Room-temperature decomposition of 2,2′-azobis(isobutyronitrile) in emulsion gels with and without silica

Low-temperature polymerization of methyl methacrylate emulsion gels through surfactant catalysis

“…The MMA system could be polymerized at a temperature much lower than normal thermally-initiated free radical polymerization [1,2], because the initiator, AIBN was complexed with surfactant through surfactant catalysis [10]. The decomposition of the initiator was also enhanced due to the presence of fumed silica [11]. However, the practical polymerization temperature for this system, was higher than that for a similar system with styrene (i.e., room temperature) [9].…”

“…Surfactant-catalyzed polymerizations at low temperatures were achieved by enhanced decomposition of AIBN when complexed with CTAB in emulsions. Consequently, the temperatures needed for AIBN decomposition are significantly lowered, even as low as room temperature [11,12]. The gelation in the emulsions caused by adding fumed silica particles could further enhance the decomposition for AIBN, but fumed silica alone did not affect the initiator decomposition [11].…”

“…Consequently, the temperatures needed for AIBN decomposition are significantly lowered, even as low as room temperature [11,12]. The gelation in the emulsions caused by adding fumed silica particles could further enhance the decomposition for AIBN, but fumed silica alone did not affect the initiator decomposition [11]. Although MMA could be polymerized with AIBN at room temperature in emulsion gels, 40°C was needed to obtain uniform PMMA/silica/CTAB composites.…”

“…Free radical polymerizations at low temperatures also showed narrower polydispersities [4,5], different tacticities [6], and structures compared with higher temperature polymerizations. Conducting free radical polymerizations at low temperatures is important, and can be achieved by using metallic catalysts [7], redox initiators [8], irradiation [4], or, more recently, emulsion gels [9][10][11]. It is the later which is the focus of this work.…”

“…Kinetics data from the cationic surfactant, cetyltrimethylammonium bromide (CTAB) and AIBN system suggested that the AIBN and CTAB formed a complex [10], which accelerates the decomposition of AIBN. Therefore, it is possible to conduct the free radical polymerization at lower than normal temperatures [9,11]. For example, emulsion gels containing 90% of styrene monomers were polymerized at 21°C in 24 h through CTAB catalysis, and mono-dispersed polystyrene(PS)/CTAB/silica nanoparticles were obtained [9].…”