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Preparation of nano‐ and microparticles through self‐assembly of azobenzene‐pendent ionomers
Author(s) -
Mori Takeshi,
Yuyama Keijiro,
Narita Kanae,
Minagawa Keiji,
Haraguchi Masanobu,
Tanaka Masami
Publication year - 2006
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.22762
Subject(s) - azobenzene , copolymer , aqueous solution , polymer chemistry , materials science , particle size , methacrylate , particle (ecology) , colloid , chemical engineering , solvent , volume fraction , chemistry , organic chemistry , polymer , composite material , oceanography , engineering , geology
The particle formation of azobenzene‐containing ionomers, through self‐assembly, in aqueous media (THF/H 2 O solvent) was studied. The ionomers were synthesized by copolymerization between azobenzene‐pendent methacrylate and methacrylic acid. It was revealed by UV–vis spectra and light scattering measurements that the extent of H‐aggregation of the azobenzene units first decreased, and then increased with increasing volume fraction of H 2 O of the solvent. The H 2 O fraction at which the extent of H‐aggregation began to increase became lower, when the copolymers contained more azobenzene units. Colloidal particles were prepared by slow addition of various concentrations of aqueous NaOH to the copolymer THF solutions. The hydrodynamic diameters of the particles obtained by the procedures were several hundreds of nanometer. When the azobenzene unit content in the copolymer was smaller, the diameters of the particles became smaller. When the colloidal particles dispersions were cast on a carbon sheet and dried, the particles aggregated and formed larger spherical particles, with diameters of several micrometers. The size of the particles obtained by the drying process became smaller, when higher concentrations of aqueous NaOH solutions were used. Therefore, the particle sizes were controlled by the azobenzene units content in the copolymers and the concentration of aqueous NaOH solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3913–3918, 2006