Cross-linker control of vitrimer flow
Cross-linker control of vitrimer flow
复制标题
DOI：
10.1039/d0py00233j
复制
发表时间：
2020-09-07
影响因子：
4.6
通讯作者：
Kalow, Julia A.
中科院分区：
文献类型：
--
作者：
El-Zaatari, Bassil M.;Ishibashi, Jacob S. A.;Kalow, Julia A.
三聚体是一类共价自适应网络（CAN），通过缔合交换反应进行拓扑重构，使在高温下再加工。在这里，我们表明，交联剂的反应性是一个额外的设计参数，以调整应力松弛率在vitrimers。在计算活化能的指导下，我们制备了一系列具有不同反应活性的交联剂，用于PDMS硫酸盐中硫醇的共轭加成-消除。令人惊讶的是，尽管有很宽的应力松弛速率范围，我们观察到，散装材料的流动活化能是独立的交联剂结构。可以对不同的交联剂进行频率扫描的储能模量和损耗模量的叠加，表明相同的交换机制。我们表明，我们可以在一个单一的材料中混合不同的交联剂，以进一步调节应力松弛行为。
Vitrimers are a class of covalent adaptable networks (CANs) that undergo topology reconfiguration via associative exchange reactions, enabling reprocessing at elevated temperatures. Here, we show that cross-linker reactivity represents an additional design parameter to tune stress relaxation rates in vitrimers. Guided by calculated activation barriers, we prepared a series of cross-linkers with varying reactivity for the conjugate addition-elimination of thiols in a PDMS vitrimer. Surprisingly, despite a wide range of stress relaxation rates, we observe that the flow activation energy of the bulk material is independent of the cross-linker structure. Superposition of storage and loss moduli from frequency sweeps can be performed for different cross-linkers, indicating the same exchange mechanism. We show that we can mix different cross-linkers in a single material in order to further modulate the stress relaxation behavior.