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

Abstract

ABSTRACTWell‐defined poly(styrene‐block‐dimethylsiloxane) copolymers (PS‐b‐PDMS) with low polydispersity index (Mw/Mn) and different compositions were synthesized by sequential anionic polymerization of styrene (S) and hexamethyl(ciclotrisiloxane) (D3) monomers. Synthesized PS‐b‐PDMS copolymers were characterized by 1H‐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 Mw/Mn < 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.