Semibatch anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsions: effect of the amount of seed polymer particles

Authors


Correspondence to: Urška Šebenik,

University of Ljubljana, Faculty of Chemistry and Chemical Technology,

Aškerčeva cesta 5, 1000,

Ljubljana, Slovenia.

E-mail: urska.sebenik@fkkt.uni-lj.si

Abstract

Semibatch anionic ring-opening polymerization of octamethylcyclotetrasiloxane with the use of seed polymer particles in emulsions was studied. The concentration of the emulsifier was set above the critical micelle concentration. We investigated the effect of the amount of seed polymer particles on the chemical kinetics and the average particle size and distribution. During monomer starving conditions the polymerization rate strongly depended on the monomer feed rate and not on the amount of seed particles. Throughout the entire monomer feed period the average particle size increased. This increase depended on the number and the size of seed particles. In emulsions with higher particle sizes higher equilibrium conversions were obtained. In our opinion, a greater extent of backbiting reactions is responsible for lower equilibrium conversions during and at the end of the process. The seeded semibatch process seems a reasonable choice for designing emulsion products with high monomer conversion and desired particle size. © 2012 Society of Chemical Industry

Ancillary