Kinetics and colloidal parameters of miniemulsion polymerization of butyl acrylate

Abstract

AbstractBACKGROUND: The miniemulsion polymerization of butyl acrylate initiated by a macromonomeric azoinitiator (macroinimer, MIM) and stabilized by the non‐ionic emulsifier Tween 60 (TW‐60) was investigated.RESULTS: The monomer conversion and the polymerization rate increase with the amount of MIM and then decrease. The desorption rate constants were estimated using the Ugelstad/O'Toole, Gilbert and Nomura models. The Ugelstad/O'Toole and Gilbert models suggest an increase in the k′des value with increasing emulsifier concentration at the highest MIM concentration while the Nomura model proposes no variation in k′des with an increase in both TW‐60 and MIM concentrations. The polymerization rate increases in the following order with regard to initiator: MIM < ammonium persulfate < dibenzoyl peroxide < 2, 2′‐azobisisobutyronitrile.CONCLUSION: The increase in the rate of polymerization can be discussed in terms of both increased particle concentration and the gel effect. The size of the polymer particles decreases and the number of polymer particles increases with both TW‐60 and MIM concentrations. This behaviour is attributed to the formation of a larger number of smaller monomer and/or polymer particles and higher particle nucleation rate. The observed long nucleation period for the MIM‐initiated polymerization is attributed to the creation of a crosslinked structure and the immobilization of MIM chains. Copyright © 2009 Society of Chemical Industry