Thermodynamic Characteristics of Poly(cyclohexylethylene-$b$-ethylene-\textit{co-}ethylethylene) Block Copolymers

A series of poly(cyclohexylethylene-$b$-ethylene-\textit{co-}ethylethylene) (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 $\le \quad x \quad \le $ 0.90, was synthesized by anionic polymerization and catalytic hydrogenation. The effects of ethyl branch content on the melt state segment-segment (\textit{$\chi $}) interaction parameter and soft (E/E$_{E})$ block crystallinity will be presented. The percent crystallinity ranged from approximately 30{\%} at $x$ = 0.07 to 0{\%} at about $x \ge $ 0.30, while the melting temperature changed from 101 \r{ }C at $x$ = 0.07 to 44 \r{ }C at $x =$ 0.28. Dynamic mechanical spectroscopy was employed to determine the order-disorder transition (ODT) temperatures, from which \textit{$\chi $} was calculated assuming the mean-field prediction (\textit{$\chi $N}$_{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-E$_{E}$ ($x$ = 0.07 and $x $= 0.90) fail to account for the quantitative $x$ dependence of $\chi $, based on a simple binary interaction model.