The interfacial behavior of fiber-reinforced hydrogels with interphases: Experimental analysis, theoretical modeling and numerical simulation

Facing the drawbacks of traditional synthetic hydrogels, fiber-reinforced hydrogels are paid more attention due to their advantages such as high strength and fracture toughness, superior fatigue resistance and so on. However, the poor interfacial behavior of fiber-reinforced hydrogels hinders their blooming applications in flexible electronics, biochemistry, soft robotics, etc. Through existing works have dealt with direct bonding between fibers and the matrix, obvious shortcomings occur when the material mismatch is rather serious. Herein, a strategy of introducing interphases to improve the interfacial behavior of fiber-reinforced hydrogels is proposed. The interfacial response of fiber-reinforced hydrogels under single-fiber pull-out loads is comprehensively analyzed through experimental research, theoretical analysis and numerical simulation. It is found that fiber-reinforced hydrogels with interphases exhibit superior interfacial performance, and the corresponding interfacial failures can be effectively avoided due to the significant reduction of interfacial shear stress by up to 80 % and the increase of interfacial strength. What is more, the interfacial behavior of fiber-reinforced hydrogels with interphases can be well improved by tuning various material and geometric factors. These results should be helpful not only for the design of fiber-reinforced hydrogels, but also for the enhancement of knowledge of interfacial mechanics.