Influence of n‐dodecyl mercaptan as chain transfer agent in dispersion polymerization of styrene

Abstract

Dispersion polymerization of styrene with n‐dodecyl mercaptans (DDM) as the chain transfer agent was investigated. PS particles with various molecular weight, molecular weight distribution (MWD), and particle diameter were prepared by varying the concentration of DDM and also the addition time of DDM before and after the particle nucleation. The average particle diameter was increased, whereas polymerization rate, molecular weight, and MWD were decreased with increasing DDM concentrations from 0 to 10 wt %. The effect of addition of DDM before and after particle nucleation was studied at 0.4, 0.8, and 1.0 wt % DDM. The addition of DDM before particle nucleation produced PS particles of relatively large particle diameter and low molecular weight when compared with the addition of DDM after particle nucleation. This study shows that particle nucleation occurs in about 5–6 min, which corresponds to the 15–16% conversion, 372–378 nm in Dn, and provides a facile way to control the particle size and interesting information about the particle formation using the delayed addition of DDM. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6612–6620, 2008

Highly crosslinked micron‐sized, monodispersed polystyrene particles by semicontinuous dispersion polymerization. II. Semicontinuous, delayed addition and seeded semicontinuous processes

“…This corresponds to a conversion of 15-16%. 15 However, the results obtained by the delayed addition do not follow the 15-16% as shown in Table V. When 0.35 wt % of the DVB was added between15 and 180 m (conversion: 19-38%) after the start of the polymerization, polydispersed and smooth-surfaced particles were observed [ Fig.…”

“…Dispersion polymerization [10][11][12][13][14][15] is an important polymerization method to prepare monodispersed micron-sized polymer particles. However, when the crosslinking agent was used in the dispersion polymerization some problems 5,13,14,16,17 have encountered, including loss of control of particle size, broadening of the size distribution, odd-shaped particles, and coagulation of the polymer particles in the reaction.…”