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Kargin lectures
Kargin lectures
3235
firmed that the strength of C--S bonds of poly~ner I I is higher, the stability of polysulphone-arylates to the effect of temperature being determined by the heat resistance of ester bonds.
Tra~slated by E. SEMERE REFERENCES
1. C. T. HODGES and R. S. MATTSON, Analyt. Chem. 37: 1065, 1965 2. A. I. SIDNEV, Yu. V. KHVASHCHEVSKAYA and I. A. ZUBKOV, Pla~t. massy, No. 6, 61, 1968 3. A. A. KUL'KOV, Dissertation, 1973 4. I. V. ZHURAVLEVA, Dissertation, 1965 5. L. I. DANILINA, E. N. TELESHOV and A. N. PRAVEDNIKOV, Vysokomol. soyed. A16: 581, 1974 (Translated in Polymer Sci. U.S.S.R. 16: 3, 672, 1974)
REPORTS KARGIN LECTURES* P. V. KozLov THE Kargin lectures were held m the Chemical Faculty of the Moscow State University on 23rd J a n u a r y 1975, the fifth series since their inception (1971). This particular type of contact between a wide circle of specialists in the field of polymers is becoming a tradition of Soviet polymer science in respect for the memory of Academician V. A. Kargin, the eminent scientist of our country. The fifth Kargin Lectures were opened by V. A. Kabanov, President of the morning session, Corr. Member of the U.S.S.R. Academy of Sciences, who described to the audience the thematic trend of these lectures and threw light on some aspects of V. A. Kargin's scientific activity. As in previous lectures, the first paper read by A. B. Zezin was of a memorial nature a n d briefly reviewed V. A. Kargin's work in the field of polymer electrolytes. I n the course of his entire scientific activity in the field of polymers V. A. Kargin gave particular att e n t i o n to the study of polymer elctrolytes. V. A. Kargin's interest in polyeleetrolytes was due to the fact that these polymers are very sensitive to changes of surrounding atmosphere which result in various structural formations. Using experimental results concerning the structural morphology of polymer electrolytes in solution V. A. Kargin formulated basic theories concerning the structure of amorphous polymers and types of primary supermolecular formation in them. The lecturer was concerned with details of V. A. Kargin's studies both of structure formation of irregular and regular polyolectrolytes and the link between these processes and similar effects in biological systems. Investigations by V. A. Kargin concerning the structure of polyelectrolyto complexes as models of complex biological systems and polymerization of ionogen monomers on polyelectrolyte matrices, which had been started under the direct guidance of V. A. Kargin, form this part of the studies. The lecturer subsequently dealt with V. A. Kargin's investigations of the simulation * Vysokomol. soyed. A17- No. 12, 2815--2818, 1975.
3236
P . V . KozLov
of functioning of biological systems which, in particular, resulted in formation of macromolecular catalysts. The principle of activity of these catalysts is similar to that of fermentation. The lecturer also d(~alt with V. A. Kargin's work in developing ion exchange polymers and macromolecular complex('s, examining processes of stabilization of suspensions and soils using polymer electrolytes, studying properties and structure of some albumens and mainly gelatin and finally, the use of polyelectrolytes for medicinal purposes. Finally, the lecturer briefly described V. A. Kargin's views concerning means of developing views about polymer electrolytes, the strategy of scientific research in this field, compared with the field of conventional polymers, the large scale production of which has now reached significant proportions all over the world. The morning session of the Kargin lectures was also concerned with three further papers in the field of polymer synthesis, structure and'mechanical properties. The first of these papers was read by Prof. A. N. Pravednikov about the synthesis of polyhetero-arylenes by ring formation using isomerization. Studies were reviewed which were mainly carried out under laboratory conditions by isomerization synthesis of heat-resistant polymers. Methods of synthesis were examined of new m o n o m e r s - - a r o m a t i c bis(o-aminonitriles) and bis-(o-chloroformylnitriles) and polyheteroarylenes prepared from them without the separation of volatile products at the stage of ring formation. A description was given of the structure and properties of several new polymers obtained by ring formation using isomerization: polyiminoimides, polyquinazolones, polyiminoquinazolones, polyquinazoline diones, polyiminoquinazoline pyrrolones, etc. Special attention was paid to the synthesis of heat-resistant polymers without liberation of volatile products both at the stage of pre-polymer formation and at the stage of ring formation. The advantages were indicated of synthesizing heat-resistant polymers by isomerization, compared with well-known two-stage methods. Acad. Kh. U. Usmanov, of the Uzb. S.S.R. Academy of Sciences then described the success achieved on the field of structural investigations of cellulose and cellulose derivatives. He emphasized that investigation of the supermolecular structure of cellulose and cellulose derivatives over several