contemporary hi~tory
LEONARD editedFINE by: Columbia University New York. NY 10027 ERIC
S. PROSKAUER
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Polymer Chemistry in Europe and America-How
it all
Herman Mark Polytechnic Institute of New York, Brooklyn. NY 11201
I finished my university studies in Vienna, and in the summer of 1921, moved to Berlin with my teacher, Wilhelm Schlenk. He was a very progressive organic chemist and studied trirolent carbon for years with great success. We now refer to such reactive species as stabilized free radicals. When I did my thesis on the same general subject matter 1 got in rather close contact with Schlenk professionally and personally. He was an extremely fascinating teacher a t all levels from freshman to graduate. 1 remember that wenamely the group of his closer collahnrators-did not see him the whole day, while he was busy taking care of all kind of matters such as lectures, examinations. conferences at the I n l w r s t \ , t h t . :I(.:II~cIII\, t h e h l ~ n ~ s t r y E d t ~ c i ~ t i and w ~ , the \ l i t > i s ~ r v. t i t ' ~ n a m v Hut ~ . twervdav . . in t l i e e v e n i n g a t ' t e r d ~ t ~ . ner, he came over from his apartment, which was a t the Institute to chat with us ahout our work and the progress which. we had-hopefully-made. He would go to each laboratory hench. checking on our materials and instruments, asking questions and giving advice. Professor Schlenk would not hesitate to carry out an entire elemental analysis with his own hands right before our eyes. Then, smoking a cigar, he would sit on a lahoratory stool and tell us stories about Willstaetter, Rayer, Fischer, and Windaus and draw our attention to important recent events in chemistry. My preferred subject was physical chemistry and so I was particularly interested in the seminars and lectures of R. Wegscheider, E. Ahel, and K. F. Herzfeld. My doctoral dissentation was in organic chemistry o n the synthesis of Pmlaphrnyluthyl, a new compound containing trivalent carhon. As assistant to Schlenk in Berlin, who was
In what can only be described as a rare opportunity for the readership of the JOURNAL OF CHEMICALEDUCATION,two scions of the house of science have each provided warm, personal statements about an emerging giant. polymer chemistry. Herman Mark and Carl Mawel were eyewitness participants from the birth of the macromolecular concept in the early 1920's and, at a time in their lives when most of the rest of us would be pleased to find ourselves in a rocking chair at the ''old chemists' home." they are alive and well, staying young by still practicing their an. The circumstances of these two documents are quite different. Herman Mark's reflections and recollections were taken from recorded conversations with Professor Dr. D. 0. Hummei of me University of Cologne. Baurat h.c Dr. H. Tscharnler in Vienna prepared the German text, and the English translation was provided by Dr. Eric Proskauer in New York Carl Marvel addressed an assembly of chemists at the Houston Meeting of the American Chemical Society. He has provided Me manuscrbt of his eresentation, We editas (Roa*auw and Finel have vied to maintain Me style of the aigiml statemems in % hope of leaving the reader with something closer to the essence of these two men and their first steps on a virgin landscape.
the successor to Emil Fischer, I continued working in the field of "Free Radicals." But one day, Fritz Haber who was a good friend of Schlenk, visited him and told him: "You know, we are starting a new "Kaiser Wilhelm Institute ofFiher Chemistry" and for it we need good people. I have quite a number of able . ~hvsicdl chemists but we need somehudy who under" stands something of organic chemistry. You see, after all, cellulose, silk, and wool are organic substances." Schlenk called me and, in acigarsmoke-filled room where the two ~rofessorswere sitting, asked me whether I would ioin the &Fiber Institute as a-scientific assistant. I answered that I would not like to be separated from him and his Institute, hut if he did not ohject I would like to try the new position for a year or so. Therefore, the agreement was made that I would move at the beginning of 1922 tu Berlin-Dahlem where the new Fiber Institute was located. The head of this Institute was R. 0. Herzoe, who was always full of good thoughts, especially the idea that one might appiy the newlv discovered X-rav diffraction methods svstematiand P. Dehye and P. Schkrrer in Gbttingen had made s&ne X-ray of fibers and found a few diffuse spots or rings. . pictures . But these were only preliminary, scouting experiments; Herzog intended more. He wanted to devote one whole part of his institute to this prngram. I t was a very wise and fkrreaching decision. The first step was to huild a modern X-ray apparatus with an efficient, durable X-ray tube. Such tubes were not commercially available a t that time, but had to he individually
