COLL 219 |
| Futian Liu and Adi Eisenberg. Department of Chemistry, McGill University, 801 Sherbrooke Street West, Room 446, Montreal, QC H3A 2K6, Canada |
| Amphiphilic block copolymers, such as polystyrene-block-poly(acrylic acid) (PS-b-PAA) and polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) can self-assemble to form various aggregates, including vesicles, in aqueous solutions. We now investigate the triblock poly(acrylic acid)-block-polystyrene-block-poly(4-vinyl pyridine) (PAA-b-PS-b-P4VP) with a basic and an acidic end block separated by a neutral hydrophobic segment as a new candidate for the formation of vesicles. We examine the effects of pH and relative corona block lengths on the preferential segregation of the acidic or basic corona chains to the inside or the outside in the vesicles. x potential measurements are used to characterize the outside surfaces of the aggregates. The results show that both the pH under preparative conditions as well as the relative corona block lengths exert a strong effect on the preferential segregation of the corona blocks. If the different corona blocks have similar block lengths, as in. PAA26-b-PS890-b-P4VP40, asymmetric vesicles with a polystyrene wall and with either PAA on the outside and P4VP on the inside, or vice versa, can be prepared from the same triblock under different pH conditions; moreover, triggered inversion of the vesicles from PAA outside/P4VP inside to the opposite configuration is successful; however, if the corona blocks have significantly different block lengths, as in PAA44-b-PS906-b-P4VP132, only asymmetric vesicles can be prepared with the longer corona chains segregated to the outside of the vesicles. |
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Posters: Fundamental Research in Surface and Colloid Chemistry
6:00 PM-8:00 PM, Monday, March 29, 2004 Disneyland -- North Exhibit Hall, Poster
Division of Colloid and Surface Chemistry |