Polyester-Based Polyelectrolyte Complexes: Combining Thermo- and Saloplastic Properties

In this work, we describe the synthesis of polyester-based polyelectrolytes and their corresponding polyelectrolyte complexes (PECs). The polyelectrolytes were prepared via melt polycondensation from partially biobased building blocks. Subsequently, these polyelectrolytes were combined to form polyester PECs (P-PECs) or hybrid complexes (H-PECs) by combining polyester- and vinyl-based polyelectrolytes. The complexation behavior and the thermo-mechanical properties of P-PEC and H-PECs were compared with PECs exclusively made from vinyl-based polyelectrolytes (V-PECs). Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) reveal a glass-transition temperature of approximately 50 °C for P-PEC. Additionally, the stability of PECs in 0.6 M NaCl was assessed, demonstrating the dissolution of P-PEC within 30 min. Neither H-PECs nor V-PECs showed dissolution after 31 days and did not exhibit any indication of a temperature-triggered phase transition. Increasing the relative humidity enhances the strain at the break of all complexes. Overall, P-PECs exhibit, in the dry state, a unique combination of saloplastic and thermoplastic properties.