A facile approach for polymer hydrogels with enhanced strength, self−healing and multi−responsive shape memory properties

To improve the mechanical strength and realize more functionality of self−healing hydrogels in a cost−effective way, commercially available poly(vinyl alcohol) (PVA), borax and carboxyl methyl cellulose (CMC) were used in this work to prepare polymer hydrogels in one pot. The results show that the as−prepared hydrogels have enhancing strength, self−healing and multi−responsive shape memory properties. The rigid ring of CMC and the cross−linked networks formed by borate ester bonds and hydrogen bonds from PVA, CMC and borax can enhance the strength of the hydrogels, when the mass ratio of PVA/borax/CMC is 10:6:3, the tensile stress can reach up to 0.72 MPa. Borate ester bonds and hydrogen bonds can endow the hydrogels with good self−healing capability, the best self−healing efficiency can reach up to 83%. Additionally, since borate ester bonds are response to pH, and CMC is sensitive to Al3+ and Fe3+, shape memory properties of the hydrogels can be realized by controlling pH, and metal ions.