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Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates
Thermodynamic Behavior Of Poly(Cyclohexylethylene) In Polyolefin Diblock Copolymers, Eric W. Cochran, Frank S. Bates
Eric W. Cochran
We report the temperature dependence of the Flory-Huggins interaction parameter for three symmetric diblock copolymer systems containing poly(cyclohexylethylene) (PCHE): poly(cyclohexylethylene-b-ethylene) (CE), poly(cyclohexylethylene-b-ethylethylene) (CEE), and poly(cyclohexylethylene-b-ethylenepropylene) (CP). Order-disorder transition temperatures (TODT) were determined using dynamic mechanical spectroscopy and interpreted with mean-field theory, (χN)ODT = 10.5, leading to well-defined expressions for χ(T). These results have been analyzed in the context of solubility parameter (δ) theory resulting in a unique parameter δC that describes the interactions in CE, CP, and CEE, where δC < δEE < δP < δE with (δE - δC) ≈ 1.6 MPa1/2 at 500 K. In contrast to the predictions of group contribution theory, this indicates that δC is in surprisingly close proximity to the solubility parameter for poly(dimethylsiloxane).