Effect of stirring rate on particle formation in emulsifier-free, organotellurium-mediated living radical emulsion polymerization (emulsion TERP) of styrene

Abstract

Particle formation during the initial stages of emulsifier-free organotellurium-mediated living radical emulsion polymerization (emulsion TERP) of styrene at 601C was investigated at two stirring rates (220 and 1000 r.p.m.), in which the styrene phase floated as a layer on an aqueous phase at 220 r.p.m. or became dispersed as droplets at 1000 r.p.m. A water-soluble TERP agent, poly(methacrylic acid) (PMAA)-methyltellanyl (PMAA 30 -TeMe) and a water-soluble thermal initiator, 4,4¢-azobis(4-cyanovaleric acid), at alkaline pH were used. The control/livingness was better at 1000 r.p.m. than at 220 r.p.m., and the particle size distribution was also affected by the stirring rate: both nanometer-sized and submicrometer-sized particles were observed at 220 r.p.m., and mainly nanometer-sized particles were observed at 1000 r.p.m. Because the percentage of PMAA 30 -TeMe consumed in the initial stage was much higher at 1000 r.p.m. than at 220 r.p.m., self-assembly nucleation preferentially occurred at 1000 r.p.m., resulting in nanometer-sized particles and good control/livingness. Stirring at 1000 r.p.m. only in the initial stage of the emulsion TERP followed by 220 r.p.m. induced good control/livingness and the formation of mainly nanometer-sized particles. It is concluded that a high stirring rate in the initial stage is important for the emulsion TERP of styrene to obtain good control/ livingness and to control the particle formation mechanism.

Size Control of Polymeric Particle in Soap-Free Emulsion Polymerization

“…To study the effect of the concentration of V-501, C i , on particle properties, SFEPs of styrene were carried out changing C i at the constant concentrations of styrene monomer and AIBN. The reason why V-501 was selected was that the particles were synthesized in the SFEP using watersoluble initiator with carboxyl groups at high pH because of ionized initiator radicals derived from the initiators (Gu S. et al, 2004;Moribe H. et al, 2011;Yamada Y. et al, 2005). It was confirmed that the particles were not able to be formed independently by V-501 in normal water.…”

A synthetic route to ultra-high molecular weight polystyrene (>106) with narrow molecular weight distribution by emulsifier-free, emulsion organotellurium-mediated living radical polymerization (emulsion TERP)

“…3 wt%) with one order smaller concentration (0.25 mM) of the water-soluble macro-chain transfer agent compared to the emulsion RAFT systems discussed above. [33][34][35][36] Fig. The particle nucleation step is a critically important one in the emulsion polymerization system.…”

“…[25][26][27] The possible reversible activation processes of TERP are degenerative chain transfer (DT) and thermal dissociation (TD) mechanisms, in which the TD can be negligible below 100°C (Scheme 1). [29][30][31][32][33][34][35][36][37][38] Styrene, acrylates, and methacrylates were used in the emulsion TERP to prepare these polymer particles having a narrow MWD. 28 In our previous work, TERP was successfully applied to an emulsifier-free emulsion polymerization system (emulsion TERP) with poly(methacrylic acid)-methyltellanyl (degree of polymerization of PMAA: 30) (PMAA 30 -TeMe), with the synthesis of well-controlled homopolymers and block copolymers via the DT mechanism.…”

Soap-free emulsion polymerization of poly (methyl methacrylate-co-butyl acrylate): effects of anionic comonomers and methanol on the different characteristics of the latexes

“…The consequences of the former and the latter are increase and decrease in particle size, respectively. Regardless of these points, the existence of monomer droplets in SFEP is accompanied by some difficulties such as sensitivity of particle size and particle size distribution on the agitation speed [12, 13], and chemical chain heterogeneity in production of copolymers [14]. Utilizing ethanol as co-solvent, Lio et al [10] restricted the formation of free polyelectrolyte chains and adjusted particle size.…”