| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
This study reports novel synthetic of hydrophobic-hydrophilic gradient gradient gel by the esterification of outer DBU salt of poly (acrylic acid) gel (DAA) with alkyl halide to give new amphiphilic core-shell typed gel which is poly (acrylic acid) gel covered and bound chemically with hydrophobic shell layr. When the gel was placed in an aprotic polar solvent containing excess alkyl halide, swelling occurred and the gel was divided into a swollen shell and an unswollen core. When R and r are radius of shell and core after t min, respectively, the apparent ratio of reacted gel to the original gel was determined as function of r/R.The rection was followed as a function of r/R and analyzed kinetically using homogenous model. The overall reaction consisted of rates of diffusion of alkyl halide through swollen shell, esterification, and diffusion of alkyl halide through unswollen core. There are three rate-controlling steps ; diffusion through swollen shell control, esterification control, diffusion through unswollen core control. The reaction was affected markedly by readctivity and bulkiness of alkyl halide. Furthermore, the thermal acid-catalyzed deesterification of poly (t-butyl methacrylate) gel from the inner gives similar core-shell typed gel. We prepared gel casules based on this background. When the gel capsules containing chemicals were dipped in solution, the release of chemical took place with swelling the gels. This results suggested that the chemical release from the gel capsule controlled by the thickness of the shell layr and chemical structures. Therefore, the obtained gel capsule is useful for control release.
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