An electron-microscopic study of pemosores

An electron-microscopic study of pemosores

AN ELECTRON-MICROSCOPIC STUDY OF PEMOSORES* V. V. KORSHAK, K. K. MOZGOVA,Y~. V. YEGOROVA, K. Z. GUMARGALIYEVAand ¥E. M. BELAVTSEVA Institute of Hetcro...

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AN ELECTRON-MICROSCOPIC STUDY OF PEMOSORES* V. V. KORSHAK, K. K. MOZGOVA,Y~. V. YEGOROVA, K. Z. GUMARGALIYEVAand ¥E. M. BELAVTSEVA Institute of Hetcro-organic Compounds, U.S.S.R. Academy of Sciences (Received 30 June 1965) THE multi-graft copolymers that we have called pemosores form a new type of copolymer in which a number of different vinyl polymers are grafted on to a polymer film or fibre. We have shown previously that pemosores can be obtained by grafting vinyl monomers on to hetero-chain polymers [1]. Specimens of the original polymers are first held in air at 110 ° for 3 minutes and are then heated with the vinyl monomers. The grafting operation is repeated several times with different monomers in succession. In this way we have synthesized pemosores with different combinations of the original and grafted polymers. Some of these contained as many as five different vinyl polymers, for example polystyrene, polymethylmethacrylate, polymethacrylic acid etc. The method of repeated grafted has enabled pemosores with high yields of grafted polymer to be obtained (1000% and above). Pemosores possess a number of interesting properties. Despite their high molecular weight they are soluble in tricresol. A detailed study of these properties is reported in reference [2]. This communication presents the results of electronmicroscopic and X-ray studies of pemosores. Grafted films based on polyethyleneterephthalate (PETP) and poly-~-caproamide were studied in the electron microscope in the form of carbon-platinum replicas, prepared by the method described by Bradley [3]. With these replicas it is possible to reproduce the surface structure of the specimen with high resolution. The pemosores were studied in a UEMV-100 electron microscope. The surfaces of the following materials were studied: 1) untreated PETP, 2) P E T P grafted with polystyrene, once at two levels of 17% and 166%, twice at levels of 30% and 155% and four times (total increase in weight 200% calculated on the original film weight), 3) P E T P grafted with polymethylmethacrylate once (1.5%) and twice (235%), 4) P E T P grafted with polymethacrylic acid (2%), 5) P E T P with four alternate graftings of polystyrene and polymethylmethacrylate (195%), 6) poly-~-caproamide grafted with polystyrene once (19%) anti,four times (175%), 7) poly-e-caproamide with four alternate graftings of polystyrene and polymethylmethacrylate (540%) and 8) poly-~-caproamide grafted with polymethylmethacrylate (4%--once, 215%--twice). * Vysokomol. soyed. 8: No. 8, 1365-1367, 1966. 1499

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FIOS. 1-3 FIG. 1. Untreated polyethyleneterephthalate (PETP). FIG. 2. PETP with different quantities of polystyrene: a--17%, b--166%, c--30 and 155% (twofold), d-- 200% (fourfold). FIO. 3. PETP with alternate graftings of polystyrene and polymethylmethacrylate (195%), fourfold.

