| 초록 |
Much information on amphiphilic block copolymers can be gained using fluorescence probing methods. Pyrene is a widely used fluorescence probe, because its vibrational fine structure is sensitive to polarity and it produces a distinct eximer fluorescence under conditions of sufficiently high concentration and mobility. In this study, the micellar characteristics of poly(vinyl alcohol-b-styrene) (poly(VA-b-St)) diblock copolymers were investigated by means of fluorescence methods using pyrene as fluorescence probing. From the fluorescence emission spectra measurements, the block copolymers formed micelles with critical micelle concentrations (CMC) in the range of 0.125 ~ 4.47 mg/L. The CMC values increase with decreasing the chain length of PS block and with increasing the syndiotacticity of PVA block. The kinetic stability of micelles formed was examined by the time dependence of Ie/Im (pyrene excimer intensity/pyrene monomer intensity) ratio after mixing a micelles containing pyrene with a micelles without pyrene. When the block copolymers contain higher syndiotacticity of PVA block, the rate of release and exchange of large hydrophobic molecules becomes very slow at long time, which indicate that the kinetic stability of the micelles are obviously enhanced. The poly(VA-b-St) copolymer micelles with higher syndiotacticity have a considerably low CMC and higher kinetic stability, which have potential application as drug delivery carriers. |
