FREE-RADICAL RING-OPENING POLYMERIZATION OF 4,7-DIMETHYL-2-METHYLENE-1,3-DIOXEPANE AND "5,6-BENZO-2-METHYLENE-1,3-DIOXEPANE
FREE-RADICAL RING-OPENING POLYMERIZATION OF 4,7-DIMETHYL-2-METHYLENE-1,3-DIOXEPANE AND "5,6-BENZO-2-METHYLENE-1,3-DIOXEPANE
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DOI：
10.1021/ma00231a006
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发表时间：
1982-01-01
期刊：
影响因子：
5.5
通讯作者：
WU, SR
中科院分区：
文献类型：
--
作者：
BAILEY, WJ;NI, Z;WU, SR
为了扩展自由基开环聚合的研究以包括不同的结构并确定反应范围，通过脱卤化氢制备了两种环状乙烯酮缩醛，顺式和反式-4, 7-二甲基-2-亚甲基-1, 3-二氧杂环庚烷 (3) 和 5, 6-苯并-2-亚甲基-1, 3-二氧杂环庚烷 (5)。单体3和5的自由基聚合均在120℃下进行，基本定量开环，产生相应的聚酯。类似地，单体3和5都显示出容易与苯乙烯和甲基丙烯酸甲酯共聚，产生在加成聚合物的主链中含有酯键的共聚物，表现出几乎定量的开环。据信，开环自由基稳定性的增加和直接非开环聚合的空间位阻的增加都促进了聚合过程中自由基开环的程度。
In order to extend the study of free radical ring-opening polymerization to include diverse structures and to determine the scope of the reactions, two cyclic ketene acetals, cis-and trans-4, 7-di-methyl-2-methylene-l, 3-dioxepane (3) and 5, 6-benzo-2-methylene-l, 3-dioxepane (5), were prepared by de-hydrohalogenation. Free radical polymerizations of both monomers 3 and 5 were shown to proceed at 120 C with essentially quantitative ring opening to produce the corresponding polyesters. Similarly, both monomers 3 and 5 were shown to copolymerize readily with styreneand methyl methacrylate to produce a copolymer containing ester linkages in the backbone of the addition polymer representing nearly quantitative ring opening. Both theincreased stability of the ring-opened radical and the increase in steric hindrance to direct non-ring-opened polymerization are believed to promote the extentof free radical ring opening during polymerization.