title: Room-temperature decomposition of 2,2'-azobis(isobutyronitrile) in emulsion gels with and without silica.
abstract: The decomposition of 2,2'-azobis(isobutyronitrile) (AIBN) at room temperature was studied in emulsion gels, with and without silica, using UV/visible spectroscopy. The emulsion gels consisted of toluene, AIBN, an aqueous solution of a surfactant (either hexadecyltrimethylammonium bromide, CTAB, or sodium dodecyl sulfate, SDS), and, in some cases, fumed silica. The AIBN compositions were determined in the opaque emulsion gels by converting them to transparent microemulsions. The decomposition rate constants for AIBN were determined to be 3.7 x 10(-8) s(-1) (+/-0.6 x 10(-8) s(-1)) for the emulsion gels and 10.2 x 10(-8) s(-1) (+/-1.3 x 10(-8) s(-1)) for the silica-containing emulsion gels. These rate constants were significantly greater than that in toluene solution, which, by our technique, is below our measurement threshold (effectively 0).
authors.affiliation: Department of Chemistry and Materials Research Center, University of Missouri-Rolla, Rolla, MO 65409-0010, USA.
authors.forename: Gu
authors.initials: G
authors.lastname: Xu
authors.forename: Rakesh R
authors.initials: RR
authors.lastname: Nambiar
authors.forename: Frank D
authors.initials: FD
authors.lastname: Blum
mesh_terms: D004655:Emulsions / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D009570:Nitriles / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D004655:Emulsions; D005782:Gels; D009570:Nitriles; D012822:Silicon Dioxide; C004526:azobis(isobutyronitrile)