Microgels composed of polymeric β-cyclodextrin and polysorbates

초록

Microgels were prepared by taking advantage of an interaction between polysorbates (PSs) and polymeric beta cyclodextrin(P beta CD). PSs (PS 20, PS 40, PS 60, and PS 80) were added to aqueous solutions of P beta CD so that the molar ratio of PS to beta CD residue was about 2:1. On FT-IR spectra, the signals of ester bonds of PSs contained in the microgels were weaker than those of ester bonds in free PSs, and the peak at 1109 cm(-1), corresponding to the -C-O-C functionality of PEO segments of PSs, also decreased in intensity, indicating that both could interact with P beta CD, possibly with the beta CD cavities. The mean diameters of microgels composed of P beta CD/PS 20, P beta CD/PS 40, P beta CD/PS 60, and P beta CD/PS 80 were approximately 0.1, 3.4, 7.3 and 0.05 mu m, respectively. The result that the microgels of P beta CD/PS 40 and P beta CD/PS 60 were much larger is possibly because the tails of PS 40 and PS 60 are longer so that more beta CD can be cross-linked, but for PS 80 the tail is gauche and, therefore, does not fit well into beta CD cavities. The size data were in agreement with the microgels observed on microphotographs. The air/water interfacial activities of PS 40 solutions including P beta CD were markedly less than those of the surfactant solutions without P beta CD, indicating that it was bound to P beta CD.

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