Abstract:

Reversible crosslinked polymers, also known as covalent adaptable networks (CANs) based on vinylogous urethane were fabricated by condensation between bis-acetoacetate terminated polyether and tris (2-aminoethyl)amine. Three different bis-acetoacetate terminated polyethers with different repeat-units but similar molecular weight were synthesized. The effects of building block on the network structure, thermal and mechanical properties, and viscoelastic behaviors of CANs are examined. The results indicate that higher flexibility of the building blocks enables easier movement of chains in the network, leading to larger ductility, and lower modulus of the resulting CAN. In addition, the network topology rearrangement of the dynamic network is faster and the stress relaxation time is shorter at high temperature. Furthermore, the activation energies of vinylogous urethane CANs exhibit dual temperature response, which is distinguished from the CANs based other dynamic chemistries that are typically have a single linear relationship with temperature.

Key words: reversible crosslinked polymers, covalent adaptable networks, polymers, mechanical properties, polymer processing, polyether building block

摘要：

利用三种分子量相同但重复单元不同的双乙酰乙酸酯封端聚醚与三(2-氨基乙基)胺交联形成含乙烯基胺酯动态化学键的可逆交联聚合物，也称共价自适应网络。重点考察了构筑单元对动态交联网络的结构、热性能、力学性能及动态性能的影响。结果表明，当构筑单元链柔性更强时，网络中的分子链更容易运动，表现出较大的延展性及较低的模量。此外，在高温下动态网络的网络拓扑重排速度更快，应力松弛时间更短。不同于其他动态交换反应，乙烯基胺酯动态交换活化能由于交换机制的不同表现出明显的双温度响应。

关键词: 可逆交联聚合物, 共价自适应网络, 聚合物, 力学性能, 聚合物加工, 聚醚链段