak Co. I was working under Professor Shepherd. I'm sorry he was not Dr. [S.E.] Sheppard. He was assistant director of the Kodak Research Laboratory, and in direct charge of chemical research. He had done quite a bit of research, and I guess it was good research, on properties of gelatin, which of course was important to Kodak. And he had published quite a number of things in that field. He had been active, I believe, in the early days of the Society of Rheology. I don't know much about that activity, but he was interested in rheology and in that Society, and he encouraged me to go to its meetings, where we discussed the work that he and his associates had done and were doing, chiefly on gelatin. He was also interested, of course, in what I was doing in connection with the structure and properties of polymers, — rubber elasticity, viscosity, solution thermodynamics, structure especially, related to gelatin, polypeptides, natural polypeptides, and so forth. Well, he encouraged me to work on these things and to present papers at the Society or Rheology meetings. I thought that background was perhaps a little bit pertinent.

Knox:

Yes, it is.

Huggins:

I don’t know, it’s a long story (crosstalk) but at least you will know what it is.

Knox:

I was going to ask you, Dr. [S.E.] Sheppard was one of the founding members of the Society of Rheology, the second president (crosstalk) an early assistant editor, he has been very active. There were a few other people also who were at Kodak, and I’m trying to find their names. I should have it right here. There was also a man, I believe, named Hirsch, whom you may —

Huggins:

— I don't recall Hirsch.

Knox:

Or maybe it was Halk?

Huggins:

Maybe that was before my time.

Knox:

Who worked with Sheppard?

Huggins:

There were people like Musem (?) and Lambert, I remember.

Knox:

I do have the wrong pad… however, it's in here. There is one thing, and I'm probably not keeping this in the proper sequence, but I recall one of your papers in which you pointed out that you needed to be very careful about using a “viscosity average" (in quotes) “Molecular weight.” That this might not be a proper average for describing your polymer this was a paper which I have out here, on Molecular Weights of High Polymers, that recommendation of being a little careful about using this equation that you were instrumental in giving a constant to, as being, if you will, the be all, end all, in describing molecular weights of the polymers.

Huggins:

I became especially involved in different kinds of averages when I was in charge of the first reports on nomenclature for high polymers. And we had this problem or the kinds of average that came out of different kinds of experiment methods. And because of my solution work, I knew that the term “viscosity average” did not make sense, unless one expressed something more – what kind of a solvent it was, the temperature, and if you did not extrapolate to infinite dilution, or if you did extrapolate — things like that. And I was a little worried by the fact that various people were using the term. "Viscosity average” without explaining just what they meant by it.

Knox:

As though it were an absolute number.

Huggins:

Yes. It was not like the other kinds of averages — the weight average and the number average. It was not a definite thing, unless you specify what solvents you're measuring, the viscosity and what temperatures.

Knox:

Was this reasonably well received?

Huggins:

Oh, I guess so. This came out in the reports of my nomenclature commission, and I didn't hear objections.

Knox:

With respect to the Society, I think it was, as you know, THE JOURNAL OF RHEOLOGY was issued only for about three years, '29, ’30 and ’31 [+1932], as an actual journal. Then in 1931, at the same time as the founding of the American Institute of Physics, which he Society of Rheology was one of the founding members, it was decided to take the JOURNAL OF PHYSICS, rename it to the JOURNAL OF APPLIED PHYSICS at that time, and to have Rheology papers published as part of the issues of the JOURNAL OF APPLIED PHYSICS. So at that time, the JOURNAL OF RHEOLOGY was discontinued, and the JOURNAL OF APPLIED PHYSICS had two editors, one from the Physical Society and one from the Society of Rheology. And this continued for several years, and then bit by bit, because of the size of the American Physical Society and the smallness of the Society of Rheology, the number of pages; devoted to Rheology became less and less and it was more or less of a natural trend. But eventually it reached the point that papers on Rheology were not being published on a regular basis in the JOURNAL OF APPLIED PHYSICS. And I believe it was in ’42 that you were asked for your opinions on the formation of a new journal. Professor Mark, I believe, was chairman or president of the Society at that time, and you were one of several people — [T.] Alfrey was one, you were one, who were asked to give your comments, what you felt concerning the formation of a new journal. And I think I’d better — I guess I'm going to have to postpone that for the next time we talk, because I left that in the room. I have a copy of your letter. (crosstalk) I have a copy and we will do that in the very next one. I thought I had it with me, but because of our moving from room to room, I seem to have that in the other stack of material. So I'll have to delay that portion of the discussion, until the —

Huggins:

I know, I have a reference to that letter to the Editor that you're speaking of, probably.

Knox:

Right.

Huggins:

But I don’t have a copy of it.

Knox:

I’d be happy to give you a copy.

Huggins:

I couldn't remember just what it was about.

Knox:

I don’t know whether you happen to remember, in JOURNAL OF APPLIED PHYSICS, the paper that — this was Part 3 of your "Viscosity of Dilute Solutions” [M.L. Huggins, J. Appl. Phys., 10, 700, 1939] in which you were speaking about the Staudinger viscosity, I just wondered if you had seen this recently, and remembered how you looked in the mid-thirties?

