Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-(N,N- dimethylamino)ethyl methaerylate] (PIB-b-PDMAEMA) and polyisobutylene-block-poly(metharylic acid) (PIB-b-PMAA), were ...Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-(N,N- dimethylamino)ethyl methaerylate] (PIB-b-PDMAEMA) and polyisobutylene-block-poly(metharylic acid) (PIB-b-PMAA), were synthesized via oxyanion-initiated polymerization, and their multiple self-assembly behaviors have been studied. An exo-01efin-terminated highly reactive polyisobutylene (HRPIB) was first changed to hydroxyl-terminated PIB (PIB-OH) via hydroboration-oxidation of C =C double bond in the chain end, and then reacted with KH to yield a potassium alcoholate of PIB (PIB-O-K+). PIB-O-K+ was immediately used as a macroinitiator to polymerize DMAEMA monomer, resulting in a cationic diblock copolymer PIB-b-PDMAEMA. With the similar synthesis procedure, the anionic diblock copolymer PIB-b- PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate (tBMA) and subsequent hydrolysis of tert-butyl ester groups in PtBMA block. The functional PIB and block copolymers have been fully characterized by 1H-NMR, FT-IR spectroscopy, and gel permeation chromatography (GPC). These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent. Transmission electron microscopy (TEM) images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles, vesicles with different particle sizes and cylindrical aggregates, depending on various factors including block copolymer composition, solvent polarity and pH value.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 20974074 and 21074078)Natural Science Foundation of Jiangsu Province for Rolling Support Project (BK2011045)+1 种基金a project funded by the PriorityAcademic Program Development of Jiangsu Higher Education Institutions, State Key Lab of Chemical Resource Engineering(Beijing University of Chemical Technology)the Innovation Project of Graduate Students of Jiangsu Province, China(CXZZ11_0091)
文摘Two pH-responsive amphiphilic diblock copolymers, namely polyisobutylene-block-poly[2-(N,N- dimethylamino)ethyl methaerylate] (PIB-b-PDMAEMA) and polyisobutylene-block-poly(metharylic acid) (PIB-b-PMAA), were synthesized via oxyanion-initiated polymerization, and their multiple self-assembly behaviors have been studied. An exo-01efin-terminated highly reactive polyisobutylene (HRPIB) was first changed to hydroxyl-terminated PIB (PIB-OH) via hydroboration-oxidation of C =C double bond in the chain end, and then reacted with KH to yield a potassium alcoholate of PIB (PIB-O-K+). PIB-O-K+ was immediately used as a macroinitiator to polymerize DMAEMA monomer, resulting in a cationic diblock copolymer PIB-b-PDMAEMA. With the similar synthesis procedure, the anionic diblock copolymer PIB-b- PMAA could be prepared via a combination of oxyanion-initiated polymerization of tert-butyl methacrylate (tBMA) and subsequent hydrolysis of tert-butyl ester groups in PtBMA block. The functional PIB and block copolymers have been fully characterized by 1H-NMR, FT-IR spectroscopy, and gel permeation chromatography (GPC). These samples allowed us to systematically investigate the effects of block composition on the pH responsivity and various self-assembled morphologies of the copolymers in THF/water mixed solvent. Transmission electron microscopy (TEM) images revealed that these diblock copolymers containing small amount of original PIB without exo-olefin-terminated group are able to self-assemble into micelles, vesicles with different particle sizes and cylindrical aggregates, depending on various factors including block copolymer composition, solvent polarity and pH value.