Preparation And Properties Of Hydrophobic Association Structure Hydrogels Containing Lamellar Nanofillers

As one type of the most important intelligent materials,shape memory hydrogels(SMHs)have gathered considerable interest due to their promising applications.However,preparing SMHs with excellent mechanical properties still remains as a big challenge.In this study,a new type of SMHs with excellent mechanical strength is created.Hydrophobic association structure formed by N,N-dimethyl acrylamide(DMA:hydrophilic monomer),octadecyl acrylate(C18:hydrophobic monomer)and emulsifier gelatin and H-bonds network structures formed by the hydrogel molecular chain and clay enhances the mechanical strength of the hydrogels simultaneously.The main research contents are as follows:1.Poly(N,N-dimethylacrylamide-octadecyl acrylate)hydrogels were prepared with C18 of 0 mol%,1 mol%,2 mol%,and 3 mol%by radical copolymerization,FT-IR shows DMA and C18 copolymerizated.The article study the effect of the hydrophobic association structures formed by PDMA,PC 18 and gelatin on the physical properties of P(DMA-C18)hydrogels.The results shows that as the C18 content increases,the hydrophobic association structure increases and the mechanical strength increases,the tensile strength and elongation at break of P(DMA-C18)hydrogels reached the highest value when the C18 content was 3 mol%,while the glass transition temperature and swelling ratio of the hydrogels decreased with C18 increasing.2.Clay were added into P(DMA-C18)hydrogels,the quality scores of clay were 0 wt%,1 wt%,3 wt%,5 wt%respectively,the article study the effect of the content of clay on the mechanical properties of hydrogels.The results show that nanocomposite network structure increases with clay increasing,and the strength of P(DMA-C18)-clay hydrogels gradually increases,the tensile strength,elongation at break,and hardness of hydrogels all reach the highest value when the clay is 5 wt%,and the compressive strength of P(DMA-C18)-clay hydrogels reach 4 MPa at compressive strain is 90%.Degradation experiments showed that clay enhanced the stability of hydrogels and the complete structure still remained after degrading 30 days in PBS at 37 ℃.The effect of clay on other physical properties of P(DMA-C 18)-clay hydrogels were investigated.The results show that as clay increased,the glass transition temperature increases slightly;the swelling ratio decreased with the physical cross-linking points increase;shape memory tests show that hydrogels possess good shape memory performance that physical cross-linking points as a stationary phase,PC 18 side chain as a reversible phase;cytotoxicity test shows that the hydrogels have low toxicity and meet the requirements of practical application;the dispersion of clay in the dried hydrogels was explored using a transmission microscope,indicating that the inorganic filler was uniformly dispersed in the hydrogels.The tensile strength and compressive strength of the Ref-1 hydrogels showed that hydrogels without emulsifier gelatin possessed lower mechanical properties than other hydrogels.The main reason was that:gelatin used as emulsifier is an important part of hydrophobic association structures;gelatin can form considerable H-bonds with gelatin and PDMA molecular chains.3.Adding GO into P(DMA-C18)hydrogels,and the article mainly investigate the effect of GO with different content on the physical properties of P(DMA-C18)-GO hydrogels,including glass transition temperature,swelling properties,mechanical properties,degradation properties,shape memory properties,toxicity.The results show that the trend of properties of P(DMA-C18)-GO hydrogels is similar to the P(DMA-C 18)-clay hydrogels,but the mechanical strength of P(DMA-C 18)-GO hydrogels is higher than P(DMA-C18)-clay hydrogels.