両親媒性ポリマーの調製とその水溶液中におけるカーボンブラックの分散安定性

摘要

Amphiphilic nonionic polymers composed of polyethylene glycol urethanethyl methacrylate (PEGUMA) and ionic copolymers composed of PEGUMA and N,N-dimethylaminoethyl methacrylate (DMAEMA) or methacrylic acid (MAA) were prepared by atom transfer radical polymerization (ATRP) with initiators containing a phenyl group. The resulting polymers, Ph-P(PEGUMA), OS-b-P(PEGUMA), Ph-P(PEGUMA-r-DMAEMA), OS-P(PEGUMA-r-DMAEMA), Ph-P(PEGUMA-r-MAA), and OS-P(PEGUMA-r-MAA) were used as dispersants 1, 2, 3, 4, 5, and 6, respectively. Dispersion stability of carbon black (CB) in aqueous solutions of the dispersant was investigated by UV-vis spectrophotometry at a fixed wavelength (500 nm) and by dynamic light scattering. The dispersion liquids derived from the same type of dispersant (1,2, 3,4, and 5,6) showed different dispersion stability that depends on the number of phenyl groups as the adsorption moiety. The dispersion liquids derived from 3,4 kept a 0% transmittance for three months at 60℃ in the presence of diethylene glycol mono butyl ether. The particle size of the dispersion liquids derived from 3,4 were constant at about 400 nm for three months. Dispersion liquids derived from 3,4 or 5,6 showed a pH-dependant dispersion stability.%原子移動ラジカル重合によって，フユニル基，オリゴスチレン鎖から成る2タイプの吸着部，メタクリル酸ポリエチレングリコールウレタンエチルを用いたノニオン系ポリマー，メタクリル酸2－（ジメチルアミノ）エチルを一部含むカチオン系コポリマー，メタクリル酸を一部含むアニオン系コポリマーといった3タイプのポリマー鎖を親媒部とする計6種類の両親媒性ポリマーを合成した．これらを分散剤とし，ジエチレングリコールモノプチルエーテル存在下，60℃でポリマー水溶液中におけるカーボンブラック（CB）の分散安定性を評価した．同じ系の分散剤を用いて調製したCB分散体は，吸着部のフェニル基数が多いとCB表面により強く吸着し，分散安定性が向上した．中でも，カチオン系分散剤を用いて調製したCB分散体は3ケ月間透過率0％を示し，また粒子径分布の経日変化の結果からも最も良好な分散安定性を示した．