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Effect of cationic surfactant on homogenization and polymerization of methyl methacrylate miniemulsion modified by chitosan
Author(s) -
Jeng Jauder,
Dai ChiAn,
Chiu WenYen,
Young PinYen
Publication year - 2007
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2199
Subject(s) - miniemulsion , nucleation , polymerization , cationic polymerization , chemical engineering , methyl methacrylate , materials science , polymer chemistry , monomer , chitosan , coalescence (physics) , pulmonary surfactant , chemistry , composite material , organic chemistry , polymer , physics , astrobiology , engineering
Homogenization of monomer droplets and polymerization of methyl methacrylate (MMA) miniemulsion, stabilized by a combination of cationic surfactants including different amounts of n ‐hexadecyltrimethylammonium chloride (HTMA) and chitosan 100, were investigated. With increasing HTMA concentration or decreasing concentration of chitosan 100, the required ultrasonication time for the miniemulsion to reach a critically stabilized state is reduced. After polymerization, for higher HTMA concentrations, droplet nucleation dominates because of higher surface coverage of HTMA on the droplets. However, for lower HTMA concentrations, the size distributions (SDs) of final latex particles are different from those of the droplets. Because surface coverage of HTMA on the droplets is lower in this condition, both droplet nucleation and homogeneous and/or micellar nucleation occur simultaneously in the miniemulsion polymerization. On increasing the concentration of chitosan 100 in the system, the SD of the final latex particles is far different from that of the droplets. This is due to a decrease of the effective surface coverage of chitosan 100 and HTMA on the droplets. Consequently, the opportunity of collision coalescence of the droplets increases, and MMA molecules can diffuse out more easily into the aqueous phase. Droplet nucleation is, therefore, no longer the major source for the latex particles. Copyright © 2006 Society of Chemical Industry