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4703395 
Journal Article 
Preparation of Poly(styrene-co-butadiene) Fine Latex via a Gemini Surfactant-Induced Low-Temperature Initiation Semibatch Emulsion Polymerization System 
Wang, Hui; Chan, E; Bregu, S; Rempel, GL 
2016 
Yes 
Journal of Polymer Science. Part A, Polymer Chemistry
ISSN: 0887-624X
EISSN: 1099-0518 
54 
12 
1669-1678 
WOS:000380037200001 
A series of SBR nanoparticle latexes were successfully synthesized using a semibatch emulsion polymerization system using GS 12-3-12 as the emulsifier. GS 12-3-12 is the key factor that governs the stabilization of the emulsion produced and the efficient initiation system at the lower temperature. Initiation and polymerization were carried out at a low reaction temperature of 25 degC, in which the decomposition rate of initiator APS was increased considerably by the acid catalysis in the strong acidic initiation environment created by GS 12-3-12. The pH values of SBR latexes produced were found to be in the range of 3 to 4. The polymerization conversions of SBR latex was controlled at 70 6 5 wt % within 25 h and no crosslinking was found in the SBR sample obtained. The solid content of the final latex product can be managed through using different monomer/water ratios and a solid content of up to 23.8 wt % can be reached. The particle diameter can be controlled by the surfactant concentration and monomer/water ratio. It was found that the particle size decreases with an increasing amount of surfactant. The TEM shows that the produced latex nanoparticles exhibit a spherical morphology. The SBR latex with Z-average diameter below 50 nm with a narrow near-monodisperse and monomodal distributions can be achieved with a quite low ratio of surfactant/monomer and surfactant/water surfactant/ monomer. FTIR, 1H NMR, and 13C NMR demonstrate that the St and BD units have been incorporated into the produced SBR. The contents of microstructure and composition were 23.8 wt % St, 10.4 wt % 1,2-vinyl and 65.8 wt % 1,4-structures of the BD which is constituted by the 46.6 wt % trans1, 4 and 19.2 wt % cis-1,4 configurations. The work reported here extends the ability to prepare polymer latexes with a new form of initiation system, which can be used to prepare a great variety of other polymer latexes. In addition, this polymerization process can considerably decrease the production investment allocated to the heating/cooling cost, which thereby shows substantial promise for commercial production in the future. 
emulsion polymerization; low-temperature initiation; particle nucleation; styrene butadiene rubber; Surfactants