Akademik Veri Yönetim Sistemi
MACROMOLECULES, cilt.39, sa.3, ss.1216-1225, 2006 (SCI-Expanded)
A series of novel "schizophrenic" ABC triblock copolymers, 2-(diethylamino)ethyl methacrylate-b-2-(dimethylamino)ethyl methacrylate-b-2-(N-morpholino)ethyl methacrylate [PDEA-PDMA-PMEMA], has been synthesized by using group transfer polymerization. These triblock copolymers dissolved molecularly in aqueous solution at low pH (< 6.6) due to protonation of all tertiary amine residues of the three blocks and formed three-layer "onionlike" micelles at pH 7.6 by PDEA block forming the micelle cores, PDMA block forming the inner shells, and PMEMA forming the coronas. On the other hand, by the addition of Na2SO4 to the molecularly soluble polymer solution at pH 6.5 the neutral PMEMA-block became hydrophobic due to the salting-out effect and another three-layer "onionlike" micellization occurred, comprising PMEMA cores, PDMA inner shells, and PDEA coronas. DLS studies indicated nearly-monodisperse micelles in both cases. The intensity-average radii of the PMEMA-core and the PDEA-core micelles were 10.1 nm (polydispersity index, mu(2)/Gamma(2) = 0.10) and 12.9 nm (mu(2)/Gamma(2) = 0.08), respectively. It was also observed that these triblock copolymers formed PMEMA-core micellization in n-hexane. Finally, two types of novel shell cross-linked micelles (PDEA-core in aqueous media and PMEMA-core in n-hexane) were also prepared from these remarkable PDEA-PDMA-PMEMA triblock copolymers by cross-linking the inner PDMA shell of the micelles. In shell cross-linking of both micelles, the outer PDEA or PMEMA shell acted as steric stabilizer and prevented intermicelle aggregation even when the cross-linking chemistry was carried out at high polymer concentrations.