Department of Organic and Macromolecular Chemistry, Polymer Chemistry Research Group and Laboratory for Organic Synthesis, Ghent University, Krijgslaan 281 S4-bis, Ghent B-9000, Belgium.
Matière Molle et Chimie, UMR 7167 CNRS-ESPCI, ESPCI ParisTech, 10 rue Vauquelin, Paris 75005, France.
Nat Commun. 2017 Mar 20;8:14857. doi: 10.1038/ncomms14857.
Vinylogous urethane based vitrimers are polymer networks that have the intrinsic property to undergo network rearrangements, stress relaxation and viscoelastic flow, mediated by rapid addition/elimination reactions of free chain end amines. Here we show that the covalent exchange kinetics significantly can be influenced by combination with various simple additives. As anticipated, the exchange reactions on network level can be further accelerated using either Brønsted or Lewis acid additives. Remarkably, however, a strong inhibitory effect is observed when a base is added to the polymer matrix. These effects have been mechanistically rationalized, guided by low-molecular weight kinetic model experiments. Thus, vitrimer elastomer materials can be rationally designed to display a wide range of viscoelastic properties.
基于乙烯基氨基甲酸酯的拟似弹性体是聚合物网络，具有通过快速加成/消除游离链末端伯胺的反应来进行网络重排、应力松弛和粘弹流的固有特性。在这里，我们表明，通过与各种简单添加剂结合，可以显著影响共价交换动力学。正如预期的那样，使用布朗斯特或路易斯酸添加剂可以进一步加速网络水平上的交换反应。然而，令人惊讶的是，当将碱添加到聚合物基体中时，观察到强烈的抑制作用。这些影响已经通过低分子量动力学模型实验得到了机械合理化。因此，可以合理设计拟似弹性体弹性体材料以显示出广泛的粘弹性性质。
