| 초록 |
Symmetric ABA triblock copolymer is known to exhibit the very similar morphology as the AB diblock copolymer having a half of the ABA triblock copolymer. The comparative studies of two block copolymers have been reported, but their molecular structures were not exactly in the 2:1 ratio. In this study, we used the triblock and diblock copolymers of precisely 2:1 molecular structure. The polystyrene-block-polyisoprene-block-polystyrene (PS-b-PI-b-PS) copolymer was synthesized from the PS-b-PI copolymer precursor anions by coupling them. The added amount of the coupling agent was less than the stoichiometric ratio to yield a mixture of the triblock and diblock copolymers. The mixture was fractionated by HPLC. Therefore, the triblock copolymer has precisely the same composition and twice the molecular weight as the diblock copolymer. The fractionated block copolymers were characterized by NMR and GPC, and their phase behaviors and morphologies were measured by SAXS and TEM. |
