On the evolution of the rate of polymerization, number and size distribution of particles in styrene emulsion polymerization above CMC

Abstract

This work is an extension of a communication reported by two of the authors [Carro and Herrera-Ordoñ ez, Macromol Rapid Commun 2006, 27, 274], where bimodal particle size distributions (PSD), obtained by asymmetric flow-field flow fractionation (AFFF, AF 4 ), were taken as evidence of certain degree of stability of primary particles. Now, emulsion polymerizations of styrene were performed under conditions employed before by other researchers, intending to examine if the behavior observed is general. The number of particles (N) and PSD were studied by means of dynamic light scattering and AF 4 . By the later, bimodal PSDs were detected in all cases, where the population corresponding to primary particles (diameter <20 nm) depends on reaction conditions. Regarding N, AF 4 results show that it is constant during interval II, in contrast to DLS results. Primary particle coagulation was evidenced as minimums in N evolution and the rate of polymerization curves, monitored by calorimetry and gravimetry, which are enhanced when higher particle number is generated and/or the ionic strength is increased. These results suggest that particle coagulation is not as extensive as it would be expected according to the coagulative theory. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [3152][3153][3154][3155][3156][3157][3158][3159][3160] 2010

Synthesis of Sub-100 nm and Narrow Particle Size Distribution Cationic Latex by One-Step Emulsion Polymerization

“…This profile was attributed to the effect of surfactant concentration on particle nucleation, as shown in Fig. 4, that is, the nucleation period would be prolonged as the surfactant concentrations increased, resulting in the particle number increased, furthermore, the polymerization rate enhanced, which is similar to the investigation of Carro et al [26] The evolutions of particle size distribution as a function of monomer conversion or reaction time for the emulsion polymerization with different surfactant concentrations were shown in Fig. 6.…”

Rheological Properties in Aqueous Solution for Hydrophobically Modified Polyacrylamides Prepared in Inverse Emulsion Polymerization

“…This behavior has been observed in styrene emulsion polymerization and was attributed to limited particle coagulation causing an apparent change in radical concentration, leading to bimolecular termination [33,34]. In our case, for an increase in initial monomer concentration, [ 0 ], a greater number in droplets is expected; however, for the same surfactant concentration, droplet degradation can take place via coalescence, or particle coagulation occurs because of a lack of surfactant to stabilize the system.…”

Facile synthesis of large scale and narrow particle size distribution polymer particles via control particle coagulation during one-step emulsion polymerization

“…3 × 10 17 per unit mass aqueous phase) during 10-30 min, and the average particle diameter increased from 50 to 85 nm, indicating that obvious particle coagulation occurs in this period. The graph of monomer conversion vs. reaction time provides some extra information about the time of particle coagulation, indicating that particle coagulation lasted for only a very short interval ranged in monomer conversion from 0.13 to 0.21; in contrast, combined with the evolution of the average particle size and number, particle coagulation occurred during the particle nucleation (classical nucleation interval ranged in monomer conversion from 0 to 0.15 [25][26][27]). Thus, the formation of new particle formed in the nucleation period is a major problem in determining particle coagulation feature, thus increasing the particle number and decreasing the average particle size.…”