We report an improved and efficient method to prepare well-defined, structurally complex truxinate cyclobutane polymers via a thioxanthone sensitized solution state [2 + 2] photopolymerization. Monomers with varying electron density and structure polymerize in good to excellent yields to afford a library of 42 polyesters. Monomers with internal olefin separation distances of greater than 5 Å undergo polymerization via intermolecular [2 + 2] photocycloaddition readily, as opposed to the intramolecular [2 + 2] photocycloaddition observed in monomers with olefins in closer proximity. Use of a continuous flow reactor decreases reaction time, increases polymer molecular weight, and decreases dispersity compared to batch reactions. Furthermore, under continuous flow, polymerization is readily scalable beyond what is possible with batch reactions. This advancement ushers truxinate cyclobutane-based polyesters, which have been historically limited to a few examples and only research scale quantities, to the forefront of development as new materials for potential use across industry sectors.

中文翻译：

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获取环丁烷聚合物：通过高效连续流 [2 + 2] 光聚合克服合成挑战


我们报告了一种改进且有效的方法，通过噻吨酮敏化溶液态[2 + 2]光聚合制备结构明确、结构复杂的truxinate环丁烷聚合物。具有不同电子密度和结构的单体可以以良好到优异的产率聚合，形成包含 42 种聚酯的库。内烯烃分离距离大于 5 Å 的单体很容易通过分子间 [2 + 2] 光环加成进行聚合，这与在烯烃距离较近的单体中观察到的分子内 [2 + 2] 光环加成相反。与间歇反应相比，连续流动反应器的使用减少了反应时间，增加了聚合物分子量，并降低了分散性。此外，在连续流动下，聚合反应的规模很容易超出间歇反应所能达到的范围。这一进步将基于曲辛酯环丁烷的聚酯，作为跨行业潜在用途的新材料，引​​领到了发展的最前沿，这种聚酯历来仅限于少数几个例子，并且仅限于研究规模的数量。