| Poly(N-isopropylacrylamide)(PNIPAM) has both hydrophilic acylamino and hydrophobic isopropyl, and exhibits a lower critical solution temperature (LCST) around32℃. The favorable thermosensitive properties of PNIPAM hydrogel have been of great interest for a wide variety of potential applications, for instance, drug delivery, material separation, enzyme immobilization and recyclable absorbent etc.In order to solve the problems of conventional PNIPAM hydrogel, such as poor biological affinity, slow response rate and low swelling/deswelling rates etc. In this paper, intelligent hydrogels were sythesized by adding acrylic acid (AA), biocompatible carboxymethyl chitosan (CMCS), attapulgite (ATP) and Fe3O4particles etc, and the properties of the modified hydrogels were preliminarily studied.(1)A series of P(NIPAM-co-AA)/ATP intelligent hydrogels with temperature and pH responsive properties were synthesized by the copolymerization of acrylic acid and attapulgite with N-isopropylacrylamide in this work. The shape and conformation of gel were determined by scanning electron microscopy and Fourier trasform infrared spectroscopy. The addition of AA and the ATP can increase the swelling behavior of hydrogels, but with the addition of AA, its LCST increased. When the pH value was8.0, a maximum swelling ratio was observed. The factors influencing adsorption capacity of hydrogels, such as the value of pH, temperature, the initial concentration and adsorbent dose of adsorbent were systematically investigated, then the optimal conditions of adsorption were obtained. The thermodynamics and dynamics for the adsorption were discussed. The results showed that adsorption process could be better described with Langmuir equation, and the Kineties data for the adsorption fitted very well to the Pseudo-second rate equation. In acidic medium, the hydrogel has a favorable desorption property of methyl violet dye. It can be expected to achieve the adsorbent recycling and reuse.(2)We prepared the rapid responsive hydrogels by choosing the copolymerization of CMCS with NIPAM, and using PEG as a pore-forming agent during the polymerization reaction. Then the multiple stimuli sensitive hydrogels were fabricated by in situ embedding of magnetic iron oxide nanoparticles into the porous hydrogel networks. The results show that the phase transition temperature of hydrogels was around34.0℃, which indicates that the addition of Fe3O4and molecular weight of PEG did not change the gel network structure. With the increase of PEG molecular weight, the hydrogel pore size and the equilibrated swelling ratios become larger. The saturation magnetization tends to decrease, but still meet the purpose of magnetic separation. In vitro drug release system, we selected cefazolin sodium as a drug model to investigate the release property of the drug-loaded gels. The results showed that the release property at37℃is better than that at room temperature. It is more convenient for the drug release in the medium when pH=7.4.(3)A composite particle of Fe3O4/ATP-PNIPAM was successfully prepared by the combination of Fe3O4/ATP and PNIPAM. The structure, morphology, magnetic and thermosensitive properties of the composite particles were preliminarily investigated. It was found that the composite particles had also both magnetic and thermo-sensitive dual response characteristics when taking the excellent performance of the attapulgite clay, It also showed that this synthesized multifunctional material had a potential application value in biomedical field. |
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