Thermodynamic characteristics of poly(cyclohexylethylene-b-ethylene- coethylethylene) block copolymers

A series of poly(cyclohexylethylene-b-ethylene-coethylethylene) (C-E/E _E) diblock copolymers containing approximately 50% by volume glassy C blocks and varying fraction (x) of E_E repeat units, 0.07 ≤ x ≤ 0.90, was synthesized by anionic polymerization and catalytic hydrogenation. The effects of ethyl branch content on the melt state segment-segment (v) interaction parameter and soft (E/E_E) block crystallinity were studied. The percent crystallinity ranged from approximately 30% at x = 0.07 to 0% at about x ≥ 0.30, while the melting temperature changed from 101 °C at x = 0.07 to 44 °C at x = 0.28. Dynamic mechanical spectroscopy was employed to determine the order-disorder transition (ODT) temperatures, from which v was calculated assuming the mean-field prediction ( _χN_n)_ODT = 10.5. Previously published results for the temperature dependent binary interaction parameters for C-E (x = 0.07), C-E_E (x = 0.90), and E-EE (x = 0.07 and x = 0.90) fail to account for the quantitative x dependence of χ, based on a simple binary interaction model.