Huggins:

Terrible.

Knox:

No, I think, very good, as a matter of fact. It’s not a very good copy but it was…

Huggins:

Well, I know that paper's good.

Knox:

I'm sure you do.

Huggins:

What I can remember of it.

Knox:

Yes, I have it here — it was in 1935 that Sheppard was the President of the Rheology Society. It was shortly after that that I believe that Professor Mark started the Saturday morning meetings at Brooklyn Polytechnic, which lasted for so many years, and as I recall, he had a special session on viscosity in February, for several successive years. I've noticed that you spoke at two of them. You were usually the lead-off speaker in the early forties. The one in '42 was on — as a matter of fact, they said that Eastman Kodak was in Buffalo in their program that particular year. This is a copy of it, on the program of the 1940's, and the theoretical fundaments, as they called it.

Huggins:

Yes, I — that may have been the time I can tell you about at least. About that time I went down to one of those Brooklyn meetings by invitation to give a lecture, and the — of course, they wanted [Herman F.] Mark to introduce me. But they had to introduce Mark. They introduced, let’s see, first the president of the Polytechnic Institute of Brooklyn spoke, and he introduced, I think it was [Raymond E.] Kirk, who was head of physical sciences or some such group as that, and then Kirk Introduced Mark. He had to introduce Mark because Mark was away on trips most of the time and then March introduced me. I thought that was funny but not in print.

Knox:

There’ll be plenty of opportunities for you to –- those original meetings then that Professor Mark set up were actually sponsored by the Society of Rheology?

Huggins:

I wouldn't remember that.

Knox:

It was not just the Polytechnic Institute of Brooklyn.

Huggins:

That was a different meeting from the one I was talking about.

Knox:

Yes. But these were sponsored by the Society of Rheology, but they were still Brooklyn Polytechnic meetings, and I suspect that the introductions did go exactly as you describe. Because it was not too much different from that when I first went, in the very early fifties, which was still significantly after this. But Professor Mark was always introduced before he introduced the speakers, when I went there several years later. There was one other paper that has done pretty well, that you presented at that meeting. Oh yes, this was again part of the Viscosity of Dilute Solutions, and this was the concentration dependency [M.L. Huggins, JACS, 64, 2716, 1942]. It had been at a Society of Rheology meeting at Brooklyn Poly in 1942, and at the American Chemical Society. I think most of the work that you were doing on the solution theory, and also on the theory of rubber elasticity, was done while you were at Kodak, wasn’t it?

Huggins:

Oh yes, all of that.

Knox:

After you left Kodak and came to California, I assume you must not have lost interest, since we certainly have heard from you since you left Kodak, in the field of polymers and solution thermodynamics, but what was the general attitude on the West Coast at that time, concerning this relatively new field, of the properties of high polymers? As I recall, there was only some work going on in the rheological aspect of high polymers on the West Coast, when you came I believe to Stanford at that time.

Huggins:

There was very little work on high polymers. Certain research laboratories, oil companies, Shell and Standard, had some people about that time getting into it; very little in the universities. After I had been at Stanford Research Institute for a while, it appeared that there was a chance that you could get [Paul J.] Flory out in that vicinity and I did what I could to encourage Stanford University to invite him, and Stanford Research Institute to help financially by making him a consultant, and so on. After Flory moved to Stanford [1961], that was really the beginning of any appreciable amount of work on high polymers in that part of California except for what was done at the oil companies. I think that a little before that time, had come to USC, and he was working down there.

Knox:

I’m trying to remember, you went to Stanford — that was when, 1950?

Huggins:

Stanford Research Institute?

Knox:

Yes, that was — well, you were an instructor at Stanford before you went to Eastman Kodak.

Huggins:

Oh, I was an Instructor and then an assistant professor in the twenties, 1925-1932. Then I worked at Johns Hopkins.

Knox:

In your first tour at Stanford University, that was a little before you started working on the solution.

Huggins:

Yes. My experimental work then was all X-ray diffraction work.

Knox:

So that the work that you’ve done in California on polymers was, you might say, your second tour of duty here.

Huggins:

