Preparation And Characterization Of Tough Polyion Composite Hydrogels

Hydrogels,especially with strong and tough mechanical performances,have attracted extensive attention due to their promising applications such as structural biomaterial,implantable devices,smart sensors and actuators,etc.Inside of these tough hydrogels,polyion complex(PIC)hydrogels,formed by the charge attraction of opposite charged polymer chains,have received a unique researching interest because of their distinguished properties including tough,fatigue resistance,self-recovery,self-healing,rebuild/recycle and even anti-biofouling abilities.However,conventional preparing method with large amount of residual salt in the as-prepared hydrogel needs a long-time dialysis treatment and induces a large shrinkage in volume which causes a difficulty in maintaining the accurate shape of the mold.Both limit the applications of PIC hydrogels.Here,we reported a novel strategy for one-step fabrication of strong and tough PIC hydrogels without long time dialysis treatment and large shrinkage after polymerization.The main contents of this paper are as follows.(1)Strong and tough hydrogels and polyion complex hydrogels were briefly introduced.(2)The preparation of the hydrogels started from mixing a novel and cationic bicarbonate monomer MPTB(3-(methacryloylamino)propyltrimethylammonium bicarbonate)with a series of anionic polymers polyacids(PSSA,PAAc,PAMPS),and the counter ions bicarbonate and H+ reacted with each other to form gas carbon dioxide escaping from the system.The resultant salt-free catanionic prepolymerization solution was polymerized via UV irradiation and the tough PIC hydrogels was achieved immediately without further processes.From our experiments,the PIC hydrogels prepared by this novel strategy maintain the tough mechanical performances,self-recovery and self-healing properties discovered in conventional preparation.Furthermore,by using photomask,the hydrogel shows a possibility in photopatterning and 4D printing.(3)The new method for preparing PIC hydrogels was used to directly adjust the types and concentrations of different counter ions in the preparation process,and the effects of ion specific effects on the mechanical properties of hydrogels were studied.