Preparation And Properties Of Conductive Polymer Hydrogels Formed By Photo-curing 3D Printing

At present,traditional conductive hydrogels had limited applications due to their low mechanical strength,single structure and unstable conductivity.Combining conductive hydrogels with 3D printing makes it possible to print complex human tissue structures.In this study,in order to form a conductive polymer hydrogel by digital light processing(DLP)3D printing,the printing resin of poly(2-hydroxyethyl acrylate-4-vinylbenzenesulfonic acid)(PHEA-PSS)hydrogel was prepared by one-pot method.Then,conductive polymer of poly(2-hydroxyethyl acrylate-4-vinylbenzenesulfonic acid)/poly 3,4-ethylenedioxythiophene(PHEAPSS/PEDOT)was prepared by photo-curing before in-situ polymerization.The hydrogels were characterized by FTIR,XRD,XPS,SEM,etc.The effects of ion concentration and conductive polymer content on the curing rate,mechanical properties,swelling properties and electrical properties of hydrogels were studied.PHEA-PSS hydrogel presented a three-dimensional porous network structure with high water absorption rate and high flexibility.The water absorption of pure PHEA-PSS hydrogel was 944 % at 24 h.The tensile strength was 0.29 MPa and the tensile strain was 311 % with 3 wt.% Ca Cl2.The curing time of each layer was only 25 s,which could meet the 3D printing in complex models such as thick structure or hollow structure.The PHEA-PSS/PEDOT hydrogel obtained by in-situ polymerization had a double network structure(DN)and the physical bond formed by iron ions,which improved the high mechanical strength and imparted certain self-healing property.The tensile strength was 4 MPa and the tensile strain was 173 % with 5 wt.% EDOT.PHEA-PSS/PEDOT hydrogel had good electrical conductivity(1.2 S/cm,12 wt.%),electric double layer capacitance characteristics and pressure responsiveness.It has great development in the field of capacitors and flexible sensors.It also provides experimental ideas for the preparation of other 3D-printable conductive polymer hydrogels.