years in Uzbekistan provided convincing evidence supporting V. A. Kargin's theories about the structural dependence of properties of polymers. Cellulose which is a rigid chain polymer with a fairly regular chain structure and intensive molecular interaction, is characterized by a tendency to form various kinds of molecular ordering both in the course of biosynthesis and during precipitation from solutions. As a result of biosynthesis primary elements of supermolecular organization--microfibrils are formed, the transverse dimension of which is 60-80 A. Micro fibrils are characterized by the formation of thin sub-layers or lamellae which form the main mass of oriented cellulose fibres, a secondary wall. A similar structure combined with high molecular weight ensures high strength and modulus of cellulose fibres with retention of physical and mechanical properties in the wet state. F r o m an analysis of literature results and electron microscope studies when forming models and systems of the structure of cellulose fibres, the author proposes to adopt the following principles: natural cellulose macromolecules no doubt have straightened conformation; for cellulose hydrate fibres chain particles m ay exist in a folded conformation. Microfibrils have a heterogeneous structure with statistical alternation of large and small regions. The dimensions of these ranges m a y differ considerably according to the type of cellulose preparation. By forming fibres under mild conditions highly oriented elongation m ay be achieved which results in a structural change-over of fibrillar elements, accompanied by a noticeable increase in the length of ordered sections. This principle forms the basis of new types of cellulose hydrate fibres, e.g. "polynose" fibres. A h i g h orientation of microfibrils and paral-
Kargin lectures
3237
lel chain arrangement in structural elements ensure considerable fibre strength, but reduce breaking elongation and stability to repeated deformation. At the same time, changing conditions of precipitation and orientation elongation a structure m a y be formed which in m a n y ways is similar to the structure of high strength natural fibres. The same correlation between structure and properties was found in erosslinked, cyanethylated graft and a c t i v at ed cellulose. Results convincingly confirm the relation between supermolecular structure and properties of cellulose materials and the considerable possibilities offered by electron microscope methods of studying polymers. These have been extensively developed in this country and are due ~o V. A. Kargin who showed considerable interest and constant at t en t i o n in this field of poly~ner science. Finally, 8 paper was read at the morning session by S. A. Arzhakov concerning the structural and mechanical behaviour of polymer glass. A study of reduction of polymer glass samples subjected to forced elastic deformation shows that forced elastic deformation generally comprises two components. One relaxes at temperatures lower than the glass temperature, and the other in the glass transition range. The ratio between the low and high temperature components of forced elastic deformation and subsequent relaxation is determined by the overall degree of deformation and the temperature of deformation. This is used to explain some features of the conversion of powdered polymers into monolithic material. Taking low temperature relaxation into account it was concluded t h a t polymer glasses are structurally heterogeneous. A study of the deformation and relaxation of crosslinked polymer systems leads to the conclusion t h a t the network in the polymers studied is statistically het*~'rogeneous. Intermolecular chemical bonds during the formation of polymers are mainly localized inside structural elements, which have little effect on forced elasticity in early stages of deformation. Structural heterogeneity was also demonstrated in experiments of total compression. An interesting feature of this type of deformation is the fact that various structural elements with different moduli of volumetric compression became sequentially involved in deformation. An important consequence of the structural heterogeneity of amorphous polymers is their mechanical behaviour in adsorptive media. Differences in the behaviour of polymer glasses in air and in an adsorptive medium are due to the fact that new interfaces are formed along the boundaries of various structural elements of polymers. Using a combination of structural and physical and mechanical results a model is proposed for the supermolecular packing of amorphous polymers which is based on concepts of fibrils in folded domains, joined by continuous chains. The domain-fibrillar structure was observed in electron microscope patterns obtained with thin polymethylmethacrylate fihns. The lecturer gave a detailed description of this model and the properties of polymers which follow from this interpretation. Three papers were read at the e.vening session held under the chaiiznanship of N. A. Plate, Corr. Member of the U.S.S.R. Academy of Sciences. The paper by Acad. B. A. Dolgoplosk was concerned with the nature of active centres and chain microstructure in ionic coordination polymerization of di{-nes and cyclo-olefms. New possibilities were discovered for the study of the type of active centres and the mechanism of stereo-regulation on using individual organo-metallic transition metal compounds as polymerization catalysts. The lecturer demonstrated these possibilities using several examples. A kinetic study of pol3rmerization enables us to examine the mechanism of stereoregulation from new standpoints. According to the new ideas, diene always acts as a bidentate ligand, coordinated with metal with both double bonds in cis-conformation, its incor-
