Yuan Dian, Delpierre Sébastien, Ke Kai, Raquez Jean-Marie, Dubois Philippe, Manas-Zloczower Ica
Department of Macromolecular Science and Engineering , Case Western Reserve University , Cleveland , Ohio 44106 , United States.
Laboratory of Polymeric and Composite Materials (LPCM), Center of Innovation and Research in Materials and Polymers (CIRMAP) , University of Mons , Place du Parc 23 , 7000 Mons , Belgium.
ACS Appl Mater Interfaces. 2019 May 15;11(19):17853-17862. doi: 10.1021/acsami.9b04249. Epub 2019 Apr 30.
As dynamic cross-linking networks are intrinsically weaker than permanent covalent networks, it is a big challenge to obtain a stiff self-healing polymer using reversible networks. Inspired by the self-healable and mechanically adaptive nature of sea cucumber, we design a water-responsive self-healing polymer system with reversible and permanent covalent networks by cross-linking poly(propylene glycol) with boroxine and epoxy. This double cross-linked structure is self-healing due to the boroxine reversible network as well as showing a room-temperature tensile modulus of 1059 MPa and a tensile stress of 37 MPa, on a par with classic thermosets. The dynamic boroxine bonds provide the self-healing response and enable up to 80% recovery in modulus and tensile strength upon water contact. The system shows superior adhesion to metal substrates by comparison with the commercial epoxy-based structural adhesive. Besides, this system can change modulus from a stiff thermoset to soft rubber (by a factor of 150) upon water stimulus, enabling potential applications of either direct or transform printing for micro/nanofabrication. Moreover, by incorporating conductive nanofillers, it becomes feasible to fabricate self-healing and versatile strain/stress sensors based on a single thermoset, with potential applications in wearable electronics for human healthcare.
由于动态交联网络本质上比永久性共价网络更弱，因此使用可逆网络获得坚硬的自修复聚合物是一项巨大的挑战。受海参自修复和机械适应性的启发，我们通过将聚丙二醇与硼氧烷和环氧树脂交联，设计了一种具有可逆和永久性共价网络的水响应自修复聚合物体系。这种双重交联结构由于硼氧烷可逆网络而具有自修复能力，并且在室温下的拉伸模量为1059 MPa，拉伸应力为37 MPa，与经典热固性材料相当。动态硼氧烷键提供自修复响应，遇水后模量和拉伸强度可恢复高达80%。与商业环氧基结构胶粘剂相比，该体系对金属基材具有优异的粘附性。此外，该体系在水刺激下可将模量从坚硬的热固性材料转变为柔软的橡胶（变化因子为150），从而实现微纳制造中直接或变换打印的潜在应用。此外，通过加入导电纳米填料，基于单一热固性材料制造自修复和多功能应变/应力传感器变得可行，在人类医疗保健的可穿戴电子产品中具有潜在应用。
