Vinylogous Urea—Urethane Vitrimers: Accelerating and Inhibiting Network Dynamics through Hydrogen Bonding
Vinylogous Urea—Urethane Vitrimers: Accelerating and Inhibiting Network Dynamics through Hydrogen Bonding
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乙烯基尿素 – 聚氨酯 Vitrimers：通过氢键加速和抑制网络动力学
DOI：
10.1002/anie.202318412
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发表时间：
2024
期刊：
影响因子：
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通讯作者：
Du Prez, Filip E.
中科院分区：
文献类型：
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作者：
Engelen, Stéphanie;Dolinski, Neil D.;Chen, Chuqiao;Ghimire, Elina;Lindberg, Charlie A.;Crolais, Alex E.;Nitta, Natsumi;Winne, Johan M.;Rowan, Stuart J.;Du Prez, Filip E.
基于乙烯基氨基甲酸酯(Vuo)的聚合物网络被广泛用作无催化剂玻璃体，在高温下表现出快速的共价键交换。在溶液中，乙烯基脲(VUN)的键交换速度比VUN快得多，而且在室温下是高度动态的。然而，在它们各自的动态聚合物网络中没有观察到这种反应性的差异，因为这里制备的具有非常相似的大分子结构的VUO和VUN玻璃体表现出类似的应力松弛和蠕变行为。然而，通过在同一网络中使用VUO和VUNlink的混合物，动态反应可以加速一个数量级。这一结果可以用分子间氢键效应来解释，这在VUO玻璃体中是不存在的，但对于VUO中的尿素部分是非常显著的。在低浓度的VUN下，这些氢键作为共价键交换的催化剂，而在高浓度时，它们提供了一个普遍存在的非共价相互作用的尿素-氨酯(VU)网络，导致相分离并抑制高分子链的动力学。这为动态聚合物材料提供了一个直观的设计原则，同时显示了超分子和动态共价聚合物网络可能的相加和协同效应。
Vinylogous urethane (VUO) based polymer networks are widely used as catalyst‐free vitrimers that show rapid covalent bond exchange at elevated temperatures. In solution, vinylogous ureas (VUN) undergo much faster bond exchange than VUOand are highly dynamic at room temperature. However, this difference in reactivity is not observed in their respective dynamic polymer networks, as VUOand VUNvitrimers prepared herein with very similar macromolecular architectures show comparable stress relaxation and creep behavior. However, by using mixtures of VUOand VUNlinkages within the same network, the dynamic reactions can be accelerated by an order of magnitude. The results can be rationalized by the effect of intermolecular hydrogen bonding, which is absent in VUOvitrimers, but is very pronounced for vinylogous urea moieties. At low concentrations of VUN, these hydrogen bonds act as catalysts for covalent bond exchange, while at high concentration, they provide a pervasive vinylogous urea ‐ urethane (VU) network of strong non‐covalent interactions, giving rise to phase separation and inhibiting polymer chain dynamics. This offers a straightforward design principle for dynamic polymer materials, showing at the same time the possible additive and synergistic effects of supramolecular and dynamic covalent polymer networks.