Akira Ueda

Synthesis of (AB)n-type block copolymers employing surface-active macro-azo initiators

A macro-azo initiator (MAI), prepared by polycondensation of azobiscyanopentanoyl chloride (ACPC) and polyethyleneglycol having average molecular weight of 1000 (PEG1000), was found to show enough surface activity to be usable as an initiator/surfactant (inisurf). Emulsion polymerization of styrene (St) using this MAI as inisurf was carried out and (AB) n -type poly(PEO-b-PSt) block copolymer (where n represents the block-multiplicity) was obtained. In comparison with solution copolymerization, the emulsion hlock copolymerization gave PEO-b-PSt with higher molecular weight due to increased hlock multiplicity.

Synthesis of new macro‐azo‐initiators having two kinds of azo linkages in repeating unit and block copolymerization by two‐step radical polymerization initiated with them

Two kinds of new macro-azo-initiator (MAI) having dual decomposition temperatures were synthesized by polycondensation between 4,4-azobis-4-cyanopentanoyl chloride (ACPC) and 2,2-azobis-2-cyanopentanol (ACPO) (MAI [2A]), and between ACPC and 2,2-azobis-2-methyl-N-2-hydroxyethylpropionamide (AHPA) (MAI [2B]). MAI [2A] and [2B] were compared with MAI [1] having a single decomposition temperature synthesized by polycondensation between ACPC and bisphenol-Z. Two step polymerization of styrene and methyl methacrylate initiated with MAI [1], [2A], and [2B] was carried out. It was confirmed that the new MAI [2A] and [2B] initiated effectively at each step of polymerization due to their dual decomposability, resulting in higher conversion of the comonomers to yield block copolymers than the case initiated with MAI [1].