The control of the glass transition temperature (T-g) in functionalized polymers is crucial for materials engineering and pharmaceutical applications. Tailoring must overcome experimental and theoretical issues regarding the thermodynamical phenomena involved. In this work, we study the glass transition of poly(monoitaconate)s and poly(diitaconate)s systems functionalized by internal plasticization. Differential scanning calorimetry (DSC) and Raman spectroscopy are used to determine T-g, whereas thermal degradation analysis (TGA) is used to determinate the temperature limit where conformers relax independently, defined as T* in the Adams-Gibbs model. Our results show that the values of T-g, obtained through DSC and Raman are consistent and that TGA can be used to estimate a lower bound limit for T*. We mainly conclude that a larger steric hindrance between the carboxylic group in the side chain and the backbone increases T-g and decreases the variation of specific heat and configurational entropy at different domain regions. Similar behavior is observed when chlorine atoms are substituted in the phenethyl groups. (C) 2014 Elsevier B.V. All rights reserved.