Cover: Different morphological aspects of poly(vinyl acetate) particles produced through suspension polymerization are shown. When produced by conventional free radical polymerization, final particles present an irregular oval morphological aspect, due to combination of the high shear rates and high reaction rates. When small amounts of the RAFT chain transfer agent are used, final particles present the usual spherical morphology of beads produced in suspension, due to the lower reaction rates and consequently longer relaxation times to dissipate shear tensions. Further details can be found in the article by M. Oliveira, B. S. Barbosa, M. Nele, and J. C. Pinto* http://doi.wiley.com/10.1002/mren.201300175.

Suspension and bulk polymerizations of vinyl acetate (VAc) are performed in several experimental conditions, using cyanomethyl methyl(phenyl) carbamodithioate as the chain transfer agent (CTA). The polymerization kinetics are monitored in batch for bulk polymerizations, showing an inhibitory period at the beginning of the reaction runs, despite the particular experimental conditions used. More accurate control over the molecular properties of the synthesized poly(vinyl acetate) (PVAc) is achieved when high concentrations of CTA are used. Similar experimental conditions are applied to prepare PVAc particles via suspension polymerization of VAc in the presence of small amounts of CTA. It is possible to produce spherical particles with a narrow particle size distribution and predominant spherical morphology. Although the reactions yield low control over the molecular weight properties, it is possible to use the synthesized particles as macro-CTAs and promote chain extension reactions to extend the chain length of the PVAc.