Preparation And Performance Studies Of Multifunctional And High-strength Hydrogels

Hydrogels can be used as smart materials in the field of drug delivery,which improved the shortcomings of traditional drug delivery.The conductive hydrogel is used as a wearable device to detect human activities.And it has also attracted great attention in the fields of electronic skin and implantable devices.However,at present,the prepared smart-responsive hydrogels have disadvantages such as poor gel mechanical properties,monomers and cross-linking agents with biological toxicity,etc.,which limit the further application of the gel as a drug carrier.Similarly,conventional conductive gels cannot have both good biocompatibility and mechanical properties.In response to these shortcomings,this paper uses polyvinyl alcohol with good biocompatibility as the basic raw material to design two types of double network gels.(1)Polyvinyl alcohol(PVA),polyethyleneimine(PEI),and glutaraldehyde(GA)were used to synthesize intelligent dual-network hydrogels with pH-responsive properties.The first network was formed by PVA through freezing/thawing cycles.The second network was formed by chemical cross-linking of PEI and GA.The double network gel had good mechanical properties,and the tensile strength can reach 2.71 MPa.Under 50% deformation,the compressive strength of the gel can reach 4.13 MPa.The gel also had good elasticity and fatigue resistance.Sodium salicylate(SA)was used as a drug model,the drug release performance of the hydrogel under different pH conditions was studied.The results showed that the release of the gel is controllable.Under acidic conditions,the cumulative release rate was 65%.The cumulative release rate under alkaline conditions was 42%.The structure of the hydrogel was characterized by SEM.The results showed that as the content of PEI increases,the pore size of the hydrogel gradually decreases.(2)A cationic double-network hydrogel named polyvinyl alcohol/polyacrylamide/ poly carboxybetaine ester(PVA/PAM/PCBMAE)was prepared by free radical polymerization and physical cross-linking method,which had good electrical conductivity,antibacterial properties,anti-protein adsorption and mechanical properties.The cationic polymer formed a conductive path in the hydrogel network,so that the gel had good conductivity.With the increase of carboxybetaine eater(CBMAE),the conductivity gradually increases,can up to 0.25 S/m.As a sensor,hydrogel could respond quickly to strains such as stretching and bending.The tensile strength of the gel could reach 1.05 MPa,and the elongation at break was 474.31%.In addition,the hydrogel showed excellent antibacterial properties against Escherichia coli(E.coli),the antibacterial rate can reach up to 99%.After hydrolysis,the hydrogel showed stable anti-protein adsorption performance.This gel had potential application in the field of dressing and electronic skin.