| Gels can be defined as the substance which has a continuous structure with macroscopic dimension that are permanent on the time scale of an analytical experiment and the rheological behavior should be solid-like. This kind of materials has been the focus of intense interest of many scientists due to their applications in many high technology fields such as materials, environment, biology etc. Based upon the fundamental properties of polymeric soft solids, a series of new films, microgels and microgel composites have been prepared and their properties and applications have been studied. The main contents of this dissertation are as follows.(1) Chitosan (CS)/CdS nano-composite films have been prepared via in situ generation of CdS nano-particles. The factors affecting the hydro- thermal stability and the fluorescence properties of the films have been studied. Further more, the sensing properties of the nano-composite films to pyridine in water have been systematically investigated. SEM observation showed that the sizes of the CdS particles are around 70 nm, and the particles are evenly doped within the CS films. The positions of the fluorescence emission of the nano-composite films indicate that the sizes of the real fluorescing CdS particles are less than 20 nm, suggesting that the CdS particles observed via SEM may be aggregates of small CdS particles, and the small particles may be separated by the organics. It has been found that the fluorescence emission of the nano-composite films is very sensitive to the presence of pyridine, and micro-amount of pyridine makes the emission increase dramatically. The emission is hardly affected by common ions in water, except copper and iodide ions. It is predicted that the films may be developed into an excellent sensing films for pyridine in water.(2) The chitosan microgel was prepared with an inverse emul- sion cross-link methods. During the preparation, Paraffin oil was used as a continuous phase. The structural and morphological studies of the micro-spheres were carried out with SEM and FTIR techniques. Combination of the ultrasonic treatment and SEMobservation reveals the hollow structure nature of the microgels. Based upon the special structure of the chitosan microgels, the adsorption of BSA (Bovine serum albumin) on the microgels and the controlled release of the protein were studied in detail. It was found that ①the percent of protein adsorbed does not depend linearly upon the initial concentration of the protein, but the adsorbed amount does increase along with increasing the initial concentration of the protein; ② the amount of protein adsorbed on the microgels has little effect upon the releasing characteristics; ③ the amount of protein adsorbed is pH dependent (pH 5 might be the best at which maximum adsorption amount may be reached).(3) Polysaccharide biopolymer isolated from marine organisms are a new class of potentially inexpensive and environmentally benign solid adsorbents that exhibit a high specifity toward metal ions. Based on the structural and morphological of the cross-linked hollow chitosan microsphere ,the adsorption cadium(II) ions onto chitosan has been investigated, the structure of the adsorption product were carried out with SEM -, FTIR , RS techniques, the adsorption experiment were done at 15-55℃ and over the concentration range 1-2500mg/l,the maximum adsorption capacities for the 60 meshes cross-linked microgels were 420 mg of Cd2+/g of bead at pH=7.0 about 20癈, the molecule weigh, different meshes has little effect upon the adsorption capacities.The studies showed that the CS microsphere has the potential to be used as a novel adsorbents.(4) Poly(memacrylic acid)/PbS(PMAA/PbS) spherical organic - inorganic composites with fishnet-like surface and core-shell structures were prepared by a novel micro-gel template method. The composites were prepared via two steps. Pb(Ac)2 had been dissolved in a MAA solution before it was polymerized into micro-gels in an inverse emulsion syst...
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