仿蠕虫状聚吡咯基复合纤维的构建及应变不敏感导电性能研究

Construction and Strain-insensitive Performance of Worm-shaped Polypyrrole-based Composite Fiber with Elastic Wrinkles Structure

采用表面改性、原位聚合和可控牵伸整理技术在弹性聚氨酯表面构建蠕虫状水性聚氨酯@聚吡咯弹性褶皱,开发了一种同时具备高拉伸导电稳定性和较小滞后性的应变不敏感导电纤维.通过扫描电子显微镜、强力仪、红外光谱及系统源表等对纤维的微观形貌、表面成分、力学性能、应变不敏感性能以及循环稳定性等进行表征.结果表明:该蠕虫状应变不敏感导电纤维不仅表现出优异的应变不敏感行为(在300%应变下的ΔR/R_(0)=1.88),最高可承受1500%的应变,而且在加载卸载300%循环时表现出较小的滞后性(0.03)和长期耐用性(>1000个拉伸-释放循环),这种智能材料在高拉伸电子学领域具有广阔的应用前景.

Highly stretchable and durable conductors are significant for the development of wearable devices,robots,human-machine interfaces,and other artificial intelligence products.However,high stretchability and small hysteresis are difficult to be attained for conventional conductive fibers,restricting their applications as stretchable electronics.In this work,a worm-inspired strain-insensitive conductive fiber with both outstanding strain-insensitive performance and small hysteresis was developed by combining surface modification,interfacial polymerization and modified pre-strain finishing to construct aqueous polyurethane@polypyrrole elastic wrinkles on an elastic multifilament.The microscopic morphology,surface composition,mechanical performance,strain-insensitive properties and durability of the composite fibers were characterized by scanning electron microscope(SEM),electronic strength tester,infrared spectroscopy(FTIR)and SourceMeter.FTIR results suggested the successful attachment of DOPA and PPy coating.Thermogravimetric analysis(TGA)demonstrated that the loading capacity of PPy exhibited an obviously increasing trend from 1.49%of PU0@PPy fiber to 6.96%of PU300@PPy fiber,and they all exhibited excellent electrical conductivity fluctuating around 100 S·m^(−1).More importantly,such bionic stretchable conductive fiber wrapped with elastic wrinkles not only exhibited excellent strain-insensitive behavior(ΔR/R_(0)=1.88)up to 300%strain but also revealed small hysteresis(0.03)after a stretching-releasing cycle and long-term durability(>1000 stretching-releasing cycle),and it also exhibited a wonderful Q value(1.60)though it was in a state of high strain(300%)as compared to many recently reported stretchable conductors based on spirally structure,buckling structure,negative Poisson’s ratio structure and so on.Accordingly,it can be applied to monitor the human body where it would undergo large deformations,such as finger joints,wrist and elbow.In addition,the resistance change of PU300@PPy fiber still kept within an order of magnitude after experiencing 200 cycles of soaping and 1000 times of strong friction.In a word,such biomimetic strain-insensitive conductive fiber holds great potential in the fields of highly stretchable electronics.