Does the Glass Transition of Polymers Change Upon 3D Confinement?

The calorimetric trace of polymer spheres shows an increase of the glass‐transition temperature ( T g ), with respect to its bulk value. This increase is evaluated by means of an entropy model, where the 3D confinement leads to a limiting number of repeating polymer units in the sphere, and thus to a reduction of the possible configuration states of the polymer chains. This is ultimately related to variations in the bulk value of the T g . Also, the way the polymer nature affects how confinement takes place and how restrictions imposed affect the way a polymer forms cooperative rearranging regions at T g are presented.