Synthesis and Thermodynamic Properties of Poly(cyclohexylethylene-b-dimethylsiloxane-b-cyclohexylethylene)

Poly(styrene- b -dimethylsiloxane- b -styrene) (PS−PDMS−PS) triblock copolymers were prepared by anionic polymerization and subsequently hydrogenated using a platinum/rhenium catalyst supported on ultrawide pore silica (Pt/Re−SiO 2 ), yielding PCHE−PDMS−PCHE, where PCHE refers to poly(cyclohexylethylene). The hydrogenation reaction resulted in polymer with negligible chain degradation as confirmed by 1 H NMR and size exclusion chromatography (SEC). Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) experiments revealed a lamellar morphology for all specimens. Thermodynamic properties were inferred from the order−disorder transition temperatures as determined by SAXS and dynamical mechanical spectroscopy (DMS). The resulting segment−segment interaction parameter, χ( T ), is assessed in the context of current published approaches to treating the thermodynamics of nonpolar polyolefins, particularly block copolymers.