One-Pot Assembly of Microfibrillated Cellulose Reinforced PVA-Borax Hydrogels with Self-Healing and pH-Responsive Properties

A facile, environmentally benign approach has been developed for the preparation of dynamic, multiresponsive, and self-healing hydrogels from inexpensive bamboo pulp, poly(vinyl alcohol) (PVA), and borax. The microfibrillated cellulose (MFC) reinforced PVA-borax hydrogels were produced through a one-pot route in conjunction with ball milling and physical blending in tandem in aqueous medium. In this way, MFC particles could be efficiently generated and well-dispersed in a polymer matrix, and they have been verified by scanning electron microscopy. The theology analysis indicated a close relationship between the mechanical strength and the MFC loading and ball milling time. Due to the dynamic equilibrium of the didiol-borax linkages and the reinforcement of MFC fibers, the hydrogels showed enhanced self-healing behavior and mechanical stiffness, which was also supported by rheology analyses. In addition, the hydrogels were found to be sensitive to the pH value. The hydrogels present a solvent or gel state with the change of pH value, and this sol-gel transfer can be repeated while maintaining the shape, further demonstrating the dynamic reversible behavior of the hydrogels.