Molecular mobility in biodegradable poly(ε-caprolactone)/poly(hydroxyethyl acrylate) networks

Poly(ε-caprolactone)/poly(hydroxyethyl acrylate) networks have been investigated by thermally stimulated depolarization currents (TSDC) and differential scanning calorimetry (DSC). The introduction of hydrophilic units (HEA) in the system aiming at tailoring the hydrophilicity of the system results in a series of copolymer networks with microphase separation into hydrophobic/hydrophilic domains. Polycaprolactone (PCL) crystallization is prevented by the topological constraints HEA units imposed in such heterogeneous domains. Moreover, the mobility of the amorphous PCL chains is enhanced as revealed by the main relaxation process which becomes faster. The glass transition of PHEA-rich domains shifts to lower temperatures, as the total amount of PCL in the copolymer increases, due to the presence of PCL units within the same region. The behaviour of the copolymer networks swollen with different content of water has been investigated to analyze the interaction between water molecules and hydrophobic/hydrophilic domains and provide further insights into the molecular structure of the system.