| Summary: | 碩士 === 國立臺灣科技大學 === 高分子系 === 95 === In this study, dextran hydrogels grafted with various volume content of PEG were prepared by polymerization of aqueous solution of glycidyl methacrylate derivatized dextran(dex-MA). The objective is to demonstrate the influence of grafting parameters on the mesh size in PEG-grafted dextran hydrogels.
With increasing contents of PEG, PEG grafted chains make water contents of hydrogels increased. In the compressive stress experiment, the modulus and the effective crosslinking density (ve) increased with the increasing contents of grafted chains. As the crosslinking densities increase, the molecular weights between the crosslinks (Mc) of gels decrease. The hydrogel mesh size (ξ) increasing of water contents increased.
The releases of BSA and Vitamin B12 from hydrogels varying in degrees of substitutions and water contents, are investigated to understand the “free volume of diffusion” and “length of diffusion path” in terms of the molecular parameters of diffusants and gels.
In addition, as the water contents increase, the tortuosity of solutes diffusion in the gels decrease. As the ratio of diameter of solutes to mesh sizes of the gels lie between 0.1 to 0.8, a significant deviation of 200% between the experimental and predicted values is found. However, there’s a large deviation between the experimental and the predicted values at higher ratio. The theoretical lines can’t overlap with experimental data, therefore, it’s believed that the shape in solutes can also affect the tortuosity of solutes diffusion in gels.
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