Electron-microscopic study of pemosores

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Figure 1 shows an electron micrograph of the surface of untreated P E T P . It is seen that before grafting the film has an almost uniform surface with only slight relief. Only isolated bands and projections are seen and these are obviously produced in the process of preparation of the film. Fine globules measuring ~ 500 /~ are distributed over the entire surface, reflecting the morphological structure of the film. Study of grafted P E T P in the electron microscope showed that grafting produces a marked change in the morphological structure of the surface, the change becoming greater with increase in the quantity of grafted monomer. It should be noted that the nature of the grafting monomer also has an effect on the change in the surface of the grafted film. Grafting of styrene causes the greatest change in the surface structure. Grafting of methyl methaerylate and methacrylic acid produces mainly globular formations on the surface of the original film. Figures 2 a-d show micrographs of the surface of P E T P with different quantities of grafted polystyrene. I t is seen from Fig. 2a that after grafting of 17% of styrene lumpy projections of different sizes appear (roughly from 500 A to 1/~). The height and diameter of the projections increase with increase in the quantity of grafted monomer. I n isolated cases we were able to see individual discs on a smooth surface (Fig. 2d). These were obtained after fourfold grafting of styrene to P E T P to the extent of 200~. Similar pictures were obtained with specimens of P E T P alternately grafted with polystyrene and polymethylmethaeryla¢~ (total quantity 195~) (Fig. 3). However in this case the discs were not uniform in height, which increased from the centre to the edge. The surface of these specimens is reminiscent of the crater of a volcano. Grafting of methylmethacrylate alone produces globular formations measuring ~ 1000 A. Larger globules are found when the degree of grafting is increased (Figs. 4a and b). In the case of methacrylic acid well defined globules are seen in the micrographs even when the quantity of grafted polymer is small (Fig. 5). In contrast to the surface of P E T P the surface of poly-e-caproamide contains a large number of globules measuring from 500 to 1000 A (Fig. 6). Grafting of monomers causes a marked alteration in the morphology of the surface. The electron micrographs show t h a t all the monomers t h a t we used for grafting give rise to projections with clear boundaries. Films of P E T P did not give this type of picture. The grafted polymer is predominantly arranged in terraces regardless of the nature and quantity of the monomer. Figure 7a shows an electron micrograph o f poly-~-caproamide with 19~/o of grafted polystyrene and Fig. 7b corresponds to 175% of the same monomer (fourfold grafting). When the degree of grafting is low globules are encountered in addition to terraces. When the degree of alternate grafting of styrene and methyl methacrylate is high ( 5 4 0 ° ) a highly complex surface relief is obtained, with several superimposed layers of grafted polymer (Fig. 8).

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FIGS. 4-8 FIG. 4. a - - P E T P with polymethylmethemrylate (1"5 °/o), b -- the same with grafted polyme~hylmethaerylate (2350/0), twofold. FIG. 5. P E T P with polymethacrylie acid (2%). FIG. 6. U n t r e a t e d poly-8-eaproamide. FIG. 7. a -- Poly-6-caproamide with polystyrene ( 19V/o), b -- the same with grafted polystyreno ( I~75% ), fourfold. FIG. 84 Poly:e-caproamide with alternate graftings of polystyrene and polymethylmet~hacrylate (540%), fourfold.

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Thus the electron-microscopic study of replicas of the surface of the graft copolymers has shown that there is a difference in the pattern of grafting of vinyl monomers on to P E T P and poly-~-caproamide. There are also differences depending on the nature and quantity of the grafted monomer. An X-ray s t u d y of grafted P E T P and poly-e-eaproamide films showed that grafting takes place on the surface of the initial copolymer, without affecting the crystalline regions. Increase in the proportion of grafted polymer results in the production of an X-ray pattern of the completely amorphous type, i.e. it is only the nature of the grafted monomer that is clearly displayed, as we also found in the electron mierographs. The authors express their gratitude to D. Ya. Tsvankin for recording the Xradiograms of the pemosores. CONCLUSIONS

(1) An electron-microscopic study of pemosores has shown that grafting alters the morphology of the surface considerably, the change being greater the greater the quantity of grafted monomer. (2) I t was found that there is a different pattern of grafting of vinyl monomers on to polyethyleneterephthalate and poly-e-caproamide. There are also differences associated with the nature of the grafted monomer. Translated by E. O. PHILLIPS REFERENCES

1. V. V. KORSHAK, K. K. MOZGOVA and Yu. V. YEGOROVA, Plast. m~ssy, No. 2, 1 1966 2. B. V. LOKSHIN, V. V. KORSHAK, K. K. MOZGOVA and Yu. V. YEGOR0VA, Dokl. Akad. Nauk SSSR 166: 118, 1966 3. D. E. BRADLEY, Brit. J. Appl. Phys. 1O: 198, 1959

C A T I O N - E X C H A N G E R E S I N S A N D P O L Y A M P H O L Y T E S B A S E D ON C O P O L Y M E R S OF N - V I N Y L S U C C I N I M I D E A N D D I V I N Y L B E N Z E N E * t

A. F. NIKOLXYEV and S. G. BOND~RENKO Lensoviet Technological Institute, Leningrad (Received 28 June 1965)

IN RECENT years much experimental work has been devoted to study of the production and properties of polyampholytes that function as selective ion-exchange resins. In this field we have undertaken a study of methods of preparation * Vysokomol. soyed. 8: No. 8, 1368-1372, 1966. t 8th Communication in the series "Polyvinylamine and its derivatives".