3238
P . V . KozLov
poration in the active centre resulting in a c/s-unit. I n the active centre the c i s - u n i t is isomerized into a t r a m - u n i t (anti-sym-isomerization). The ratio between cis and trans units is determined by the velocity ratio of chain extension and isomerization of the active centre. Everything that reduces the rate of extension and increases the "life" of the end u n i t is accompanied by an increase in the proportion of t r a n s - u n i t s . This is brought about, for example, b y a reduction in monomer concentration, electron-donor solvating additives, etc. The lecturer illustrated the conclusions drawn by concrete examples. The problem concerning the formation mechanism of 1,2(3,4)-units was also examined. Finally, he dealt with investigations carried out in his laboratory which showed, using various cyelo-olefms, t h a t very high molecular weight polymers are formed in the initial stage of polymerization. ]-Ience it follows that the reaction follows a chain mechanism. The formation in some cases of cyclopropane and methylcyclopropane from ethylene formed the basis of the assumption concerning the carbene nature of active centres. A favourable factor for carbene formation is their stabilization with transition metals. A reduction of the reactivity of carbenes in the composite state increases selectivity a n d the possibility of application to chain processes. Investigations show that in dilute solutions at room temperature these catalysts result in a chain process of cycle-decomposition of linear polybutadiene and the formation of cyclic oligomer molecules which retain initial unsaturation. This illustrates the inverse nature of the process. A paper was read by M. M. Ketch, Corr.-Member of the U.S.S.R. Academy of Sciences concerning rigid chain polymer macromolecules. He noted that considerable experimental information has now accumulated in the field synthesis, study of the structure and properties of rigid chain polymers, which shows that apart from the effect of chemical structure, molecular and supermolecular macromolecular structure are of considerable significance. Using polymers with rings in the chain the lecturer examined relations affecting chain rigidity, the ability to soften and crystallize and the heat stability of macromolecules. Special attention was given to the structure of aromatic and heterocyclie units, the regularity of arrangement along the chain, the presence of side groups in the rings, "hinged" atoms and modifiers. Some theoretical and experimental information was given concerning internal rotation around the -- O-- link diphenyloxide model compounds and various aromatic polyimides. Using ladder type and ladder type-block plymers the prospect of using two chain polymers and the need for further investigation to develop three chain polymers which can ensure high heat stability of polymers, was indicated. Finally, a paper was read b y L. B. Stroganov in the evening session concerning the application of computers to analyse macromoleeular micro-structure by high resolution NMR. The general system of NMR spectroscopic studies of polymer chain microstructure was analysed. A serious difficulty of these investigations is the considerable width of spectroscopic lines, which produces poor resolution in NMR spectra of polymers. To overcome this difficulty, the experimental form of the line of a poorly resolved spectrum was simulated using a computer and o p t i m u m model parameters sought. The method was carried out in two forms: 1) research system of programmes for large machines, 2) dialogue methods using small computers, video-screen display programming to analyse the proximity of experimental and model spectra. The methods developed may be used to investigate the micro-block nature of MMAstyrene copolymers and the microstructure of products of partial hydrolysis of syndiotactic PMMA. I n the first case computer analysis of the form of the line of phcnyl protons made it possible to obtain information concerning micro-block nature independent of stereo-isomer chain structure; in the second case--it enabled a quantitative evaluation to
H e r m a n F. Mark
3239
be made of the " n e i g h b o u r " effect in hydrolysis using results of the complete triade microstructure. The possibility was then emphasized of using a h u m a n - c o m p u t e r system with information exchange on a video-channel. The visual motion of macromoleeules in solution was examined as an example within the framework of a rotary-isomer lattice model on a plane square lattice using a mini computer.
