Effect of 1-pentanol on the styrene emulsion polymerization

The influence of 1-pentanol (C₅OH) on the ST emulsion polymerization mechanisms and kinetics is investigated. The CMC of the ST emulsions first decreases rapidly and then levels off when the C₅OH concentration (C₅OH]) increases from 0 to 72 mM. The effect of C₅OH increases to a maximum and then decreases when the SDS concentration (SDS]) increases from 2 to 18 mM. At SDS]=2 mM, homogeneous nucleation controls the polymerization kinetics regardless of C₅OH]. At SDS]=4 mM, the effect of C₅OH] appears due to the transition from homogeneous nucleation to a mixed mode of particle nucleation (homogeneous nucleation and micellar nucleation) occurs when C₅OH] increases from 0 to 72 mM. The effect of C₅OH] is the strongest at SDS]=6 mM since the particle nucleation mechanisms span homogeneous nucleation (low C₅OH]), a mixed mode of particle nucleation (homogeneous nucleation and micellar nucleation) (medium C₅OH]) and micellar nucleation (high C₅OH]). At SDS] >6 mM, in which micellar nucleation controls the polymerization kinetics, the effect of C₅OH] decreases rapidly with increasing SDS].