Two-step degradable ABAC-type periodic poly(cyclic acetal)s synthesized by sequence-programmed monomer formation and subsequent polyaddition based on cyclotrimerization of one vinyl monomer and two aldehydes
Two-step degradable ABAC-type periodic poly(cyclic acetal)s synthesized by sequence-programmed monomer formation and subsequent polyaddition based on cyclotrimerization of one vinyl monomer and two aldehydes
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DOI：
10.1016/j.giant.2023.100159
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发表时间：
2023-04
期刊：
影响因子：
7
通讯作者：
Tadashi Naito;Arihiro Kanazawa;S. Aoshima
中科院分区：
文献类型：
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作者：
Tadashi Naito;Arihiro Kanazawa;S. Aoshima
采用两步法合成abac型周期性聚（环缩醛）：由一种乙烯基单体和两种双功能醛（二苯二醛或对苯二甲酸）依次合成一种环状三聚体，并与另一种乙烯基单体进行连续的环三聚化反应。1,1-二苯乙烯（DPE）的使用对高收率合成环三聚体具有重要意义，因为DPE的位阻抑制了连续的环三聚化反应和其他副反应。aba型序列编程环三聚体由一个DPE分子（单元B）和两个二醛分子（单元A）组成，具有两个未反应的醛基团；因此，环三聚体成功地与乙烯醚（单元C），如2-氯乙基VE （CEVE）和2-甲基-1-丙烯醚（EMPE）进行了连续的环三聚化。得到了两个苯基环和ve衍生侧链交替排列的abac型周期性聚（环缩醛）。主链上的两种环状缩醛结构表现出不同的酸降解性。事实上，ceve衍生的环缩醛结构在60°C的酸性条件下选择性地降解了15分钟，随后dpe衍生的环缩醛结构在24小时内降解。此外，abac型周期性聚合物表现出良好的热性能，这归因于环缩醛结构。
ABAC-type periodic poly(cyclic acetal)s were synthesized via a two-step method consisting of the synthesis of a sequence-programmed cyclic trimers from one vinyl monomer and two bifunctional aldehydes (isophthalaldehyde or terephthalaldehyde) and the successive cyclotrimerization of the cyclic trimer with another vinyl monomer. The use of 1,1-diphenylethylene (DPE) was important for synthesizing the cyclic trimer in high yield because the successive cyclotrimerization and other side reactions were suppressed due to the steric hindrance of DPE. The ABA-type sequence-programmed cyclic trimer consisting of one DPE molecule (unit B) and two dialdehydes (unit A) possesses two unreacted aldehyde moieties; hence, the cyclic trimer successfully underwent successive cyclotrimerization with vinyl ethers (VEs) (unit C), such as 2-chloroethyl VE (CEVE) and ethyl 2-methyl-1-propenyl ether (EMPE). As a result, ABAC-type periodic poly(cyclic acetal)s with alternately arranged two phenyl rings and VE-derived side chains were produced. The two types of cyclic acetal structures in the main chain exhibited different acid degradability. Indeed, the CEVE-derived cyclic acetal structures were selectively degraded under acidic conditions at 60 °C for 15 min, which was followed by the subsequent degradation of the DPE-derived cyclic acetal structures in 24 h. In addition, the ABAC-type periodic polymers exhibited good thermal properties, which were attributed to the cyclic acetal structures.