Design,Preparation And Properties Of High Strength、Self-healing Nanocomposite Hydrogels

Hydrogel is a kind of soft material with three-dimensional network structure.It has many excellent properties such as high water content,biocompatibility,strong capacity of water absorption and water retention and high plasticity.So it is widely used in biological tissue engineering,sensor,commercial and other fields.In order to make the application of hydrogels more extensive,in recent years,more and more researches have made hydrogels functionalized,such as conductive hydrogels,injectable hydrogels and self-healing hydrogels.However,the development of functionalized hydrogels at this stage is confined to two aspects:1.The mechanical properties of hydrogels are poor.The hydrogel structure is easily destroyed due to external force,resulting in low safety 2.Hydrogel functionalization is more difficult or less functional.Therefore,preparation and design of a hydrogel with high mechanical properties and high functionality has great significance and good application prospects.Here we report a simple method to synthesize smart hydrogels with high mechanical properties and high functionality.The synthesis method is divided into two parts.The first part is introduce the dynamic coordination key in the hydrogel,so that the hydrogel has high mechanical properties and rapid and efficient healing ability.The second part adjusts the type of dynamic coordination key,so that the gel has excellent anisotropic properties.The conclusions are as follows:1.By introducing dynamic Au-SR bonds as healing and cross-linking agents into the hydrogel network,N-isopropylacrylamide as a temperature-sensitive monomer,KPS as initiator synthesis the gold particles nano-composite hydrogel.It has a uniform network structure so that it can reach 1MPa stress under external force and strain can reach 24.On the other hand,due to the excellent photothermal properties of the gold particles,hydrogels deliver rapid self-healing with optimal efficiency of nearly 96%under near-infrared irradiation in 1 min.2.Using the same method introducing dynamic Ag-SR bonds as healing and cross-linking agents into the hydrogel network,the modified silver particles as a cross-linking agent.Since the Ag-SR bond can be exchanged dynamically under both laser and acid-base conditions,the resulting hydrogel has the dual ability to induce self-healing.At the same time,because of the self-assembly of modified silver particles under UV irradiation phenomenon,was induced the gel’s internal structure become a layered structure,which made the gel possess excellent anisotropic properties.Subsequently,we conducted a series of investigations on the anisotropic mechanical properties,the self-healing conditions,and the swelling of the hydrogel.