Polymers with functional groups
Examples for the synthesis of functional polymers are discussed. Functional oiigomers are prepared by endcapping of oiigomers with terminal reactive groups with a functional reagent. Functionalization of a high polymer was done similarly. The synthesis of a functional monomer and its homoand copolymerization is exemplified by discussing 3-vinyisalicylic acid derivatives. Bithionol and other bisphenols were used as monomers for the synthesis of condensation polymers, i.e. polycarbonates, polyesters and polyurethanes. INTRODUCTION Polymers with functional groups are desired because of their specific chemical and spectroscopic properties, rather than their mechanical properties (1). Polymers have been synthesized which have active groups effective as catalysts (2,3) for chemical reactions or hydrogenations, UV absorbers (4-6), antioxidants (7), photo (8), thermo (9) and electro-active (10) as well as biologically active groups (11-15). Such polymers range over a diverse group of polymers and include homopolymers and copolymers, polymers of various kinds of solubility, swellability and even completely insoluble materials; they include oligomers and polymers of low, medium and high molecular weights. Polymers have been prepared in order to modify such basic chemical and physical properties as the glass transition temperature, melting point, solubility, crystallinity and other fundamental properties which depend directly upon steric requirements, polarity and interaction of functional groups. It has been estimated that polymers in the health and food industry and for the production and preservation of energy, will be the main thrust of the research development in polymer science over the next decade; as polymer engineering, polymer physics and polymer chemistry respectively were important in the development of polymer science in each of the preceeding decades. If one compares the number of meetings, symposia and seminars concerned with the aspects, preparation, characterization and utilization of polymers with functional groups, it is clear that this area is probably the field of greatest growth in polymer research devel opment. In this discussion examples of polymers with various and specific functional groups will be given but we will not stress the more traditional polymers of low or moderate molecular weights with functional groups which are used for postreactions (16,17). These polymers have the functional and reactive group either at the end of the polymer chain such as in glycidyl ether terminated-Bisphenol A epoxy polymers, or isocyanate terminated polyurethanes of low and medium molecular weight copolymers consisting of reactions of 2,4-toluene diisocyanates, or methylene-bis(4,4'-diphenyl diisocyanate) with polymeric glycols of polyethers or polyesters. Telechelic polymers which are acrylate terminated low molecular weight polyesters or polyamides and the common unsaturated polyesters where polymerizable double bonds are in the middle of the oligomeric polymer chain or phenol-, urea-, or melamine-formaldehyde prepolymers could also be classified in this category. Polymeric materials with functional groups have potential advantages or disadvantages over small molecules with functional groups as their usefulness may be related to the functional groups and/or to the polymeric nature of the substances (6,18). The importance of this behavior has been particularly well recognized in the area of polymeric pharmaceuticals or polymeric drugs but the concept can very well be applied to other areas of functional polymers. Reactions on oligomers and polymers are qualitatively similar; however, solubility of the starting material and the final reaction product may require different reaction conditions. When reactions are carried out on oligomers or polymers, the active group of the polymers may have to be further activated by introducing a more reactive group in order to guarantee