Solvation effect in the thermal decomposition of 2,2?-azoisobutyronitrile in the three-component system

Abstract

The thermal decomposition rate constant (kd ) of 2,2′‐azoisobutyronitrile in acrylonitrile (AN; monomer A)–methyl methacrylate (MM; monomer B) comonomer mixtures in N,N‐dimethylformamide (DMF) as a function of the comonomer mixture composition and its concentration in the solvent at 60 °C was studied. The dependences kd = f(xA ,C) [xA (mole fraction of A in the comonomer mixture) = A/(A + B) = A/C, where C is the comonomer mixture concentration] have a different course as a function of C: from a curve kd = f(xA ) approaching the straight line (C = 2 mol · dm−3) to a convex curve possessing a maximum at a point xA = 0.7 (C = 4 mol · dm−3) to a curve with a flattened wide maximum within the range of xA = 0.2–0.8 (C = 7 mol · dm−3) to a curve with the shape of a lying s (C = 9 mol · dm−3). All the courses of the experimental dependences kd = f(xA ,C) can be explained with a hypothesis of initiator solvation by the comonomers AN and MM and the solvent DMF. The existing solvated forms, their relative stability constants, the thermal decomposition rate constants, and the relative contents in the system were determined. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2156–2166, 2000

Kinetic study of the free‐radical polymerization of vinyl acetate in the presence of deuterated chloroform by 1H‐NMR spectroscopy

“…This dependence was not a linear function from the VAc molar fraction. The same results have been reported for the k d of AIBN in various solvent/monomer mixtures, such as N,N ‐dimethylformamide (DMF)/methyl methacrylate (MMA),27 DMF/acrylonitrile (AN),28, 29 and DMF/MMA/AN30 at 60°C. The dependence of the k d of AIBN on the solvent concentration (or equivalent [M]) has been interpreted on the bases of the hypothesis of initiator solvation by the monomer and solvent alone and by the mixed monomer/solvent 29, 31…”

Polymerization of acrylonitrile in the presence of functional azo-initiator 2,2'-azobis[2-methyl-omega-hydroxy-oligo(oxyethylene) propionate]

“…Konse-kwencj¹ wystêpowania w badanym oerodowisku AN/DMF azoinicjatora AIB-OOE(400) w postaci solwatów MIM, SIS i MIS jest fakt, ¿e w reakcji inicjowania polimeryzacji bior¹ udzia³ rodniki powsta³e z rozpadu tych wszystkich trzech postaci solwatacyjnych. Mechanizm procesu inicjowania mo¿na wiêc opisaae trzema reakcjami rodników pierwotnych - [11]. Te reakcje inicjowania charaktery-zuj¹ siê w³asnymi szybkooeciami, odpowiednio,…”

Functional azo-initiators - thermal decomposition in acrylonitrile/N,N-dimethylformamide mixtures

“…W modelu solwatacji inicjatora monomerem i rozpuszczalnikiem [11,13] [14]; t, p, n, lexperimentally determined values; equations (5)- (8)…”

“…Jednym z etapów inicjowania jest rozpad termiczny inicjatora. Zale¿nooeae sta³ej szybkooeci rozpadu ró¿nych inicjatorów od sk³adu mieszaniny reakcyjnej by³a przedmiotem badañ opisanych przez nas w tej publikacji i w wielu poprzednich [13,14].…”

“…Postacie solwatacyjne w roztworze AIB-OOE(400) charakteryzuj¹ siê wiêkszymi wartooeciami sta³ych stabilnooeci ni¿ w roztworach pozosta³ych azoestrów. Cz¹steczki AIB-OOE(400) s¹ silnie solwatowane przez roz- [14].…”