Translated by E. SEMERE
PERSONALITIES HERMAN F. MARK (On his 80th birthday)* P. V. KOZLOV HERMAN F. MARK--hon0rary Professor of the New York Polytechnic, foreign member of the U.S.S.R. Acad e m y of Sciences was 80 years old on 3 May, 1975. The name of Prof. Mark is well known among scientists all over the world. The development of the science of high molecular weight compounds as an independent branch of science combining organio and physical chemistry and solid state physics is linked with his name. He was among the first scientists who, as early as the beginning of the 30's, was fully aware of the enormous prospects of using polymer materials and sought to establish a scientific basis in this field, which at that time had not yet attracted serious at t en t i o n among classical chamists. Mark was born, brought up and received his chemical education in Vienna. He then worked in Germany at the Berlin University, I n s ti t u t e of Fibre Chemistry, in the Research Centre of Farben Industrie. I n this period be was in close collaboration with well-known chemists such as Schlenk, Polanyi, Wiegner, Suplard and others. Returning to Vienna in 1932 Mark became head of the first Chemical I n s t i t u t e of Vienna University; however, when the Nazis came to power and occupied Austria he was compelled to emigrate in 1938. In 1940 Mark settled in the U.S.A. and all his subsequent work was linked with the Brooklyn Polytechnic (recently renamed the New York Polytechnic). His early investigations of the deformation mechanism of metals, the structure of graphite and rhombic sulphur received universal recognition and greatly contributed to popularizing X- r a y analysis among chemists. Mark himself used this method successfully for the first time to study natural high molecular weight compounds: natural rubber, cellulose, silk and chitin. He later carried out fundamental investigations to elucidate high elasticity, relations which govern the behaviour of polymers in solutions and examined the form of macromolecules. The introduction of small angle X - r a y scattering, which is of considerable significance in identifying polymer structure is linked with Mark's name. The Mark-Houwinck equation relates the viscosity of dilute polymer solutions and chain length and up to now probably remains one of the most widely used methods for describing macromolecul es. * Vysokomol. soyed. A17: No. 12, 2819, 1975.
3235
firmed that the strength of C--S bonds of poly~ner I I is higher, the stability of polysulphone-arylates to the effect of temperature being determined by the heat resistance of ester bonds.
Tra~slated by E. SEMERE REFERENCES
1. C. T. HODGES and R. S. MATTSON, Analyt. Chem. 37: 1065, 1965 2. A. I. SIDNEV, Yu. V. KHVASHCHEVSKAYA and I. A. ZUBKOV, Pla~t. massy, No. 6, 61, 1968 3. A. A. KUL'KOV, Dissertation, 1973 4. I. V. ZHURAVLEVA, Dissertation, 1965 5. L. I. DANILINA, E. N. TELESHOV and A. N. PRAVEDNIKOV, Vysokomol. soyed. A16: 581, 1974 (Translated in Polymer Sci. U.S.S.R. 16: 3, 672, 1974)
REPORTS KARGIN LECTURES* P. V. KozLov THE Kargin lectures were held m the Chemical Faculty of the Moscow State University on 23rd J a n u a r y 1975, the fifth series since their inception (1971). This particular type of contact between a wide circle of specialists in the field of polymers is becoming a tradition of Soviet polymer science in respect for the memory of Academician V. A. Kargin, the eminent scientist of our country. The fifth Kargin Lectures were opened by V. A. Kabanov, President of the morning session, Corr. Member of the U.S.S.R. Academy of Sciences, who described to the audience the thematic trend of these lectures and threw light on some aspects of V. A. Kargin's scientific activity. As in previous lectures, the first paper read by A. B. Zezin was of a memorial nature a n d briefly reviewed V. A. Kargin's work in the field of polymer electrolytes. I n the course of his entire scientific activity in the field of polymers V. A. Kargin gave particular att e n t i o n to the study of polymer elctrolytes. V. A. Kargin's interest in polyeleetrolytes was due to the fact that these polymers are very sensitive to changes of surrounding atmosphere which result in various structural formations. Using experimental results concerning the structural morphology of polymer electrolytes in solution V. A. Kargin formulated basic theories concerning the structure of amorphous polymers and types of primary supermolecular formation in them. The lecturer was concerned with details of V. A. Kargin's studies both of structure formation of irregular and regular polyolectrolytes and the link between these processes and similar effects in biological systems. Investigations by V. A. Kargin concerning the structure of polyelectrolyto complexes as models of complex biological systems and polymerization of ionogen monomers on polyelectrolyte matrices, which had been started under the direct guidance of V. A. Kargin, form this part of the studies. The lecturer subsequently dealt with V. A. Kargin's investigations of the simulation * Vysokomol. soyed. A17- No. 12, 2815--2818, 1975.
