Poly(lactic acid-co-oxacyclohexadecenlactone) (PLH): A Bio-Based Substrate for Flexible Printed Electronic Devices

The increasing demand for sustainable materials in flexible printed electronics has driven interest in biobased substrates as alternatives to petroleum-derived polymers such as polyethylene terephthalate (PET). This study evaluates a poly(lactic acid-co-oxacyclohexadecenlactone) (PLH) polymer as a biobased substrate for flexible electronics. Mechanically, PLH exhibited a lower Young's modulus (26 ± 3 MPa) than PET (110 ± 10 MPa), indicating greater flexibility, and demonstrates excellent elastic recovery, with no permanent deformation observed after a 0.5 mm extension (2 cm × 0.8 cm samples). Dielectric strength tests confirmed both substrates withstand voltages exceeding 5 kV, with no variation after curing at 60 °C. Thermogravimetric analysis (TGA) of the PLH reveals a temperature at 5% mass loss (T₅%) of approximately 273 °C, indicating the onset of thermal degradation. The corresponding DTG curve shows a main degradation peak at around 295 °C, associated with the primary decomposition process, confirming sufficient thermal stability for printing processes using organic and aqueous inks. Contact angle measurements indicate moderate wettability (PLH: 80° ± 4; PET: 75° ± 5), while confocal microscopy reveals a slightly rougher topside for PLH compared to the smoother PET surface. Nevertheless, PLH supports reliable screen printing of conductive tracks (0.6 cm × 100 μm) with adhesion meeting ASTM D3359 standards. The functional performance of PLH, combined with its biobased origin and validated environmental assessment, highlights its potential as a substrate for flexible electronics with moderate thermal requirements. Future work should address bending durability and surface homogeneity to further enhance PLH applicability.