Herman F. Mark was born in Vienna. Austria. in 1895 and received his PhD from the University there in 1921 after serving for almost four years in the German Army during World War I. He worked for the Fiber Research institute in Berlin-Dahlsm until 1927 when he went to the research iabaataies of I. G. F a b n in LwJwigshafenon Rhine. At Me Fiber Research Institute he began studies which led to the elucidation of the Shuctures of cellulose, silk. rubber, chitin. and starch and, subsaquently. to the investigationat synthetic polymers at I. G. Farben. Political conditions in Germany caused Mark to first accept a posrtion at Me University of Vienna in 1932 and Men to leave for Canada in 1938 when Hitler invaded Austria. After two years as research manager for % International Paper Company in Hawkesbury.Canada. heand his family moved tome United Sfates. he loinad the staff of the Polytechnic Instituteof Brwklyn where he was instrumentalin foundino the Poivmer Research Institute . in 1946. Professor Mark's many contributions to the field of polymer chemishy have earned him many awards and honorary degrees, among them election to % National Academy of Scienqes in 1963 and the 1979 National Medal of Science
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Volume58
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527
built out of glass and metal in the workshop. and made airtight with Picein and a numher of other sealan-. Herzog selected two people for this joh-a graduate student, Rudolf Rrill. and me. Since Herme's lnstitute was not comoletelv finished a t this time, we were quartered in the hasement of Prnfessor Haher's villa. Dir ( k h r i m r a t himself was quite indifferent about this. Mrs. Haber, of course, was less indifferent, hut the greatest objection came from the Hahers' dog "Schnautzl." He didn't like the intrusion of strangers through the garden into the cellar a t all, and harked loud and continuously. Soon, hnwever. Hrill and I succeeded in appeasing him with some sausage ends. After that, he only wagged his tail to meet us when we came in. " We started simultaneously tu construct two different types of X-rav tubes: in case one would not work. we would have one in reserve. Naturally, both tuhes failed to function a t first, but after some weeks we oroeressed far enough so that we could make diffraction experiments with X-rays. If we had started immediately to investigate cellulose. silk or rubber, we would have had a very hard path ahead of us hecause of the comwlexitv of these suhstances. We began instead with the determination of such simple structur& as zinc and tin, and with the deformation mechanism of these metals which had been studied intensely at this time hy M. Polanyi, E. Schmid, and K. Weissenberg. In the years from 1922 tn 1924 a systematic investigation of these metals was carried out, and we learned a great deal how to work in the field of X-ray structure analysis. We came to the conclusion that we would next study organic suhstances, the quantitative structure of which was not yet known at the time. These were not yet polymers hut still simple crystalline organic suhstances like urea, urotropin. carbon tetrabromide, and others. Then we started t n investigate simple condensed gases such as ammonia, carbon dioxide, boron hydride, and ethane in the solid crystalline state. This work required the use of very low temperatures which we achieved with the help of E. Kuss and K. Pohland a t the lnstitute of Professor Stock. We had, for this work, to combine X-ray diffract.ion techniques with the use of cryogenic conditions which was a t that time still a difficult experimental art. Rut we were lucky, and Rrill was a very skilled experimentalist. Even though inflation caused a lot of excitement in these years. Haher, Hahn, and Reckman had a t their disposal relativelv laree funds from a .laoanese Foundation. orovidina us with Bd~q;;atewpport. ~dditilmolmoney came i r m se&l foundatitms in thr IISA. With dollarsand ven evervthine was available a t that time in Germany. 1 likito men& chat I ~
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The younq Herman Mark. Vrenna 1907
528
Journal of Chemical Education
continued to make structure investigations on organic suhstances even much later during my acl.ivity in Rnmklyn. If one isexperienced and well trained in a certain field, why should one ahandon it if one sees sr,n)e new ancl interesting application of it. I'rnfessar 1. Fankuchen investigated (in Brooklyn) cyclnwtatetraene, a very interesting suhstanre W. Reppe had prnduced in p x ~yield. l Cyclnnctate~raeneis a liquid a t normal temperatures and since we were practiced in the crystallization nf liquids and in the determinatinn of the structure of the fine powders, we had a 101 of fun with this investigation. At that time there were several prtqs~salsfor the structure of cyclooctatetraene. If the molecule is an R-memhered ring, it can appear in the hnat form, and chair fnrm. or the crown form. If all douhle honds are "trans" it has the crown fnrm; when two douhle hands are "cis" and two douhle honds are "trans," then it has the chair form; and i f all are "cis" it has the boat fnrm. We k~undthat cvclrrwtntetrnene has the crown form. In thesummer of1922,I went 111Vienna fur several weeks, married Mimi Schramek. and came hack after our honeymcmn with her 11)take up residence in our flat in Rerlin an Lichterfelde-West. In the following years we became very well equipped in the X-ray laboratnry of the Filwrs lnstitute hecause our X-ray apparatus was. a t that time, prchahly one ol'the hest which was available in the world. Hence, we started to work also in the field of the physics of X-rays. Several papers were puhlished jointly with P. P. Ewald. W. Ehrenberg. H. Kallmann. and I. Szilard, one nn the an(,malous dispersion and the polarization of X-rays. We knew we had a powerful scientific tool, and we knew enough to use it wherever ancl also to study the fundamental characteristics of this tool. One day in 1923. Alhert Einstein came to the lnstitute and excitedly related huw an American, Arthur