“…The situation is different in random copolymers where a single glass temperature is commonly anticipated. Indeed, many random copolymers were investigated with differential scanning calorimetry (DSC), − rheology, − ,,− dielectric spectroscopy (DS), ,,, ellipsometry, , molecular dynamics simulations, and theory. There is now a vast literature on the composition dependence of glass temperature in such systems. As an example, a single study reported a data set comprising more than 400 glass temperatures of several random copolymers with glass temperature difference of pure components, Δ T g , ranging from 1 to 165 K. The composition dependence of the glass temperatures in random copolymers has been discussed in terms of the Gordon and Taylor or the DiMarzio and Gibbs equations that assume respectively volume additivity of the repeat units and additivity of “flexible” bonds, thus emphasizing packing vs intermolecular effects.…”