The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state.

In the current climate of growing environmental concerns, especially taking into consideration the finite nature of global petroleum resources, biobased polymers are synthetic targets of great interest. In particular, the polyurethane industry is demanding high biobased containing polyols in their raw materials portfolio. While most of the biobased polyols are based on polyesters, the majority of industrial polyurethanes are prepared using polyether polyols due to their low glass transition temperature, T g, and higher chemical resistance. In this work, we report a series of fully biobased copolyether polyols with low T g and tunable melting temperatures prepared from the self-condensation of two biobased diols, 1,4-cyclohexanedimethanol and 1,6-hexanediol. By increasing the 1,4-cyclohexanedimethanol content, copolyethers with lower melting temperatures (<50 °C) and degrees of crystallinity are obtained while still showing low T g values (←40 °C). We also find that the conformation of the 1,4-cyclohexanediol strongly influences the way in which these random copolyethers crystallize. Thus, when 100% trans isomer on 1,4-cyclohexanediol is used, the copolymers show isodimorphic crystallization behavior, showing semicrystalline behavior for all compositions. However, when the cis content is at least 30%, comonomer exclusion occurs and above 50 mol % of 1,4-cyclohexanediol the polyether is fully amorphous. This polycondensation route shows a simple and sustainable way to synthesize fully biobased polyether polyols with comprehensive properties and tunable crystallinity which make them ideal candidates for the preparation of a great variety of polyurethane elastomers.

Photoinduced polymerization is a useful tool in many industrial applications such as coatings, adhesives and 3D printing. However, the use of light to promote polymerization has been almost exclusively used...