Convenient synthesis of microspheres by self-assembly of random copolymers in supercritical carbon dioxide |
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Authors: | Eri Yoshida Akito Nagakubo |
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Institution: | (1) Department of Materials Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi Aichi, 441-8580, Japan |
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Abstract: | A novel and convenient synthesis of microspheres was attained by molecular self-assembly of random copolymers in supercritical
carbon dioxide. Poly{2-(perfluorooctyl)ethyl acrylate-ran-2-(dimethylamino)ethyl acrylate} random copolymers (PPOA-r-DAA]), with 7:3, 8:2, and 9:1 as the molar ratios of 2-(perfluorooctyl)ethyl acrylate (POA)/2-(dimethylamino)ethyl acrylate
(DAA), were soluble in supercritical CO2 and had their cloud points at about 75 bar higher than the critical pressure of CO2. The CO2 density at the cloud points decreased with an increase in temperature. Although the copolymers made a slight difference in
the cloud point in the absence of perfluoroazelaic acid (PA), they made a marked difference in the presence of PA. The copolymer
with a lower DAA content had a cloud point at lower CO2 density. The scanning electron microscopy observation demonstrated that the copolymers produced microspheres in the presence
of PA at 0.5 as PA/DAA in the heterogeneous state below the cloud points. The microspheres were unstable to pressure and changed
to unspecific forms as a result of increasing the CO2 pressure, although the microspheres were stable to temperature. The POA/DAA ratio in the copolymer had effect not only on
the cloud point but also on the size of the microspheres. The copolymer with a lower DAA content formed smaller microspheres. |
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Keywords: | Poly{2-(perfluorooctyl)ethyl acrylate-ran-2-(dimethylamino)ethyl acrylate} Perfluoroazelaic acid Supercritical carbon dioxide Cloud point Microspheres |
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