3236
P . V . KozLov
of functioning of biological systems which, in particular, resulted in formation of macromolecular catalysts. The principle of activity of these catalysts is similar to that of fermentation. The lecturer also d(~alt with V. A. Kargin's work in developing ion exchange polymers and macromolecular complex('s, examining processes of stabilization of suspensions and soils using polymer electrolytes, studying properties and structure of some albumens and mainly gelatin and finally, the use of polyelectrolytes for medicinal purposes. Finally, the lecturer briefly described V. A. Kargin's views concerning means of developing views about polymer electrolytes, the strategy of scientific research in this field, compared with the field of conventional polymers, the large scale production of which has now reached significant proportions all over the world. The morning session of the Kargin lectures was also concerned with three further papers in the field of polymer synthesis, structure and'mechanical properties. The first of these papers was read by Prof. A. N. Pravednikov about the synthesis of polyhetero-arylenes by ring formation using isomerization. Studies were reviewed which were mainly carried out under laboratory conditions by isomerization synthesis of heat-resistant polymers. Methods of synthesis were examined of new m o n o m e r s - - a r o m a t i c bis(o-aminonitriles) and bis-(o-chloroformylnitriles) and polyheteroarylenes prepared from them without the separation of volatile products at the stage of ring formation. A description was given of the structure and properties of several new polymers obtained by ring formation using isomerization: polyiminoimides, polyquinazolones, polyiminoquinazolones, polyquinazoline diones, polyiminoquinazoline pyrrolones, etc. Special attention was paid to the synthesis of heat-resistant polymers without liberation of volatile products both at the stage of pre-polymer formation and at the stage of ring formation. The advantages were indicated of synthesizing heat-resistant polymers by isomerization, compared with well-known two-stage methods. Acad. Kh. U. Usmanov, of the Uzb. S.S.R. Academy of Sciences then described the success achieved on the field of structural investigations of cellulose and cellulose derivatives. He emphasized that investigation of the supermolecular structure of cellulose and cellulose derivatives over several years in Uzbekistan provided convincing evidence supporting V. A. Kargin's theories about the structural dependence of properties of polymers. Cellulose which is a rigid chain polymer with a fairly regular chain structure and intensive molecular interaction, is characterized by a tendency to form various kinds of molecular ordering both in the course of biosynthesis and during precipitation from solutions. As a result of biosynthesis primary elements of supermolecular organization--microfibrils are formed, the transverse dimension of which is 60-80 A. Micro fibrils are characterized by the formation of thin sub-layers or lamellae which form the main mass of oriented cellulose fibres, a secondary wall. A similar structure combined with high molecular weight ensures high strength and modulus of cellulose fibres with retention of physical and mechanical properties in the wet state. F r o m an analysis of literature results and electron microscope studies when forming models and systems of the structure of cellulose fibres, the author proposes to adopt the following principles: natural cellulose macromolecules no doubt have straightened conformation; for cellulose hydrate fibres chain particles m ay exist in a folded conformation. Microfibrils have a heterogeneous structure with statistical alternation of large and small regions. The dimensions of these ranges m a y differ considerably according to the type of cellulose preparation. By forming fibres under mild conditions highly oriented elongation m ay be achieved which results in a structural change-over of fibrillar elements, accompanied by a noticeable increase in the length of ordered sections. This principle forms the basis of new types of cellulose hydrate fibres, e.g. "polynose" fibres. A h i g h orientation of microfibrils and paral-
Kargin lectures
3237
lel chain arrangement in structural elements ensure considerable fibre strength, but reduce breaking elongation and stability to repeated deformation. At the same time, changing conditions of precipitation and orientation elongation a structure m a y be formed which in m a n y ways is similar to the structure of high strength natural fibres. The same correlation between structure and properties was found in erosslinked, cyanethylated graft and a c t i v at ed cellulose. Results convincingly confirm the relation between supermolecular structure and properties of cellulose materials and the considerable possibilities offered by electron microscope methods of studying polymers. These have been extensively developed in this country and are due ~o V. A. Kargin who showed considerable interest and constant at t en t i o n in