Gel formation and primary chain lengths in nitroxide-mediated radical copolymerization of styrene and divinylbenzene in miniemulsion

Abstract

Gelation in 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated cross-linking copolymerization of styrene and divinylbenzene (8.2 mol%) in aqueous miniemulsion at 125 C has been investigated. The rate of gel formation relative to monomer conversion was the same in miniemulsion and the corresponding solution polymerization when the organic phase contained 6 vol% tetradecane (TD; hydrophobe) and 48 vol% toluene. However, at 54 vol% TD and no toluene (the same total monomer concentration), the conversion at the gel-point was lower in miniemulsion than in solution, consistent with our previous results describing enhanced apparent pendant reactivity related to the presence of TD in the present system. The primary chain lengths were higher in miniemulsion with 54 vol% TD than in miniemulsion with 6 vol% TD and in solution (6 and 54 vol% TD). It was deduced via application of Flory-Stockmayer gelation theory that this difference in primary chain lengths, although significant with regards to gelation, was insufficient to explain the rapid gel formation in the miniemulsion containing 54 vol% TD, which is speculated to be related to specific effects of the heterogeneity of the miniemulsion system.

Time Programmed Feed of Semi‐Batch Reactors with Non‐Linear Radical Copolymerizations: An Experimental Study of the System Styrene + Divinylbenzene Using SEC/MALLS

“…methyl methacrylate þ ethylene glycol dimethacrylate) with suspected effects of spatial segregation of chemical groups. The extension of the present study to living or mediated non-linear systems [26] is another application with potential interest.…”

Polimerização RAFT em Miniemulsão

“…Conforme já revisado, as técnicas de CLRP [136] permite a síntese de polímeros com arquitetura molecular definida, tendo sido recentemente adaptada para uso em diversos tipos de sistemas dispersos de polimerização, o que torna possível o uso de diversas técnicas de CLRP como rota de síntese de nanogéis com arquitetura molecular complexa e definida [13,[137][138][139][140][141] . De uma forma geral, as técnicas de CLRP em sistemas dispersos são de fato rotas bem atrativas para a síntese de nano-hidrogéis com estrutura molecular bem definida (ex.…”

Miniemulsion polymerization based on in situ surfactant formation without high-energy homogenization: effects of organic acid and counter ion

“…[7][8][9][10][11][12][13][14] Miniemulsion polymerization is distinct from the more common emulsion polymerization technique with respect to the mechanism of particle formation. In miniemulsion polymerization, particles are formed via monomer droplet nucleation, whereas in emulsion polymerization, particle formation occurs in the aqueous phase via micellar and/or homogeneous nucleation.…”