SYNTHESIS AND POLYMERIZATION OF ALKYL 1-BICYCLOBUTANECARBOXYLATES
SYNTHESIS AND POLYMERIZATION OF ALKYL 1-BICYCLOBUTANECARBOXYLATES
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DOI：
10.1021/ma00058a001
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发表时间：
1993-03-15
期刊：
影响因子：
5.5
通讯作者：
PADIAS, AB
中科院分区：
文献类型：
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作者：
DRUJON, X;RIESS, G;PADIAS, AB
以1，1-环丁烷二羧酸为原料，采用一种适合于合成各种双环丁烷酯类化合物的实用合成路线，合成了1位上带有酯基的双环丁烷单体。利用该方法制备了四种新的双环丁烷单体，即1-双环丁烷羧酸乙酯、异丙酯、β，β，β-三氟乙酯和苯酯。这些双环丁烷羧酸酯在各种条件下进行自由基聚合。双环丁烷单体的行为与其乙烯基对应物非常相似。链转移到聚合物在一定程度上发生，特别是当取代基的大小相对较小时（甲酯）。可通过添加链转移剂来控制过高的分子量和凝胶化。温度、酯基的大小或引发剂的性质对双环丁烷聚合物主链的立体化学没有显著影响。聚（1-双环丁烷羧酸甲酯）是一种光学透明材料，折射率n（D）25 = 1.52。它的耐热降解性非常好。来自该家族的聚合物表现出令人惊讶的低T（g），这可能是由于双环丁烷聚合物主链的出乎意料的高柔性，如分子模拟所示。
Bicyclobutane monomers substituted with an ester group at the 1 position were synthesized using a practical synthesis route, starting from 1,1-cyclobutanedicarboxylic acid, which is adaptable to the synthesis of various bicyclobutane esters and can be scaled up. Four new bicyclobutane monomers were prepared using this method, namely ethyl, isopropyl, beta,beta,beta-trifluoroethyl, and phenyl 1-bicyclobutanecarboxylate. These bicyclobutanecarboxylates were subjected to free radical polymerization under various conditions. The bicyclobutane monomers behave very similarly to their vinyl counterparts. Chain transfer to polymer occurs to some extent, especially when the size of the substituent is relatively small (methyl ester). Excessively high molecular weights and gelation can be controlled by addition of a chain-transfer agent. The temperature, the size of the ester group, or the nature of the initiator has no marked influence on the stereochemistry of the bicyclobutane polymer backbones. Poly(methyl 1-bicyclobutanecarboxylate) is an optically clear material with a refractive index n(D)25 = 1.52. Its resistance to thermal degradation is excellent. Polymers from this family exhibited surprisingly low T(g)'s, which probably result from an unexpectedly high flexibility of the bicyclobutane polymer backbone, as shown by molecular modeling.