Well, while I was doing this early structure work, I was interested in polymers in the solid state, in the crystalline polymers, and I kept in the back of my mind that interest in polymers, all through the years. When I was at Harvard, just after getting my doctorate, I became very much interested in polymers, not in viscosity or other rheological properties. I have thought a little bit about what I heard about Emil Fischer’s work on polypeptides, and that was interesting. Then while I was at Harvard, I read an article in the JOURNAL OF AMERICAN CHEMICAL SOCIETY by Roger Adams and two of his students [Roger Adams, J.E. Bullock and W.C. Wilson, JACS, 45(2), 521, 1923], in which they reported work on condensation of what we would now call bi-functional molecules. One being, for example, benzidine and the other being terephthalic acid, terphthalaldehyde or something similar, also bi-functional. They reported condensation products which analyzed from one unit or each of these two components, after you take out the H2Os in your condensation reaction. So, they concluded, these are rings. Being rings, then the (???) from the benzidine must have a structure which has a formula such as had been proposed earlier by a man by the name of Kaufler — one ring over the other. That was their conclusion. I didn’t believe that. I looked carefully at their experimental evidence. These products were highly insoluble. They were insoluble in all of the organic solvents that they tried, all of the solvents that they tried, the common solvents. The products would not melt without decomposing. I concluded that that instead of rings, these were some kind of polymer (?). To myself and in my notes, I had to call them by a name. I called them "string molecules.” So I was very much interested on that. I wanted to check up on that. I thought, “If I am right about this, then there must be many other examples of condensation in the literature, leading to products which are supposed to be rings, but which are not rings.” I looked through the volumes that then were the Beilstein [Handbook] for certain products, research products of that kind, from bi-functional starting material, and I found many of them, reported as rings, but all having these peculiar properties — being entirely or almost entirely insoluble, and decomposing when you tried to melt them. I, at that time, was all prepared to move from Harvard, where I was working in an organic chemistry laboratory, to Cal Tech, because I felt that the problems that I was most interested in could be solved better by X-ray diffraction than by –- by me as an organic chemist, because I had almost no training in laboratory organic chemistry work. I should have talked about these string molecules with Professor [Elmer P.] Kohler under whom I was supposed to be working. But I did not. I was afraid he would want me to stay at Harvard, to do experimental work on this, and I knew I wasn't a good organic chemist, and I wanted to go to Cal Tech. So I did not even mention this to Kohler. I still retained an interest in string molecules, and a number of years later, when I wanted to go from Stanford University to a meeting in the Middle West, I did not have any experimental work ready to report, to justify the trip. I decided to report the story about these molecules, and I did. At this meeting where I reported it, there was a discussion afterwards. Somebody said to me, “There is a man at DuPont named [Wallace H.] Carothers who seems to be making the kinds of molecules you are talking about.” And somebody else mentioned a German who had also been making such molecules, string molecules as I called them. And I cannot now remember the name, but I'm sure it must have been (???) (Faber?).

Knox:

Yes, I'm sure it was.

Huggins:

So again, my interest was aroused, to work on the problem, and the problem was, properties of chain polymers, special. But I did not actively get into the experimental work in that field, or further theoretical work, until I went to Kodak in 1936.

Knox:

Did you know when you came back out to Stanford in the late fifties that —'58?

Huggins:

It was January '59 [through 1966].

Knox:

Right. Dr. Bondi, Arnold Bondi, I believe was with Shell all that time — Arnold.

Huggins:

Oh yes, Arnold. I knew some of his work.

Knox:

He had been very active earlier than that in rheological work. I think probably was one of the people on the West Coast who pushed very hard for work on polymers and polymer rheology, to be connected on the West coast —

Huggins:

— I do not think I met him before.

Knox:

I see but later —

Huggins:

I met him later.

Knox:

There was one other thing which, for the record of the tape which is being made, has very little to do with rheology but which I found very interesting, and I don’t remember the date now but I think it was in the early forties, the — based on X-ray diffraction repeat distance, in material such as polyvinyl chloride versus polyvinylidene chloride versus polyethylene, you first proposed what today would be called a “syndiotactic polymer,” and because of the repeat distance, there was no way to explain the repeat distance in polyvinyl chloride, except by an alternate location of the chlorine, on opposite sides of the chain, as it went down. This was the only reasonable explanation for the X-ray diffraction pattern.

Huggins:

I was much interested at that time in the principles of crystal structure of polymers, in the case of polymers which did have a crystal structure. In the early days, when most of the synthetic polymers were vinyl polymers, then there was no crystallinity dimension, and one could not get X-ray diffraction data that could be interpreted in terms of the structure. But for the few cases where there was crystallinity, I found some rules — that in order to agree with some of the basic principles of crystal structure, I deduced, for example, that if a linear polymer could not form a stable regular zigzag structure, it would necessarily form a helix. And that was the beginning of the helix idea — I used that a great deal in studying polypeptide structures. Another principle of course was that if hydrogen bonds can be formed, from the group which are present, they will be formed, and to a maximum extent. In general, every pair of hydrogen [...] found in the group will form a hydrogen bond. And in a regular crystal structure, you can assume that that will be true. There was much experimental work by that time showing that this principle was right.

Knox:

Yes.

Huggins:

But people have not applied it to polymers.

Knox:

The reason I was interested was that, as you recall, during some of the recent litigation on polypropylene, there were questions raised about “When did one first think about isotactic or syndiotactic regularity in the chemical structure which leads to crystallinity? Was [Giulio] Natta the first person who ever suggested this?” And it was obvious rather quickly that regularity in the arrangement of asymmetrical (carbons?) had been suggested many many years before — not in the same terms, that isotactic or syndiotactic. Those were terms that he coined. But certainly the concept of a regular arrangement, either all on one side or alternating sides, was well recognized by the people who were working on structure of polymers for many years before we knew about isotactic materials or syndiotactic materials. And I hadn't realized until reading through some of this that you had been involved in that work also.

Huggins:

Perhaps you are familiar with the literature I published, oh I don't know, perhaps 1945, about this problem. If not, I’ll say something about it.

Knox:

Fine, I'm not sure that I have this.