Synthesis and Characterization of Novel Substituted Polymethylenes

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Polymers from 1, 2-disubstituted ethylenes such as dialkyl fumarate (DRF) and N-substituted maleimide can be regarded as substituted polymethylenes. Such polymers are structurally differentiated from conventional vinyl polymers of which the main chains consist of the repeating units involving unsubstitued methylene gyoup. 1, 2-Disubstituted ethylenes had been thoguht to be reluctant to homopolymerize because of severe steric hindrance. In this regard, the absolute rate constants determined for radical polymerization of DRF revealed that the balance of the hindered propagation and termination allows polymer formation. The considerable steric hindrance against addition to DRF has also been evidenced by an exceptionally low reactivity of 2-cyano-1-propyl radical toward DRF resulting in participation to primary radical termination. Dynamic light scattering measurement of poly (DRF) exhibited the rigid nature of the polymer chain. Polymerization of the maleimides bearing various substituents were prepared and polymerized. All the polymers were thermally stable as confirmed by thermogravimetric analysis. Copolymerization of the maleimides could improve the thermal stability of vinyl polymers. The polymers from the maleimide with a N-long alkyl chain have been utilized as gas permeable membranes, and the relatively high T_g and fast permeation were noted. N-(Trialkylsilyl) maleimide was polymerized and subsequent acid hydrolysis gave high molecular weight poly (maleimide). The substituted polymethylenes were also synthesized by polymerization of itaconic derivatives, crotonic ester, acenaphthylene and sorbic ester.