this field of poly~ner science. Finally, 8 paper was read at the morning session by S. A. Arzhakov concerning the structural and mechanical behaviour of polymer glass. A study of reduction of polymer glass samples subjected to forced elastic deformation shows that forced elastic deformation generally comprises two components. One relaxes at temperatures lower than the glass temperature, and the other in the glass transition range. The ratio between the low and high temperature components of forced elastic deformation and subsequent relaxation is determined by the overall degree of deformation and the temperature of deformation. This is used to explain some features of the conversion of powdered polymers into monolithic material. Taking low temperature relaxation into account it was concluded t h a t polymer glasses are structurally heterogeneous. A study of the deformation and relaxation of crosslinked polymer systems leads to the conclusion t h a t the network in the polymers studied is statistically het*~'rogeneous. Intermolecular chemical bonds during the formation of polymers are mainly localized inside structural elements, which have little effect on forced elasticity in early stages of deformation. Structural heterogeneity was also demonstrated in experiments of total compression. An interesting feature of this type of deformation is the fact that various structural elements with different moduli of volumetric compression became sequentially involved in deformation. An important consequence of the structural heterogeneity of amorphous polymers is their mechanical behaviour in adsorptive media. Differences in the behaviour of polymer glasses in air and in an adsorptive medium are due to the fact that new interfaces are formed along the boundaries of various structural elements of polymers. Using a combination of structural and physical and mechanical results a model is proposed for the supermolecular packing of amorphous polymers which is based on concepts of fibrils in folded domains, joined by continuous chains. The domain-fibrillar structure was observed in electron microscope patterns obtained with thin polymethylmethacrylate fihns. The lecturer gave a detailed description of this model and the properties of polymers which follow from this interpretation. Three papers were read at the e.vening session held under the chaiiznanship of N. A. Plate, Corr. Member of the U.S.S.R. Academy of Sciences. The paper by Acad. B. A. Dolgoplosk was concerned with the nature of active centres and chain microstructure in ionic coordination polymerization of di{-nes and cyclo-olefms. New possibilities were discovered for the study of the type of active centres and the mechanism of stereo-regulation on using individual organo-metallic transition metal compounds as polymerization catalysts. The lecturer demonstrated these possibilities using several examples. A kinetic study of pol3rmerization enables us to examine the mechanism of stereoregulation from new standpoints. According to the new ideas, diene always acts as a bidentate ligand, coordinated with metal with both double bonds in cis-conformation, its incor-
3238
P . V . KozLov
poration in the active centre resulting in a c/s-unit. I n the active centre the c i s - u n i t is isomerized into a t r a m - u n i t (anti-sym-isomerization). The ratio between cis and trans units is determined by the velocity ratio of chain extension and isomerization of the active centre. Everything that reduces the rate of extension and increases the "life" of the end u n i t is accompanied by an increase in the proportion of t r a n s - u n i t s . This is brought about, for example, b y a reduction in monomer concentration, electron-donor solvating additives, etc. The lecturer illustrated the conclusions drawn by concrete examples. The problem concerning the formation mechanism of 1,2(3,4)-units was also examined. Finally, he dealt with investigations carried out in his laboratory which showed, using various cyelo-olefms, t h a t very high molecular weight polymers are formed in the initial stage of polymerization. ]-Ience it follows that the reaction follows a chain mechanism. The formation in some cases of cyclopropane and methylcyclopropane from ethylene formed the basis of the assumption concerning the carbene nature of active centres. A favourable factor for carbene formation is their stabilization with transition metals. A reduction of the reactivity of carbenes in the composite state increases selectivity a n d the possibility of application to chain processes. Investigations show that in dilute solutions at room temperature these catalysts result in a chain process of cycle-decomposition of linear polybutadiene and the formation of cyclic oligomer molecules which retain initial unsaturation. This illustrates the inverse nature of the process. A paper was read by M. M. Ketch, Corr.