Preparation And Properties Of N,N Methylenebisacrylamide/Clay Crosslinking Smart Hydrogel

Temperature-sensitive hydrogel is a hydrogel that undergoes a phase-volume change when the outside temperature changes.Poly(isopropylacrylamide)(PNIPAM)is the most widely used,because its phase volume transition temperature is close to that of the human body,and has a hydrophilic group and a hydrophobic group.However,most of them are poly(isopropylacrylamide)hydrogels crosslinked by organic crosslinking agents.Hydrogels crosslinked by organic crosslinking agents also have some disadvantages,such as:(1)mechanical strength after water absorption is not High,reusable performancis not good;(2)due to chemical cross-linking restrictions on polymer chain movement,even at the medium cross-linking agent concentration,there will be shortcomings such as low swelling degree and slow swelling.In this experiment,poly(isopropylacrylamide)was used as the research object,and poly(isopropylacrylamide)organic-inorganic composite hydrogel was prepared by introducing inorganic components into the organic crosslinking agent.A temperature/pH double response hydrogel formed with carboxymethyl chitosan.The PNIPAM hydrogel was prepared by using clay and N,N-methylenebisacrylamide(BIS)as cross-linking agent.The structure and composition of the hydrogel were characterized.The prepared hydrogel is a continuous porous three-dimensional network structure with a smooth surface.The critical temperature of the hydrogel is consistent with that of the conventional PNIPAM hydrogel,and it is temperature sensitive.When the organic content was 0.0125 g,the clay was added,and the liquid absorption ratio in distilled water was increased from 7 g/g to 22 g/g,and was increased from 5 g/g to 21 g/g in physiological saline.The maximum water retention rate of the hydrogel can reach 32%;in the case of the same concentration of the crosslinking agent,the hydrogel with the inorganic crosslinking agent increases the water retention rate from 4% to 13%.In the simulated intestinal juice,the composite hydrogel can be continuously released for 12 hours under the condition of 37?,and the release rate can reach 82%.The drug release at different temperatures is found to be higher than the critical value.At a temperature of 37?,the release rate is relatively large.A temperature/pH response PNIPAM/CMCS hydrogel was synthesized using clay and BIS with dual sensitivity to temperature and pH.The organic content was 0.0248 g,the liquid absorption ratio in distilled water was increased from 5 g/g to 11 g/g,and the liquid absorption ratio in physiological saline was increased from 5 g/g to 27 g/g.In the case where the concentration of the crosslinking agent is the same,the hydrogel having an inorganic crosslinking agent has a water retention ratio of 5% to 14%.At 37?,the drug can be continuously released for 12 hours in the simulated intestinal fluid environment.When the inorganic content is 0.08 g,the release rate can reach 81%;the organic content is 0.0248 g,and the inorganic content is 0.16 g.Gel,salicylic acid sustained release for 10 h at pH=1.08 and pH=7.4,the total release amount of the drug is not much different,all around 60%.At pH=5.84,the release rate reached 44%;when the drug was released at different temperatures,the release rate was higher at a temperature higher than the critical temperature,such as 37?.