期刊
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
卷 41, 期 21, 页码 3425-3439出版社
WILEY
DOI: 10.1002/pola.10940
关键词
atom transfer radical polymerization (ATRP); macromonomers; graft copolymers; kinetics (polym.); n-butyl acrylate
Poly(n-butyl acrylate) macromonomers with predetermined molecular weights (1300 < number-average molecular weight < 23,000) and low polydispersity indices (<1.2) were synthesized from bromine-terminated atom transfer radical polymerization polymers via end-group substitution with acrylic acid and methacrylic acid. These macromonomers, having a high degree of end-group functionalization (>90%), were radically homopolymerized to obtain comb polymers. A high macromonomer concentration, combined with a low radical flux, was needed to obtain a high conversion of the macromonomers and a reasonable degree of polymerization. By the traditional radical copolymerization of the hydrophobic macromonomers with the hydrophilic monomer N,N-dimethylaminoethyl methacrylate (DMAEMA), amphiphilic comb copolymers were obtained. The conversions of the macromonomers and comonomer were almost quantitative under optimized reaction conditions. The molecular weights were high (number-average molecular weight approximate to 70,000), and the molecular weight distribution was broad (polydispersity index approximate to 3.5). Kinetic measurements showed simultaneous decreases in the macromonomer and DMAEMA concentrations, indicating a relatively homogeneous composition of the comb copolymers over the whole molecular weight range. This was supported by preparative size exclusion chromatography. The copolymerization of poly(n-butyl acrylate) macromonomers with other hydrophilic monomers such as acrylic acid or N,N-dimethylacrylamide gave comb copolymers with multimodal molecular weight distributions in size exclusion chromatography and extremely high apparent molecular weights. Dynamic light scattering showed a heterogeneous composition consisting of small (6-9 nm) and large (23-143 nm) particles, probably micelles or other type of aggregates. (C) 2003 Wiley Periodicals, Inc.
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