Preparation And Properties Research Of Functional Rapid Self-healing Hydrogels

Hydrogel is a kind of polymer material with unique three-dimensional network structure.Due to its good biocompatibility,sensitivity to the environment,abundant sources and low price,hydrogel has become the focus of scholars'research in recent years.And it has been widely used in many fields such as medical treatment,chemical engineering and pharmaceutical industry.However,the traditional hydrogels are inevitably damaged irreversibly in the application process,and the hydrogels cannot be used after being damaged.In addition,the polymer matrix of the traditional hydrogels also leads to the fact that most of the hydrogels cannot conduct electricity,which greatly limits the application of hydrogels in flexible electronic devices.In addition to polymer matrix external water as another important component of hydrogel also has the disadvantage of losing elasticity at low temperature,which also limits the application of hydrogel.In view of the disadvantages of the traditional hydrogels mentioned above,we improved the hydrogels to prepare a kind of fast self-healing hydrogels with cold resistance and conductive characteristics.In order to prepare rapid self-healing hydrogels,sodium alginate was modified by grafting 3-Aminophenylboronic acid onto sodium alginate.Based on the self-healing mechanism of dynamic chemical bond,a rapid self-healing hydrogel was prepared by PVA solution and modified sodium alginate solution.After being damaged,the hydrogel could self-heal at about 30 s.With the increase of sodium alginate content,the mechanical properties of the hydrogel also improved slightly,the elastic modulus of hydrogel increased from 3.0×10~3 Pa to 9.8×10~3 Pa.To give the hydrogel electrical conductivity,NaCl was added to the solvent of the hydrogel.Since the hydrogel contains a large amount of water,Na~+and Cl~-will be dissociated in the water after NaCl is added,and the free movement of ions in the water makes the hydrogel have the conductivity.When the amount of NaCl was 8.75 mg/mL,the conductivity of hydrogel was 3.83 S/m.In this paper,the application of hydrogel in sensors is simulated.The body movement is monitored by the rate of change of resistance caused by hydrogel deformation.In addition,we can write on capacitive screens with hydrogel.In order to improve the cold resistance of the hydrogel,glycerol was added into the solvent of the hydrogel,and the cold resistance of the hydrogel was also improved with the increase of the amount of glycerol added.But too much glycerol can cause PVA powder to not dissolve completely.Moreover,with the increase of glycerol content,the improvement of cold tolerance is less and less obvious.Therefore,when the glycerol content is 25%,the comprehensive performance of hydrogel is the best,and the lowest cold tolerance temperature of hydrogel is-23°C.