Preparation And Poperties Improvment Of PNIPAM Temperature Sensitive Hydrogel

Hydrogel is a kind of material which can absorb large amount of water while keep its structure.With the properties of absorption and good biocompatibility,Hydrogel is supposed to be applied in field of separation,tissue engineering,biomedical materials.According to whether the hydrogel can response to the environment or not,it can be classified to normal and intelligent hydrogel.Intelligent hydrogel,which keep the properties of normal hydrogel as well,can respond to the external environmental factors such as temperature,light,electric field,magnetic field,pH and so on,so it is of singnifcant to study the intelligent hydrogel.The temperature sensitive hydrogel is a kind of intelligent hydrogel which could undergo volume phase change at the critical temperature,the poly N-isopropylacrylamide(PNPAM)hydrogel of which the critical tempreture(32oC)is close to the body temperature could squeeze the water out when it is deswelling at temperature above 32 oC,so it has tremendous potential applications in drug controlled release carrier materials.However,in the practical application as drug controlled release materials,PNIPAM hydrogels still have the defects of poor mechanical strength and releasing low amount of drugs at critical temperature.It is of singnificant for understand PNIPAM hydrogels deeper and appling it to drug control releasing system to develop the corresponding properties of PNIPAM hydrogels.In the paper,A facile one-pot method was developed to synthesis thermosensitive PNIPAM/Ca-alginate interpenetrating network hydrogels.With the method,the crosslink of alginate by Ca2+ and polymerization and crosslink of NIPAM occurred in a single reactor at the same time.Using CaSO4·2H2O slow down the gel rate of alginate and make the crosslinker CaSO4·2H2O disperse uniformly futher lead to homogeneous hydrogel.The molecular structure of PNIPAM/Ca-alginate interpenetrating network hydrogels were determined by infrared spectroscopy experiments,the internal morphology of hydrogels was observed by scanning electron microscope,mechanical strength and swelling properties were investigated.The results indicated that:(1)Compared with the preparation process of traditional IPN hydrogels,the one-pot method is simple and quick,reducing the period of preparing IPN hydrogel which is two times longer before;(2)Compared with the traditional temperature sensitive hydrogel,PNIPAM/Ca-alginate interpenetrating network hydrogels have excellent mechanical properties,the hydrogel which is added to 10% SA of CaSO4·2H2O have a compressive strength of 35 KPa while the compressive strength of traditional hydrogel is 10 KPa,and the mechanical strength increases with the amount of CaSO4·2H2O added;(3)PNIPAM/Ca-alginate interpenetrating network hydrogels have good thermalsensitive properties;(4)The swelling ratio of PNIPAM/Ca-alginate interpenetrating network hydrogels reduce along with increasing of the amount of CaSO4·2H2O.In the paper,CaCO3 as pore forming agent and sodium carboxymethyl cellulose as Auxiliary agent were used to prepare porous temperature-sensitive hydrogel.The carboxymethyl cellulose was added to adjust the viscosity of reaction solution to make CaCO3 disperse uniformly,the uniform dispersion of CaCO3 can make the pore structure uniformly distribute.The molecular structure of the hydrogels is determined by infrared spectroscopy,the pore structure of the hydrogels was observed by scanning electron microscope,the swelling behavior of hydrogels was investigated.With bovine serum albumin being as model drug,the performance of drug control release of the hydrogels prepared were investigated.The results show that:(1)The pore structure of the hydrogels prepared is uniformly distributed and penetrated;(2)Compared with that of non-porous hydrogel,the swelling and deswelling rate of porous hydrogels increased singnificantly;(3)Compared with that of non-porous hydrogels,the bovine serum albumin cumulative release mount of porous hydrogels was significantly increased when above critical temperature,the bovine serum albumin cumulative release of hydrogel which is added 0.03 g is 45% while that of traditional hydrogel is 35%..