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RESEARCH PRODUCT

Copolymers with ordered chemical structure

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Copolymers with well defined sequences can be obtained for instance by ring-opening polymerization of selected acetals. In this way regular copolymers of formaldehyde and ethylenoxide of the following structure are available2. In the same way some other copolymers with formaldehyde units were obtained. Of special interest are unsaturated polyacetales; for instance3 They can be modified by chemical reactions, for instance by hydrogenation, addition of bromine, iodine isocyanate or epoxidation. Recently a bicyclic unsaturated cycloacetal was prepared and polymerized4 Branched copolymers with a definite number of uniform sidechains are prepared by N-alkylation of polyamides5 The dependence of the properties on the length o f the alkyl groups is discussed. Some o f these highly ordered polymers show a strong side-chain crystallinity. Another type of regular branched polymers is obtained by topochemical polymerization of long-chain diacetylenes6,7. These polymers are o f special interest because they are soluble and fusible. The monomer-free solid polydiacetylenes are red, but their solutions in chloroform, THF or toluene are yellow. The good solubility allows molecular weight determination by light scattering, GPC and osmometry and also spectroscopical studies (UV, NMR). The DSC shows two endothermic peaks which are ascribed to conformational changes in the side chain and in the backbone. These transformations are accompanied by strong colour changes from red to yellow.