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Alumina particle surface interaction in copolymer of isobutylene and maleic anhydride aqueous solution characterized by colloidal probe atomic force microscopy
- Yamamoto, Masahiro, Shimai, Shunzo, Oguma, Kazuki, Wang, Shiwei, Kamiya, Hidehiro
- Powder technology 2019 v.354 pp. 369-376
- aluminum oxide, aqueous solutions, atomic force microscopy, composite polymers, dispersants, gelation, maleic anhydrides, powders, silica
- By the addition of isobutylene-maleic anhydride copolymer, Al₂O₃ aqueous suspensions retain fluidity for approximately 1 h and then gelation occurs. The bi-functionality mechanism as dispersant and gelling-agent of the copolymer was investigated by colloidal probe atomic force microscopy. The time-dependent surface interaction between Al₂O₃ particles and sapphire substrates were compared to those of SiO₂, the suspension of which did not appear experience gelation. After 40 min, repulsive forces increased slightly and attractive forces decreased dramatically with short-range character, corresponding to the dispersant action of the copolymer in aqueous Al₂O₃. As aging time increased to 2 h, a large repulsive force and long-range attractive force developed. With the aging time going to 3 h, the repulsive force disappeared and only long-range attractive forces remained. On the contrary, in the case of SiO₂, long-range repulsive force was only observed after the addition of ISOBAM, and long-range attractive interactions were not observed with increased of aging time. However, no time-dependent long-range attractive interaction was observed in the SiO₂ suspension. Therefore, it seems gelation of the Al₂O₃ aqueous suspension was correlated to the long-range attractive interaction between Al₂O₃ surfaces.