Research On The Synthesis And Characterization Of UV Curing Polyurethane Hydrogel

Hydrogel is a kind of soft material usually composed of 3 dimensional,insoluble,cross-linked polymer networks that can uptake a huge amount of water inside its network.Characteristic properties such as high water absorption capacity,desired functionality and biocompatibility make hydrogels an ideal substance for a variety of applications.The traditional method of hydrogels preparation is to synthesis cross-linked polymer first then swelling in the water,these hydrogels often have poor mechanical property,while polyurethane(PU)materials have good mechanical properties and devisable versatilities.In this work,the excellent properties derived from polyurethane and hydrogel were banded together.A series of UV-curable polyurethane hydrogel precursors were synthesized by pre-polymerizing polyethylene glycol(PEG),isophorone diisocyanate(IPDI),2-hydroxyethyl acrylate(HEA),1,4-butanediol(BDO)and glycerol(GLY),then polyurethane hydrogel was prepared by UV curing crosslinking.The prepared PU hydrogels were characterized by structural(FITR,1H-NMR,GPC),mechanical,thermal and swelling testing(including the maximal swelling rate,swelling kinetics,effects of temperature,pH and ionic strength on swelling properties).The structures of PU hydrogel were analyzed by FTIR,1H-NMR and GPC tests.The results indicated that its structures were in accordance with the experimental design.The mechanical test showed that molecular weight of PEG and the rate of BDO/(BDO+GLY)both have influence on mechanical properties of PU hydrogel film.With the increase of the molecular weight of PEG,the tensile strength of hydrogel film decreases and then increases.When the molecular weight of PEG is more than 2000 and less than 6000,the tensile strength increases with the increase of molecular weight of PEG.The thermal analysis showed that the prepared PU hydrogel has good advantages of water absorption,water holding capacities and better thermal stability.The swelling tests indicated that molecular weight of PEG,rate of BDO/(BDO+GLY),temperature and ionic strength all have influence on the PU hydrogel swelling properties,while pH has a little influence on it.With the increase of the molecular weight of PEG or the rate of BDO/(BDO+GLY),the swelling ratio of PU hydrogel increased,but swelling ratio decreases with the increase of temperature.When the ionic strength increases,the swelling ratio will decrease in a small degree.The swelling kinetics study showed that the prepared PU hydrogel swelling process accords with the Fick diffusion model,which is controlled by the water diffusion.Moreover,the application of prepared PU hydrogel was discussed.On the one hand,the application of the prepared hydrogel used as wound dressing was studied.On the other hand,the potential application of the prepared hydrogel used as thermotropic materials was researched.Taking PUH3 hydrogel as an example,the drug loading and releasing properties were studied using the GS as the drug.The results indicated that the prepared PU hydrogel has abilities to load and release the drug under suitable conditions.Besides,the release kinetics study showed that the reledase process accords with the double exponential equation,which can be used to predict drug release.The thermotropic composite was prepared by integrating NP-9 salt solution with PU hydrogel which used the PEG4000 as the soft blocks.The thermal-sensitive property study indicated that the composite is transparent within a certain range of temperature,when the temperature exceeds this certain range,the composite became turbid and the light transmittance changed a lot,and showing a good light adjusting property.