Preparation And Application Of The Polyvinyl Alcohol Self-healing Hydrogels

Hydrogels based on dynamic covalent bonds are different from traditional covalent crosslinked chemical hydrogels.Reversible dynamic covalent bond can endow hydrogels with many functions and self-healing property,making them exhibit great application prospects in medicine,electronics and other fields.In recent years,there are many reports on self-healing hydrogels using dynamic covalent bonds.However,most of the self-healing hydrogels are formed by dynamic interaction between macromolecules,forming a dynamic covalent bond.The healing time is longer and the efficiency is lower.Moreover,the route and method of preparation are complex,which greatly increases the preparation cost of hydrogels.In this paper,small molecule is choosed to cross-link polyvinyl alcohol(PVA).Synthesis of self-healing hydrogels based on multi dynamic covalent bonds is expected to greatly shorten healing time and improve self-healing efficiency.1.Study on the formation and self-healing property of dynamic covalent crosslinking network based on small molecule crosslinked PVA.Taking PVA as the main body of macromolecule,with 4-formyl benzene boronic acid(FPBA)and lysine(Lys)as crosslinking agent,a hydrogel network based on dynamic imine bond and dynamic benzene borate ester bond is formed.These two dynamic covalent bonds form a short chain with a certain length between macromolecular chains,which is beneficial to fast and efficient self-healing.The mechanical property,microstructure changes and self-healing property of the repair materials were evaluated by pH and healing time,and the best pH(9.5)value for self-healing performance and the shortest healing time(～3 min,self-healing efficiency 94%)for complete healing were obtained.2.Study on application of rapid self-healing hydrogel on sensor.The hydrogel prepared above is applied into strain sensors,and the self-healing is combined with the electrical conductivity and sensing properties of the materials.The effect of self-healing on the sensing performance is studied.The results show that the truncated material can basically restore its original sensing performance within 3 min(such as,when dinger bending 90°,ΔR/R0=12%),and it can be applied to the bending and stretching sensing of fingers and wrist,so as to effectively monitor the movement of human body.