Study On Preparation And Properties Of Hydroxypropyl Cellulose-Based Hydrogel

Stimuli-sensitive hydrogels are able to absorb and release water solutions in a reversible manner, in response to specific environmental stimuli, including pH, temperature, ionic strength, and so on. Such stimuli-sensitive behavior makes hydrogels appealing for the design of’smart’ devices, applicable in a variety of technological fields. particularly in cases where either ecological or biocompatible issues are concerned. Cellulose and their derivatives have been widely used to prepare stimuli-sensitive hydrogels due to the low cost, the large availability, the biocompatibility and biodegradability of cellulose, and the responsiveness of some cellulosics to variations of external stimuli. Here, hydroxypropyl cellulose (HPC) based composite hydrogels were prepared which show potential application in drug delivery and dye adsorbents. The main contents of the research are as follows:1.The polymerizable macromonomer of hydroxypropyl cellulose acrylate (HPCA) was prepared by the esterification reaction of hydroxypropyl cellulose and acryloyl chloride (AC). The magnetic and pH-responsive hydrogels of poly(hydroxypropyl cellulose acrylate-co-acrylic acid) composited with FeaO4 (P(HPCA-co-AA) @ Fe3O4) were prepared by precipitation polymerization and in situ coprecipitation. The structure of the products was confirmed using FT-IR and 1H NMR. Effects of different mole ratios of hydroxy (-OH)/AC and reaction time on the degree of acetyl grafted on hydroxypropyl cellulose were investigated. The release behavior of the hydrogels at different pH was studied, using sodium salicylate as a model drug. The results revealed that the best way for preparing HPCA was that mole ratio of-OH)/AC and reaction time was 1/1.2 and 24 h; the hydrogels of P(HPCA-co-AA)@ Fe3O4 was demonstrated to have good magnetic targeting in an external magnetic field; and the higher pH value triggered more accumulative drug release, resulting from the swelling of the hydrogels.2.The graphene oxide (GO) sheets were first grafted with HPC chains, then the microporous temperature-responsive GO-HPC/HPC hydrogels were prepared by the modified temperature-induced phase separation (TIPS). Finally, taking methylene blue (MB) as a model dye, the adsorption property of the hydrogels was investigated. The hydrogels exhibited temperature sensitivity and higher swelling ratios were observed at a lower temperature in the solution. The swelling ratios of composite hydrogels first decreased and then increased with the increase of GO-HPC. The composite hydrogels had higher adsorption capacity for MB than pure HPC hydrogels, and the composite hydrogels absorbed more MB with the increase of GO-HPC. The pseudo-second-order kinetic model well described the adsorption behavior of the MB on both GO-HPC/HPC hydrogels and HPC hydrogels. The Freundlich isotherm was a more applicable model to the equilibrium adsorption of GO-HPC/HPC hydrogels while the Langmuir isotherm model was a more applicable model for the equilibrium adsorption of HPC hydrogels.3.The exfoliated molybdenum disulfide (MoS2) sheets were grafted with HPC chains and the microporous temperature-responsive MoS2-HPC/HPC hydrogels were prepared. The adsorption property of MB on the hydrogels with different weight ratios of MoS2-HPC was investigated. The MoS2-HPC/HPC hydrogels were found to have temperature sensitivity and higher swelling ratios were observed at a lower temperature in the solution. The swelling ratios of composite hydrogels decreased with the increase of MoS2-HPC. The results indicated that the composite hydrogels had higher adsorption capacity for MB than pure HPC hydrogels, and the composite hydrogels absorbed more MB with the increase of MoS2-HPC. Furthermore, the pseudo-second-order kinetic model could well described the adsorption behavior of the MB on both HPC hydrogels and MoS2-HPC/HPC hydrogels and the Langmuir isotherm model could well describe the equilibrium adsorption of both HPC hydrogels and MoS2-HPC/HPC hydrogels. Besides, MoS2-HPC/HPC hydrogels were used to catalyze the degradation of MB upon exposure to sun light, then the hydrogels were circularly used to absorb MB.