Preparation And Functional Study Of Polyvinyl Alcohol/keratin Composite Hydroge

As a polymer with three-dimensional network structure,polyvinyl alcohol（PVA）hydrogel is rich in water content,excellent in lubricity and biocompatibility,and has good elasticity and large tensile force.Can be applied to industrial fields such as dye cleaning and waste adsorption,medical fields such as medical dressings,tissue engineering and drug carriers,and electronic fields such as wearable devices and flexible sensors.In this paper,wool keratin（KE）,aluminum ion(Al³⁺)and carbon nanotubes（CNT）were introduced into PVA to prepare composite hydrogels with different functions,and their properties were studied.The main contents are as follows:（1）Firstly,wool keratin（KE）with abundant intermolecular and intramolecular forces was obtained by reducing waste wool.Self-made wool keratin（KE）was added into polyvinyl alcohol（PVA）solution to prepare PVA/KE composite hydrogel with good mechanical properties.The network pore structure changed with the change of PVA and KE content,and the hydrogel showed different mechanical properties repairing ability.The pore size is positively correlated with the KE content,and the pore size（1.1～2.1um）with the mass ratio of 6:4 is the largest,at which the water content and porosity reach 89.1%and 85.3%.When the mass ratio is 9:1,the hydrogel has the strongest tensile properties,with the elongation at break of 334.1%and the breaking strength of 9.08MPa;The swelling rate is also up to 42%,and the internal network of PVA/KE hydrogel can repair the structural changes formed during cyclic stretching.（2）Then,PVA/KE/Al³⁺composite hydrogels with good self-healing properties were prepared by adding different concentrations of Al Cl3 into PVA/KE hydrogels to chemically cross-link PVA and keratin,and constructing a double-network structure with hydrogen bond network and Al³⁺ion complex network.The similarities and differences of mechanical properties and self-healing properties of composite hydrogels with different contents of crosslinking agents were analyzed.With the increase of crosslinking agent,the surface of hydrogel changed from rough to smooth,and a three-dimensional porous structure with pore size range changed from large to small and pore structure changed from open to tight was formed inside.When the Al³⁺concentration in the hydrogel is 2%,the breaking strength is8.28MPa and the breaking elongation is 169.2%,which shows the best mechanical properties.The changes of self-healing and fatigue resistance of hydrogel show consistency.When the healing time is 12h and the concentration of crosslinking agent is 2%,the healing efficiency is the best,which can reach 89.4%.（3）Finally,different content of CNT was added to PVA/KE hydrogel,and the internal network of hydrogen bond structure and carbon tube structure was constructed,and the PVA/KE/CNT composite hydrogel with good conductivity was prepared.The differences of internal functions and conductivity of hydrogels with different concentrations of CNT were also studied.The addition of CNT makes the internal structure of hydrogel more compact,and the stress and strain also increase,reaching a maximum of 2.87MPa;when 5%CNT is added.The healing test of hydrogel showed that the healing effect was the best after 12 hours,and the healing efficiency was inversely proportional to CNT concentration.The electrical conductivity detection shows that the electrical conductivity increases with the increase of the concentration of carbon nanotubes,and reaches the maximum value of 2.56 S·m-1 when the concentration of carbon nanotubes is 5%.In addition,the composite hydrogel added with CNT can monitor the changes of human movement and physiological electrical signals,such as neck,wrist,fingers and vocal cords,and can be applied to smart wearable and electronic skin.