Study On Synthesis And Properties Of Environmentally Responsive Semi - Interpenetrating Polymer Network Hydrogels

Hydrogel can take a change in size or shape due to the physical or chemical conditions of the environment. In this paper, we used solution polymerization, and have different functional groups of monomers in the alginate solution, cross-linked and polymerized to get the environment responsive Semi-IPN polymer network hydrogel, which better meet the requirements of different environments to respond faster to achieve the goal of intelligent materials.1. Preparation of alginate/PAA Semi-IPN hydrogel and its response behavior with electrical stimulationSA/PAA Semi-IPN hydrogel with different content of crosslinking agent was prepared by solution polymerization, their water absorption, rheo logical properties and electrical response to stimulation was studied, and infrared spectroscopy (IR) and SEM was used to study its microstructure. The results showed that:the monomer almost entirely reacted. The research of water absorption showed that the maximum swelling ratio is up to72.80g/g. With increasing crosslinker and concerntration, the swelling ratio get reduced; the study of rheological properties showed that due to the formation of the crosslinked network, SA/PAA hydrogel showed high viscosity and elasticity, and experienced the transition from liquid to gel state; The study of response of hydrogel to electrical stimulation showed that the gel bend towards cathode and the bending angle increased with the increasing electric field which up to90degree; The bending angle of the gel strip increased with increasing pH and be reversible in the direct electric field when pH<6.2. Prepartion of SA/PNIPAM Semi-IPN hydrogel with temperature and pH sensitivity and its response properties.SA/PNIPAm Semi-IPN hydrogel was prepared by solution polymerization and its sensitivity to temperature and pH was studied. The conclusion was that the Semi-IPN hydrogel was transparent and uniform, smooth and elastic at room temperature, and almost no remnants of small molecule impurities, but when the temperature rose to above LCST, the hydro gel became turbid opaque. It showed that there were large holes inside the equilibrium swelling hydrogel network. But when the hydrogel got dried to constant weight, the internal pore of the gel got contract to disappear.3. Preparation and properties of nano-composite Semi-IPN hydro gels containing Paramagnetic Fe3O4.Paramagnetic Fe3O4nanoparticles were prepared by co-precipitation method inside the Semi-IPN hydrogeL It also provides a very effective way to prepare monodisperse nanoparticles using macroporous hydrogel as templates. It showed that the proportion of Paramagnetic Fe3O4was almost the same detected by FESEM, VSM and TG. The nanocomposite prepared from the same hydrogel is also temperature sensitive, the LCST of the hydrogel isn’t affected even though the formation of iron oxide by DSC.4.Gel image analysis method to monitor its deformation characteristics.This paper presented a measurement method based on image analysis, which could monitor the whole process of the deformation properties of hydrogels. In this method, the CCD camera was first used to collect the series of images when the hydrogel was in some condition, then each image of the hydrogel and ruler would get precise position, then calculate the measurement data of deformation of the gel, and finally obtain the fitting curve of the deformation hydrogel. The results showed that the gel volume tend to decrease with increasing temperature in the closed container.The significance of this research was that the intelligent gel which was sensitive to external environment, such as temperature, pH, ionic strength, and the electric field, magnetic field was obtained by choosing special group of compounds crosslinked and polymerized in the biocompatible macromolecules. It had wide application in drug control and release, chemical memory cell switches, artificial muscles, sensors and so on. According to the characteristics of the experimental hydrogel image, a measurement method based on image analysis was also presented in this subject. This method had a character of high sensitivity, high detection speed, without any object contact surface of the part, no coupling agent, no special requirements to the shape of the measured object and the state of the suface, can show the state of deformation directly, and the test results were easy to save, which had broad application prospects.