Effect of plasma treatment on the biodegradation of polyester polyurethane films by bacterial co-culture

Polyurethane (PU), a polymer widely used in the production of foams, coatings, binders and elastomers, remains challenging in terms of its recyclability. While mechanical recycling requires extensive upstream sorting, chemical recycling is associated with environmental and health hazards. This study investigates the effect of plasma-induced surface modification of PU for enhanced biodegradation by bacterial co-culture. PU films were subjected to atmospheric plasma treatment at three power levels, after which they were subjected to biodegradation for 14 days using two bacterial co-cultures: Streptomyces violaceoruber in combination with Rhodococcus ruber (co-culture 1: StrepRhod) and Streptomyces violaceoruber in combination with Bacillus subtilis (co-culture 2: StrepBac). Surface and structural changes were characterized by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), contact angle measurement, and differential scanning calorimetry (DSC). After biodegradation, plasma-treated samples showed greater bacterial colonization, with visible cracks, and pits compared to untreated samples. FTIR analysis revealed changes in absorption peaks associated with carbonyl groups. Surface wettability increased significantly as the contact angle significantly decreased in case of plasma-treated samples biodegraded by co-culture 1 and co-culture 2, respectively. DSC results showed a significant ( P ≤ 0.05) reduction in the glass transition temperature (T g ) for all samples biodegraded by co-culture 1 and 2, compared to the reference PU sample, indicating degradation of amorphous PU regions. The results demonstrated that combining plasma treatment with microbial co-cultures promotes PU biodegradation.