Synthesis, characterization, and gamma radiation effects over well‐defined poly(vinylsiloxanes) copolymers

Anionic ring‐opening polymerization (AROP) was employed for the controlled synthesis of linear model block copolymers of 1,3,5,7‐tetrametil‐1,3,5,7‐tetravinyl(cyclotetrasiloxane) (V 4 ) and 1,3,5‐dimethyl(cyclotrisiloxane) (D 3 ) monomers by using sec ‐butyl lithium ( sec ‐Bu − Li + ) as initiator, and high‐vacuum anionic polymerization techniques. V 4 copolymerization was promoted by employing D 3 and sec ‐Bu − Li + producing living silanolates that open the stable V 4 ring. For this purpose, two strategies were applied: (a) sequential addition of monomers, and (b) one‐step copolymerization at different reaction temperatures. According to the experimental results, higher levels of V 4 incorporation (∼ 18.14 mol %) were obtained by mixing both co‐monomers and performing the reaction at high temperature (80°C). This strategy allowed the control of the V 4 incorporation into the copolymer structure, giving the opportunity of synthesizing model vinyl‐siloxane polymers. The gamma radiation of these materials showed that lower doses are needed to achieve the same gel content as in a model poly(dimethylsiloxane) (PDMS). In such a sense, these results constitute one of the first reports regarding the effect of gamma radiation on vinyl‐containing silicon polymers, and may be of fundamental importance if a biomedical cross‐linked rubber‐type PDMS is needed at earlier doses of sterilization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012