AbstractThe values of the vitreous transition temperature,Tg, of three poly(methacrylic ester)s having bulky side groups are correlated with structural effects.Tghas been obtained experimentally by means of differential calorimetry and by the tensiometric method suggested byFerroni. The experimental values ofTgagree well with the calculated ones obtained by the method ofVan Krevelen. The values ofTgdetermined by differential calorimetry are markedly affected by the heating rate and by the molecular weight of the fractions.The solubility parameters of the polymers studied have been estimated. Poly(p‐tert‐butylphenyl methacrylate), (BPh), exhibits higher values for the solubility parameter, the steric hindrance parameter σ and the glass transition temperatureTgthan poly(p‐tert‐butylcyclohexyl methacrylate), (BCy), and poly(neopentyl methacrylate), (NPe).These results have been interpreted in terms of intermolecular forces and steric hindrance effects, which would be greater in BPh than in BCy