Microemulsion polymerization of styrene using a polymerizable nonionic surfactant and a cationic surfactant |
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Authors: | X J Xu K S Siow M K Wong L M Gan |
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Institution: | (1) Department of Chemistry National University of Singapore 10 Kent Ridge Crescent Singapore 119260, Singapore, SG;(2) Institute of Materials Research and Engineering, 3 Research Link Singapore 117602, Singapore e-mail: lm-gan@imre.org.sg Tel.: +65-874-5250; Fax: +65-872-0785, SG |
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Abstract: | High polymer/surfactant weight ratios (up to about 15:1) of polystyrene microlatexes have been successfully produced by microemulsion
polymerization using a small amount of polymerizable surfactant, ω-methoxypoly(ethylene oxide)40 undecyl α-methacrylate macromonomer (PEO-R-MA-40), and cetyltrimethylammonium bromide (CTAB). After generating “seeding particles”
in a ternary microemulsion containing only 0.2 wt% CTAB and 0.1 wt% styrene, the additional styrene containing less than 1 wt%
PEO-R-MA-40 was added dropwise to the polymerized microemulsion for a period of about 4 h at room temperature. PEO-R-MA-40
copolymerized readily with styrene. The stable microlatexes were bluish-transparent at a lower polymer content and became
bluish-opaque at a higher polymer content. Nearly monodisperse latex particles with diameters ranging from 50 to 80 nm and
their molar masses ranging from 0.6 to 1.6 × 106 g/mol could be obtained by varying the polymerization conditions. The dependence of the number of particles per milliliter
of microlatex, the latex particle size and the copolymer molar mass on the polymerization time is discussed in conjunction
with the effect of the macromonomer concentration.
Received: 25 October/2000 Accepted: 2 February 2001 |
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Keywords: | Microemulsion polymerization Styrene Polymerizable nonionic surfactant Macromonomer |
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