Enhancement of mechanical and optical performance of commercial polystyrenes by blending with siloxane‐based copolymers

Well‐defined poly(styrene‐ block ‐dimethylsiloxane) copolymers (PS‐ b ‐PDMS) with low polydispersity index ( M w / M n ) and different compositions were synthesized by sequential anionic polymerization of styrene (S) and hexamethyl(ciclotrisiloxane) (D 3 ) monomers. Synthesized PS‐ b ‐PDMS copolymers were characterized by 1 H‐nuclear magnetic resonance, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron microscopy. The physicochemical characterization determined that block copolymers have molar mass values close to ∼135,000 g mol −1 , narrow M w / M n  < 1.3, and chemical composition ranging from low to intermediate PDMS content. Blends of these copolymers with a commercial polystyrene (PS) were obtained by melt mixing and subsequently injection. Films obtained were flexible, and showed lower transparency than the original PS matrix. On the other hand, a 10 wt % incorporation of PS‐ b ‐PDMS copolymers leads to better mechanical performance by enhancing elongation at break (∼8.8 times higher) and opacity values (∼18 times higher). In addition, UV–Vis barrier capacity of the resulting blends is also increased (up to 400% higher). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45122.