Determination of the glass transition temperature of poly(styrene-co-divinylbenzene) by inverse gas chromatography

Inverse gas chromatography (i.g.c.) was used to characterize the supermolecular structure of modified, moderately crosslinked poly(styrene-co-divinylbenzene) (5–20 wt%) and to determine the interactions with normal alcohols (C₁C₆). For all copolymers a decrease of retention time with increasing molecular weight of alcohols from C₁ to C₃ followed by an increase for C₄ to C₆ alcohols was observed. It was found that with propanol or butanol the measured T_g values were close to those measured by d.s.c. The T_g values for poly(styrene-co-divinylbenzene) containing 5, 10 and 20 wt% divinylbenzene were: 102°C, 116°C and 133°C respectively. The highest alcohols (C₅ and C₆) acted as plasticizers and reduced the apparent T_g value. The relationship between the isosteric heat of adsorption and the number of carbon atoms in the alcohols was nonlinear with a minimum corresponding to butanol.