Wang Tong, Chen Yixuan, Chen Boran, Suazo Mathew J, Purwanto Nathan S, Torkelson John M
Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208 United States.
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 United States.
ACS Macro Lett. 2024 Sep 17;13(9):1147-1155. doi: 10.1021/acsmacrolett.4c00391. Epub 2024 Aug 16.
We synthesized covalent adaptable networks (CANs) made from chain-growth comonomers using nonisocyanate thiourethane chemistry. We derivatized glycidyl methacrylate with cyclic dithiocarbonate (GMA-DTC), did a free-radical polymerization of -hexyl methacrylate with GMA-DTC to obtain a statistical copolymer with 8 mol % GMA-DTC, and cross-linked it with difunctional amine. The dynamic covalent thionourethane and disulfide bonds lead to CAN reprocessability with full recovery of the cross-link density; the temperature dependence of the rubbery plateau modulus indicates that associative character dominates the dynamic response. The CAN exhibits complete self-healing at 110 °C with tensile property recovery and excellent creep resistance at 90-100 °C. Stress relaxation at 140-170 °C reveals an activation energy of 105 ± 6 kJ/mol, equal to the activation energy () of the CAN poly(-hexyl methacrylate) backbone α-relaxation. We hypothesize that CANs with exclusively or predominantly associative dynamics have their stress-relaxation defined by the α-relaxation . This hypothesis is supported by stress relaxation studies on a similar poly(-lauryl methacrylate)-based CAN.
我们使用非异氰酸酯硫脲化学方法合成了由链增长共聚单体制成的共价自适应网络（CANs）。我们用环状二硫代碳酸酯对甲基丙烯酸缩水甘油酯进行衍生化（GMA-DTC），将甲基丙烯酸己酯与GMA-DTC进行自由基聚合，以获得含8摩尔% GMA-DTC的统计共聚物，并用双官能胺对其进行交联。动态共价硫脲和二硫键使CAN具有可再加工性，交联密度可完全恢复；橡胶态平台模量的温度依赖性表明，缔合特性主导了动态响应。该CAN在110°C时表现出完全自愈能力，拉伸性能得以恢复，在90 - 100°C时具有优异的抗蠕变性。在140 - 170°C下的应力松弛显示活化能为105±6 kJ/mol，与CAN聚（甲基丙烯酸己酯）主链α松弛的活化能（）相等。我们假设，具有完全或主要缔合动力学的CANs，其应力松弛由α松弛定义。对类似的基于聚（甲基丙烯酸月桂酯）的CAN进行的应力松弛研究支持了这一假设。
