Statistical copolymer

An ideal dilution estimate for a random copolymer whose comonomer units are excluded from the crystal. Let $x$ be the crystallizable-unit fraction in the melt and $\Delta h_f$ the molar enthalpy of fusion per such unit. Mixing contributes $RT\ln x$ to its liquid chemical potential. Approximate the unmixed liquid-minus-solid chemical-potential difference by $\Delta h_f(1-T/T_m^0)$. Equating the sum to zero gives the displayed relation. For $x<1$, the predicted melting temperature decreases. Nonideal mixing, finite crystallizable sequences, lamellar surface energy and comonomer inclusion can change the result.

A copolymer containing $-\mathrm{C}{\mathrm{H}}_2-\mathrm{CHCl}-$ and $-\mathrm{C}{\mathrm{H}}_2-\mathrm{CH}(\mathrm{OH})-$ units. It describes the intended chemical composition, not a guarantee that unselective alkaline treatment yields an undegraded polymer.

A copolymer containing $-\mathrm{C}{\mathrm{H}}_2-\mathrm{CHCl}-$ and $-\mathrm{C}{\mathrm{H}}_2-\mathrm{CH}(\mathrm{OAc})-$ units. Hydrolysis changes the acetate side groups without requiring cleavage of the carbon backbone, provided competing degradation is controlled.

Alkaline conditions that hydrolyse acetate side groups can also promote elimination from chlorinated backbone units. Dechlorination, unsaturation, changed solubility and possible subsequent cross-linking complicate isolation of an ideal vinyl chloride-vinyl alcohol copolymer. The competition is condition-dependent: analytical work used staged treatment and precipitation to restrain dehydrochlorination, so difficulty under generic conditions is not a proof that every hydroxyl-containing chloride copolymer is impossible.^[ref]

A copolymer with an ideal sequence in which the probability of a monomeric unit is independent of neighbouring units. A real copolymer made by concurrent radical reactions can have sequence correlations; a feed ratio does not by itself establish incorporated composition or independent-unit statistics.