Preparation And Characterization Of Hybrid Hydrogel Crosslinked By Functional Microsphere

As aggregations of polymer network and water,hydrogels are abundant in plant and animal tissues.Owing to their unique integration of solid and liquid,hydrogel are widely used in Biology and medicine.But as swollen polymer network in water,hydrogels are usually brittle and the mechanical properties are poor.Numerous researchers are working on the development of hydrogels with excellent mechanical properties.Therefore,it is necessary to prepared a hydrogel with excellent mechanical properties.At present,macromolecular microsphere polymer materials have attracted the attention of researchers and macromolecular microsphere hybrid crosslinked hydrogels generally have superior mechanical properties.In the paper,cationic polymethyl methacrylate nanospheres(CL)were first prepared.CL was synthesized by soap-free emulsion polymerization and mainly composed of MMA and MATMAC.The results of the ~1H NMR and FTIR tests indicated that the CL was successfully prepared by the experiment.The results of DLS,TEM and conductometric titration tests indicate that CL has a high surface charge density and good monodispersity.Through changing the experimental conditions,a series of CL with different particle sizes were prepared.The CL was self-assembled by vertical deposition.The SEM electron micrograph showed that the CL after self-assembly showed a close-packed compact structure,which further proved that CL has high surface charge density and excellent monodispersity.CL with different particle sizes were selected as dynamic cross-linking points of hydrophobic segments to prepare macromolecular microsphere cross-linked hybrid acrylamidehydrophobicallyassociatinghydrogel(P(AAm-co-HMA)-CL).The P(AAm-co-HMA)-CL hydrogel had excellent mechanical properties and the breaking strength and toughness could reach 1.33 MPa and 11.72 MJ m~-33 respectively,additionally,the hydrogel exhibited rapid self-healing properties and good fatigue resistance.The experiment explored the effect of microspheres and hydrophobic segments content on the mechanical properties of hydrogels.When the content of CL was 0.25 wt%and the content of HMA was 0.5 mol%,the hydrogel has an appropriate crosslink density and thus has excellent mechanical properties.The experiment also explored the effect of microsphere diameters on the mechanical properties of hydrogels.As a result,the CL having a particle diameter of 194 nm was more advantageous for the hydrophobic segment to be entangled on the surface.Therefore,the microspheres with smaller size as dynamic cross-linking center in hydrogels had the superior mechanical properties and self-healing properties.