From Waste to Wires: PBAT/Lignin Biocomposites Functionalized by a CO₂ Laser for Transient Electronics

Polybutylene adipate terephthalate (PBAT), a flexible biodegradable polyester, has gained widespread use in packaging applications due to its ability to degrade under controlled conditions, producing non-toxic substances. While this property makes PBAT particularly attractive for the development of transient electronic devices, this potential application remains unexplored. To address this research gap, we developed PBAT-based composites and modified their electrical properties through CO₂ laser functionalization. Although laser treatment of neat PBAT primarily resulted in material ablation, the incorporation of lignin and silica-based fillers enabled the formation of electrically conductive pathways. Among the various fillers tested, dealkaline lignin (DEALK) and glass fibers (GFs) provided the optimal combination of electrical conductivity, mechanical properties, and processability. Characterization techniques (electrical measurements, optical microscopy, SEM, EDX, and TGA) highlighted that by optimizing laser treatment and the filler concentration, it is possible to produce conductive tracks with remarkably low sheet resistance. Hybrid composites containing 10-15 wt% of GF and 20-25 wt% of lignin demonstrated the best electrical performance with values as low as 3.5 Ω/sq, which were further reduced to 1.72 Ω/sq after laser process optimization. These findings establish PBAT composites as promising candidates for sustainable transient electronics.