| 초록 |
It was an object of the present proceeding to produce poly(lactic acid) in the form of microspheres by brand-new process which is capable of alternating the existing process which requires very high temperature and vacuum to allow the removal of the condensate molecule from the polymer melt. The removal of the condensate molecule is facilitated by the ability of supercritical CO2 to act as a plasticizing agent for the polymer phase. In this approach, the preparation of stable dispersions of PLA via dispersion polymerizations in a CO2 contiunous phase has been investigated. Poly(DMS-b-CL) copolymer with CO2-phobic and CO2-philic group was used as the stabilizers of various chemical compositions. Reactions were conducted at pressure of 2700~3500 psi and the temperature of 50~150 oC, Metal and acid-based catalyst was employed as the initiator. Effects of variations in the reaction temperature, pressure, stabilizer composition, stabilizer concentration, on the resulting product were investigated. The spherical polymer particles were isolated by simply venting the supercritical CO2 from the reaction mixture. Scanning electron microscopy showed that the product consisted of spheres in the micrometer size range.
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