| 초록 |
We investigated the difference of phase diagram of 18-arm star-shaped polystyrene-block-poly(methyl methacrylate) copolymers ((PS-b-PMMA)18) depending on the degree of initiation of the second PMMA. Star-shaped block copolymers, using different catalysts CuBr and CuCl, were synthesized by using α-cyclodextrin (α-CD) as a core of the star-shape. When CuBr was used for catalyst, PMMA was linked to only 75% of PS arm and, in the case of CuCl for calatlyst, PMMA was linked to 100% of PS arms perfectly. The reason is that, using CuCl for catalyst, reaction rate of propagation of PMMA to PS whose end is bromine is similar to that of PMMA to PMMA whose end is chloride. Because of this difference, phase diagram depending on shell part volume fraction was different. Those block copolymers were characterized by gel permeation chromatography and nuclear magnetic resonance. Morphology of Star-shaped block copolymer was characterized by TEM and small angle X-ray scattering. |
