Synthesis and Characterization of Novel Substituted Polymethylenes

由1，2-二取代乙烯聚合而成的聚合物，如富马酸二烷基酯（DRF）和N-取代马来酰亚胺，可视为取代聚亚甲基。这种聚合物在结构上不同于常规的乙烯基聚合物，常规的乙烯基聚合物的主链由包括未取代的亚甲基基团的重复单元组成。1，2-二取代乙烯由于存在严重的空间位阻，一直被认为不容易均聚。在这方面，DRF的自由基聚合的绝对速率常数测定表明，受阻的传播和终止的平衡允许聚合物的形成。对DRF加成的相当大的空间位阻也已通过2-氰基-1-丙基自由基对DRF的异常低的反应性得到证明，导致参与初级自由基终止。动态光散射测量显示了聚合物链的刚性。制备了具有不同取代基的马来酰亚胺的聚合物并进行了聚合。所有的聚合物是热稳定的，通过热重分析证实。马来酰亚胺的共聚可提高乙烯基聚合物的热稳定性。由含N-长链烷基的马来酰亚胺合成的聚合物已被用作气体渗透膜，具有较高的Tg和较快的渗透速度。N-三烷基硅基马来酰亚胺经聚合、酸解得到高分子量聚马来酰亚胺。还通过异戊烯衍生物、巴豆酸酯、苊烯和山梨酸酯的聚合反应合成了取代聚亚甲基。

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.