-Member of the U.S.S.R. Academy of Sciences concerning rigid chain polymer macromolecules. He noted that considerable experimental information has now accumulated in the field synthesis, study of the structure and properties of rigid chain polymers, which shows that apart from the effect of chemical structure, molecular and supermolecular macromolecular structure are of considerable significance. Using polymers with rings in the chain the lecturer examined relations affecting chain rigidity, the ability to soften and crystallize and the heat stability of macromolecules. Special attention was given to the structure of aromatic and heterocyclie units, the regularity of arrangement along the chain, the presence of side groups in the rings, "hinged" atoms and modifiers. Some theoretical and experimental information was given concerning internal rotation around the -- O-- link diphenyloxide model compounds and various aromatic polyimides. Using ladder type and ladder type-block plymers the prospect of using two chain polymers and the need for further investigation to develop three chain polymers which can ensure high heat stability of polymers, was indicated. Finally, a paper was read b y L. B. Stroganov in the evening session concerning the application of computers to analyse macromoleeular micro-structure by high resolution NMR. The general system of NMR spectroscopic studies of polymer chain microstructure was analysed. A serious difficulty of these investigations is the considerable width of spectroscopic lines, which produces poor resolution in NMR spectra of polymers. To overcome this difficulty, the experimental form of the line of a poorly resolved spectrum was simulated using a computer and o p t i m u m model parameters sought. The method was carried out in two forms: 1) research system of programmes for large machines, 2) dialogue methods using small computers, video-screen display programming to analyse the proximity of experimental and model spectra. The methods developed may be used to investigate the micro-block nature of MMAstyrene copolymers and the microstructure of products of partial hydrolysis of syndiotactic PMMA. I n the first case computer analysis of the form of the line of phcnyl protons made it possible to obtain information concerning micro-block nature independent of stereo-isomer chain structure; in the second case--it enabled a quantitative evaluation to
H e r m a n F. Mark
3239
be made of the " n e i g h b o u r " effect in hydrolysis using results of the complete triade microstructure. The possibility was then emphasized of using a h u m a n - c o m p u t e r system with information exchange on a video-channel. The visual motion of macromoleeules in solution was examined as an example within the framework of a rotary-isomer lattice model on a plane square lattice using a mini computer.
Translated by E. SEMERE
PERSONALITIES HERMAN F. MARK (On his 80th birthday)* P. V. KOZLOV HERMAN F. MARK--hon0rary Professor of the New York Polytechnic, foreign member of the U.S.S.R. Acad e m y of Sciences was 80 years old on 3 May, 1975. The name of Prof. Mark is well known among scientists all over the world. The development of the science of high molecular weight compounds as an independent branch of science combining organio and physical chemistry and solid state physics is linked with his name. He was among the first scientists who, as early as the beginning of the 30's, was fully aware of the enormous prospects of using polymer materials and sought to establish a scientific basis in this field, which at that time had not yet attracted serious at t en t i o n among classical chamists. Mark was born, brought up and received his chemical education in Vienna. He then worked in Germany at the Berlin University, I n s ti t u t e of Fibre Chemistry, in the Research Centre of Farben Industrie. I n this period be was in close collaboration with well-known chemists such as Schlenk, Polanyi, Wiegner, Suplard and others. Returning to Vienna in 1932 Mark became head of the first Chemical I n s t i t u t e of Vienna University; however, when the Nazis came to power and occupied Austria he was compelled to emigrate in 1938. In 1940 Mark settled in the U.S.A. and all his subsequent work was linked with the Brooklyn Polytechnic (recently renamed the New York Polytechnic). His early investigations of the deformation mechanism of metals, the structure of graphite and rhombic sulphur received universal recognition and greatly contributed to popularizing X- r a y analysis among chemists. Mark himself used this method successfully for the first time to study natural high molecular weight compounds: natural rubber, cellulose, silk and chitin. He later carried out fundamental investigations to elucidate high elasticity, relations which govern the behaviour of polymers in solutions and examined the form of macromolecules. The introduction of small angle X - r a y scattering, which is of considerable significance in identifying polymer structure is linked with Mark's name. The Mark-Houwinck equation relates the viscosity of dilute polymer solutions and chain length and up to now probably remains one of the most widely used methods for describing macromolecul es. * Vysokomol. soyed. A17: No. 12, 2819, 1975.