Synthesis and Characterization of Novel Substituted Polymethylenes

1，2-二取代乙烯的聚合物，如富马酸二烷基(DRF)和N-取代马来酰亚胺，可视为取代的聚亚甲基。这种聚合物在结构上与传统的乙烯基聚合物不同，传统的乙烯基聚合物的主链由含有未取代的亚甲基环基的重复单元组成。由于严重的空间位阻，1，2-二取代乙烯一直不愿均聚。在这方面，DRF自由基聚合的绝对速率常数表明，受阻的传播和终止之间的平衡允许聚合物的形成。2-氰基-1-丙基自由基对DRF的反应性极低，导致参与了初级自由基的终止，这也证明了对DRF加成的相当大的空间位阻。聚合物(DRF)的动态光散射测量显示了聚合物链的刚性性质。制备了含不同取代基的马来酰亚胺的聚合反应。热重分析表明，所有聚合物都是热稳定性的。马来酰亚胺的共聚可以提高乙烯基聚合物的热稳定性。N-长烷基链的马来酰亚胺聚合物被用作透气膜，具有较高的玻璃化温度和较快的渗透速度。N-(三烷基硅基)马来酰亚胺聚合后经酸解得到高相对分子质量的聚马来酰亚胺。还通过衣康酸衍生物、丁二醇酯、榄香烯和山梨酸酯的聚合反应合成了取代的聚亚甲基。

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.