GLASS-TRANSITION OF ADSORBED STEREOREGULAR PPMA BY INVERSE GAS-CHROMATOGRAPHY AT INFINITE DILUTION

In this paper, we used inverse gas chromatography (IGC) at infinite di lution that proved to be a powerful technique to determine glass trans ition and other transitions of PMMA adsorbed on a-alumina. We highligh ted the glass transition temperature of the system PMMA/alpha-Al2O3 wi th defined polymer tacticity at various covered surface fractions. Thu s, the Tg of the adsorbed isotactic PMMA increases strongly as compare d to the bulk value. The study of the physical chemical properties of PMMA/alpha-alumina revealed an important difference in the acidic and basic behaviour, in Lewis terms, of aluminium oxide covered by various concentrations of PMMA. It appears that there is a stabilisation of t he physical chemical properties of PMMA/alpha-Al2O3 for a surface cove rage above 50 %. This study also highlighted an important effect of th e tacticity of the polymer on the acid-base character of the system PM MA/Al2O3.