Preparation And Representation Of Two-Component Self-Healing Smart Hydrogel

Smart hydrogel could change their properties such as volume,shape,strength,etc.,according to external stimuli.However,the single-component materials had many limitations in terms of preparations and applications.Therefore,the use of two-component materials to prepare smart gel materials was the first choice for most researchers.This method could be widely used to prepare gel materials and devices such as drug delivery,artificial muscles,exercisers,biosensors,and bio-inks.As far as the current research,most researchers only prepared materials by simply blending two components,thus developing more diversified preparation methods and designing multifunctional gel materials would be one of the directions of future development.Moreover,the self-healing properties of materials could effectively repair the damage when defects occurred,and prolong the lifetime.Therefore,the research of self-repairing properties of materials was also significant.Here,after fully considered the characteristics of the two components and their applications,we had fabricated the functional two-component polymer gels with completely different means.A pH responsive dynamic covalent crosslinked self-healing hydrogel with tunable mechanical properties was developed by in-situ blending two conponents with a double barrel syringe.On the other hand,the thermal-responsive adhesive anisotropic organic hydrogel with frost resistance and long-term stability was prepared by using two fully miscible solvent with huge difference in density and intermolecular force.The unique adhesive abilities and deformable abilities made it a promising material for actuators or surface dressing.The following was the specific research content of this article:(1)In the introduction,we briefly introduced the types of stimuli-responsive gels and the self-healing mechanism.(2)In the second section,two components with four recognized polymer chains was synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.An acrylhydrazone cross-linked network and a boronate ester cross-linked network orthogonally were formed in-situ from a single double-barrel syringe administration to obtain a fully interpenetrating polymer network hydrogel.Since acrylhydrazone and boronate ester exchange at acidic and basic environment respectively,the hydrogel could self-heal effectively at either acidic or basic conditions.Moreover,the pH induced IPN to semi-IPN reversible transition,endowing the hydrogel with tunable pore structure and mechanical properties.We hoped this novel strategy would provide new opportunities in design and preparation of the printable hydrogels with tunable mechanical properties and self-healing abilities.(3)In the third section,we found H2O and glycerol would not immediately completely mixed and spontaneous phase separation with no shake,thus,we fabricated a H20/glycerol gel.Glycerol was a non-toxic solvent that could effectively increase the frost resistance of the material and reduce water evaporation.The only monomer we used here was N-hydroxyethyl acrylamide,which could double hydrogen bonding with each other in water and single hydrogen bonding with glycerol.Hence,even with no crosslinking agent,this material had quiet good strength.Besides,the adhesion of two surfaces had big difference due to the free hydroxyl in twophases.With increasing temperature,the mechanical properties would become poor,for the destroy of hydrogen bonding,and decreasing the temperature,the strength of the material would be restored.Thus,this anisotropic thermoplastic gel could self-heal.(4)Finally,we have made a systematic summary of the research work in this paper and looked into the future of the research.