提高动态共价键密度设计高动态性能酯交联橡胶,Polymer Chemistry

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提高动态共价键密度设计高动态性能酯交联橡胶
Polymer Chemistry ( IF 4.1 ) Pub Date : 2022-11-14 , DOI: 10.1039/d2py01165d
Li Yang ₁ , Luji Li ₁ , Lihua Fu ₁ , Baofeng Lin ₁ , Yueqiong Wang ₂ , Chuanhui Xu _{1,

2}

Affiliation

动态共价键（DCBs）实现了聚合物网络的拓扑重排，为橡胶材料的可持续发展提供了契机。不幸的是，在大多数情况下，橡胶链的拓扑约束（缠结）和 DCB 的非理想分布（即低密度）导致网络的拓扑重排动力学缓慢，从而导致橡胶的回收或修复性能差。增加网络中 DCB 的密度（特别是具有小空间位阻的）以加速其动态性能似乎对于链段动力学差和主链空间位阻大的橡胶具有重要意义，例如羧基苯乙烯丁二烯橡胶（XSBR），解决或至少改善上述问题。在本文中，通过严格控制交联密度、拓扑结构、催化剂和羟基浓度，精心设计了两种具有相似网络结构但酯键密度不同的橡胶玻璃体（XSBRZA 和 XSBRZO），以公平地评估 DCBs 对性能的影响。橡胶的动态性能。由于酯键密度的增加，包括具有较小空间位阻的琥珀酸酯，增加了酯交换的可能性，与 XSBRZO 相比，XSBRZA 表现出显着更短的弛豫时间和更低的弛豫活化能。此外，XSBRZA 显着降低了高温下发生的副反应产生的负面影响，有利于橡胶玻璃体的多次再加工。这项工作强调了 DCB 分布（密度）对橡胶 vitrimer 动态特性的重要性。

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Design of ester crosslinked rubber with high dynamic properties by increasing dynamic covalent bond density

Dynamic covalent bonds (DCBs) realize the topological rearrangement of polymer networks, which provides an opportunity for the sustainable development of rubber materials. Unfortunately, in most cases, the topological constraints (entanglements) of rubber chains and the nonideal distribution (namely the low density) of DCBs result in slow topological rearrangement dynamics of networks, which leads to poor recycling or healing performances of the rubbers. Increasing the density of DCBs (especially with small steric hindrance) in networks to accelerate their dynamic properties seems to be of great significance for rubbers with poor segment dynamics and large steric hindrance of the main chains, e.g. carboxylic styrene butadiene rubber (XSBR), to solve or at least ameliorate the above issue. In this paper, two rubber vitrimers (XSBRZA and XSBRZO) with a similar network structure but different densities of ester bonds were carefully designed by strictly controlling their crosslinking density, topological structure, catalyst and hydroxyl group concentration to fairly evaluate the effect of DCBs on the dynamic properties of rubbers. Since the increased density of ester bonds, which include the ester succinate with smaller steric hindrance, increases the probability of transesterification, XSBRZA exhibits a significantly shorter relaxation time and lower relaxation activation energy compared with XSBRZO. Besides, negative effects originating from the side reactions occurring at high temperature are significantly reduced in XSBRZA, which is conducive to the multiple reprocessing of rubber vitrimers. This work emphasizes the importance of DCB distribution (density) to the dynamic properties of rubber vitrimers.

更新日期：2022-11-14

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