Fabrication of Poly(acrylic acid)/Boron Nitride Composite Hydrogels with Excellent Mechanical Properties and Rapid Self-Healing Through Hierarchically Physical Interactions

Shishan Xue,Yuanpeng Wu,Dan Liu,Weiwei Lei,Tao Zhang,Meiling Guo

doi:10.1186/s11671-018-2800-2

Abstract

Many living tissues possess excellent mechanical properties and self-healing ability. To mimic these living tissues, a series of novel composite hydrogels, poly(acrylic acid)/surface-modified boron nitride nanosheets (PAA/BNNS-NH2) were fabricated simply through hierarchically physical interactions: molecular-scale metal coordination interaction between –COOH of PAA and Fe3+ and nanoscale H-bond between –COOH of PAA and –NH2 of BNNS-NH2. The composite hydrogels exhibit both excellent mechanical properties (including enhanced fracture stress, elongation, toughness, Young’s modulus, and dissipated energy) and rapid healing ability without any external stimulus. Especially, the B0.5P70 (the hydrogel with BNNS concentration of 0.5 mg mL− 1, the water content of 70 wt%) exhibits a fracture stress of ~ 1311 kPa and toughness of ~ 4.7 MJ m− 3, almost ~ 3 times and ~ 8 times to B0P70, respectively. The excellent properties, combined with the simple preparation method, endow these composite hydrogels with potential applications.

Highlights

Hydrogels with three-dimensional networks formed by covalent bonds and/or physical interactions crosslinking containing a large amount of water possess high hydrophilicity, water-holding capacity and unexceptional biocompatibility [1–4], enabling to be one of the most popular biomaterials
The as-formed poly(acrylic acid) (PAA) macromolecular chains were crosslinked by hierarchically physical interactions: metal coordination interaction between carboxyls (–COOH) of the PAA and Fe3+ in molecular scale, and hydrogen bond interaction between –COOH of the PAA and –NH2 of BNNS-NH2 in nanoscale, resulting in the formation of three-dimensional networks (Scheme 1)
The two different types of physical interactions within the PAA/BNNS-NH2 composite hydrogels were revealed by Fourier-transform infrared (FTIR) spectroscopy firstly

Summary

Introduction

Hydrogels with three-dimensional networks formed by covalent bonds and/or physical interactions crosslinking containing a large amount of water possess high hydrophilicity, water-holding capacity and unexceptional biocompatibility [1–4], enabling to be one of the most popular biomaterials. The novel composite hydrogels are fabricated from poly(acrylic acid) (PAA) and amino groups surface-modified boron nitride nanosheet (BNNS-NH2) through hierarchically physical interactions: molecular-scale metal coordination interaction between –COOH of PAA and ferric ion (Fe3+) and nanoscale H-bond between –COOH and BNNS-NH2 were reported.

Results

Conclusion