Role of Organic Phosphates and Phosphonates in Catalyzing Dynamic Exchange Reactions in Thiol-Click Vitrimers,Macromolecular Chemistry and Physics

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Role of Organic Phosphates and Phosphonates in Catalyzing Dynamic Exchange Reactions in Thiol-Click Vitrimers
Macromolecular Chemistry and Physics ( IF 2.5 ) Pub Date : 2021-04-14 , DOI: 10.1002/macp.202100072
Khadijeh Moazzen ₁ , Elisabeth Rossegger ₁ , Walter Alabiso ₁ , Usman Shaukat ₁ , Sandra Schlögl ₁

Affiliation

Owing to their strong Brønsted acidity, organic phosphates and phosphonates are able to catalyze dynamic transesterification reactions in hydroxyl ester networks. Compared to commonly used transesterification catalysts, they are highly soluble in a wide range of acrylate monomers and neither affect cure kinetics nor shelf-life of photocurable acrylate and thiol-acrylate resins. Additionally, they promote fast stress relaxation and, by using derivatives with functional groups, are covalently incorporated within the photopolymer network. These salient features make organic phosphates and phosphonates ideal catalysts for the design and processing of photoreactive vitrimers. Herein, the catalytic activity of selected methacrylate-functional phosphates and vinyl-functional phosphonates on dynamic transesterifications are studied comprehensively. They are incorporated in a thiol-acrylate photopolymer providing functional –OH and ester moieties. Cure kinetics and thermomechanical properties are not significantly affected by the structure and functionality of the catalyst. In contrast, time-dependent stress relaxation measurements show that relaxation time and activation energy correlate well with the logarithmic acid dissociation constants of the Brønsted acids. The better understanding of the role of organic phosphates and phosphonates expands the scope of transesterification catalysts and is particularly interesting for the design of photoreactive vitrimers, which can be additively manufactured by using vat polymerization techniques.

中文翻译：

有机磷酸盐和膦酸盐在催化硫醇点击玻璃体动态交换反应中的作用

由于其强布朗斯台德酸度，有机磷酸盐和膦酸盐能够催化羟基酯网络中的动态酯交换反应。与常用的酯交换催化剂相比，它们在广泛的丙烯酸酯单体中高度溶解，既不影响固化动力学，也不影响光固化丙烯酸酯和硫醇丙烯酸酯树脂的保质期。此外，它们促进快速应力松弛，并且通过使用具有官能团的衍生物，共价结合在光聚合物网络中。这些显着特征使有机磷酸盐和膦酸盐成为设计和加工光反应性玻璃体的理想催化剂。在此，综合研究了选定的甲基丙烯酸酯官能磷酸盐和乙烯基官能膦酸盐对动态酯交换的催化活性。它们被结合在提供功能性-OH 和酯部分的硫醇-丙烯酸酯光聚合物中。固化动力学和热机械性能不受催化剂结构和功能的显着影响。相比之下，随时间变化的应力松弛测量表明，松弛时间和活化能与布朗斯台德酸的对数酸解离常数密切相关。对有机磷酸酯和膦酸酯作用的更好理解扩展了酯交换催化剂的范围，并且对于光反应性玻璃体的设计特别有趣，它可以通过使用还原聚合技术进行增材制造。固化动力学和热机械性能不受催化剂结构和功能的显着影响。相比之下，随时间变化的应力松弛测量表明，松弛时间和活化能与布朗斯台德酸的对数酸解离常数密切相关。对有机磷酸酯和膦酸酯作用的更好理解扩展了酯交换催化剂的范围，并且对于光反应性玻璃体的设计特别有趣，它可以通过使用还原聚合技术进行增材制造。固化动力学和热机械性能不受催化剂结构和功能的显着影响。相比之下，随时间变化的应力松弛测量表明，松弛时间和活化能与布朗斯台德酸的对数酸解离常数密切相关。对有机磷酸酯和膦酸酯作用的更好理解扩展了酯交换催化剂的范围，并且对于光反应性玻璃体的设计特别有趣，它可以通过使用还原聚合技术进行增材制造。

更新日期：2021-06-21

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