基于动态Mg^(2+)-吲哚的可修复可回收聚六氢三嗪薄膜的制备及性能

Preparation and Properties of Repairable and Recyclable Polyhexahydrotriazine Films Based on Dynamic Mg^(2+)-Indole Interactions

以色胺(Tryp)、聚(丙二醇)双(2-氨基丙醚)(D-400)和多聚甲醛为原料,简单共聚制备一系列吲哚基聚六氢三嗪(IN-PHT)聚合物薄膜材料,将聚合物薄膜用MgCl_(2)水溶液浸泡后烘干,得到Mg^(2+)-吲哚动态交联的聚六氢三嗪(Mg-IN-PHT)薄膜材料。元素分布图证实,Mg^(2+)在聚合物Mg-IN-PHT中存在且分布均匀。利用理论计算模拟、紫外可见吸收光谱法、荧光光谱法等手段证明了Mg-IN-PHT薄膜中Mg^(2+)与吲哚基团间形成了阳离子-π相互作用。通过循环拉伸测试表征了Mg-IN-PHT薄膜的力学性能,测试结果表明,Mg-IN-PHT薄膜具有较强的拉伸强度(16.1 MPa)和韧性(206.2%),明显高于IN-PHT薄膜(11.0 MPa,117.0%)。一方面,阳离子-π动态交联增大了聚合物网络中的交联密度,从而增强了薄膜的强度;另一方面,柔性聚合物网络受到外部刺激时易发生分子链的滑移,“点-面”阳离子-π相互作用可以更容易地形成和解除,能量耗散效果较好,从而提高了材料的韧性。同时研究了薄膜材料的热稳定性变化,结果表明,Mg-IN-PHT薄膜热分解温度(280℃)和玻璃化转变温度T_(g)(-10℃)均高于IN-PHT薄膜的热分解温度(234℃)和T_(g)(-16℃)。另外,动态的“点-面”阳离子-π相互作用赋予了Mg-IN-PHT膜优异的可修复和可回收性能。

A series of indole-based poly(hexahydrozine)(IN-PHT)flexible film materials were prepared by simple copolymerization of tryptamine(Tryp),poly(propylene glycol)bis(2-aminopropyl ether)(D 400)and paraformaldehyde,and the films were soaked in MgCl_(2) solution to prepare the Mg-poly(hexahydrozine)(Mg-IN-PHT)films crosslinked by Mg^(2+)-indole interaction.The uniform distribution of Mg^(2+)in Mg-IN-PHT was confirmed by EDS.The formation of cationπinteraction between Mg^(2+) and indole was demonstrated by UV,RF and theoretical calculation.The mechanical properties of Mg-IN-PHT films were characterized by cyclic tensile test.The results indicate that Mg-IN-PHT films have the stronger tensile strength(16.1 MPa)and toughness(206.2%),which are significantly higher than IN-PHT films(11.0 MPa,117.0%).On the one hand,cationπcross-linking increases the cross-linking density,thus enhancing the strength of film;on the other hand,the molecular chains of flexible polymer network slip easily when it was externally stimulated.So that the"point-surface"cationπinteractions could be formed and released more easily,and the energy dissipation effect is better,thus the toughness of film is improved.In addition,the thermal stability of Mg-IN-PHT was also investigated.The results indicate that the thermal decomposition temperature(280℃)and T_(g)(-10℃)of Mg-IN-PHT films are higher than those of IN-PHT films(234℃)and(-16℃).Finally,the dynamic“point-surface”cationπinteraction endows Mg-IN-PHT films with excellent self-healing and recycling abilities.