H. Compton (in St. I,ouis), had puhlished an experiment which wnuld prove without douht Einstein's own light quantum theory. Other important physicists in America and England, however, had not heen ahle to confirm Comptnn's experiment which would, of course, speak against the light quantum theory. Since the Compton Effect is a phenomenon of X-ray scattering, Einstein asked me if we could try to repeat the Compton experiment. We all agreed, of course, and after a few months, Kallmann and I were able to make some very good, clear photographic patterns of the Compton Effect. Einstein was naturally very pleased that this possible opposition tn his theory had been experimentally eliminated. In these davs. I was asked hv G. Hredig in Karlsruhe to write a bunk abnut the application of X-rays in chemistry and engineering. I agreed. of course, and the honk was puhlished in 1926 hy dohann Amhrosius Barth in Leipzig. It discussed the question of the productinn of X-rays, their measurement, and application. Finally, we presented as examples 3 or 4 crystal structures which we had determinated at that time. I do not know how large the edition of this book was, but it was nut of print after 10 years. F. Halla and I published a second edition in Viennaahout ten years later, which was highly condensed and contained, more or less. only recipes with almost no text. I t was a very practical huok. One day in the summer of 192fi. Grhrimrat Haher asked me to visit him. He said. "Dear Mark. Tomorrow I expect a visit from a good friend of mine, K. H. Mever of I.G. Farhen, Ludwigshafen." The I.(;. wns now occupying itself very strongly with fihew. The plants which prepared nitrocellulose during the war were now heing activated again, not for dynamite but for other derivatives of cellulose like cellulose acetate and xanthate. From these raw materials one was ahle to make very useful films and fihers.. .cellophane,and rayon. "You, dear Mark, have worked with Herzog rm the structure of cellulose, silk and ruhher, and on the influence of orientation upon strength and elasticity and have written several papers about it. The management of the I.G. Farhen and particuarly
Professor Meyer are very much interested in this area and would like to talk with you about it." The next day, Professor Meyer arrived and told me that the LG. had decided to build a new laboratory in which such problems should he studied systematically, not only with cellulose but also with their other fibers. Unfortunately, he thought these fibers were presently of very poor quality and could not be laundered without damage. At this point, I might mention that a t the time of our discussion there existed five larre research lahrnatories at 1.G. Farben. One of them was for inorganic chemistry at Bitterfeld. Its manager was L. Pistor. The second was at Leverkusen, mainly fo; dyestuffs and pharmaceuticals, under the leadership of C. Duisherg. Then there existed the large researrh laboratory a t Hoechst for dyestuffs, pharmaceuticals, and intermediates with E. Schmidt as manager, and finally there were two laboratories in Ludwigshafen, one in Oppau, the ammonia laboratory for fertilizers managed by A. Mittasch, and the main lahoratorv in Ludwieshafen under the directorship of K. H. Meyer. kt this t i m i i t had heen decided that the laboratorv a t 1,udwiashafen should concentrate on svnthetic fibers a i d films. t hat meant on high polymers, a t k m that did not exist a t that time. What was clear was that this laboratory should deal with synthetic substitutes of natural fibers and films. For this reason a new laboratorv was heina built and I should become its manager. The pn,spect soundpa very a t t r a c t i ~and ~ intriguing. and thereiore. day. wirh my rife. Mimi [we did not hnrr children yet I. I travrlled Irlm Rerlin to Mannheim, alld we were put U P rcwlls i n Heldel. berg-the I.G. did not spare any costs to tempt and please us. Professor Meyer and 1 walked through the laboratory and the plant. We talked a lot with Mittasch, 0. Seidl. and other directors. On this occasion I explained my ideas ahout my fut.ure function. I told them that it was mv. snecialitv in accordance . with my education not 10 work un manufart&ing o r produc101 the inlluence oistructure uoim tion hut tm the investiaat~~m technical properties kke strength and elasticity, softening point, water retention. and others. We had already investigated hemp, cotton and silk, and some rayons hut the scope now should be extended. One would have to take samples from the spinnerette on separate occasions and try to findnut what h a.o.~ e n e dduring the soinnina.. . pnxess. One would be ahle to do this very well with the necessary instruments, apparatus and . people, especially physicists and physical chemists, and . .. of course, a few good organic chemists. Meyer was in agreement with such a program and he had already lined up a very good organic chemist, a pupil of R. Willstaetter (in Munich) named H. Hopff. After Meyer and I had exchanged our professional ideas, and found mutual appnwal, he took the first step and invited his wife and my wife ~ I aI wine juurney in Iherkheim to celebrate our beeinnine.. coooeration. We were . already in very good spirits. At this time we started a friendship which lasted all our lives. not unlv for the men, hut for the women, too. As a result of this visit, I moved from Herlin to Ludwigshafen in January 1927. We hired a numher of very ahle young scientists, among them, J . Hengstenberg from Freiburg. I
