Poly(vinyl alcohol) hollow microcapsules prepared by emulsification, salting out, and photo cross-linking method

초록

Coumarin residues were conjugated to poly(vinyl alcohol) (PVA) by reacting epoxypropoxy coumarin (EPC) with the polymer. According to the peak areas on the H-1 NMR spectrum, EPC was calculated to be conjugated to every 283 repeating units (vinyl alcohols). A cyclic photo-dimerization and dedimerization of EPC of PVA-EPC conjugate were observed under a cyclic irradiation of 365 nm and 254 nm. The salting-out of the conjugate significantly took a place in the range of 0-2.0 M NaCl, and the phenomenon was observed at a lower concentration than that of unmodified PVA was. Oil-in-water emulsion was prepared as a template for the preparation of hollow microcapsules using chloroform as an oil phase and PVA-EPC as an emulsifier. The emulsion was stable for 24 hr in terms of droplet size. The wall surrounding droplets was built-up by the salting-out of PVA-EPC, and it was cross-linked by the irradiation of 365 nm. After chloroform was evaporated and salt was removed by a dialysis, hollow microcapsules were successfully obtained.

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