Accelerating the environmental biodegradation of poly-3-hydroxybutyrate (PHB) via plasma surface treatment

The surface of poly-3-hydroxybutyrate (PHB) was modified using a low-pressure plasma system with air as the process gas to accelerate its biodegradation rate in soil. The water contact angle of PHB was reduced from 98 degrees to 57 degrees after plasma treatment, rendering the surface hydrophilic and also induced an increase in the surface free energy. Etching on the surface was observed after the plasma treatment without a significant change in the surface crystallinity. AFM imaging showed that the plasma treatment increased the surface roughness by about 10 folds and created diverse surface structures. The soil burial test showed an approximately 1.5-fold increase in the biodegradation rate for the plasma-treated sample. Initial microbial attachment and biofilm formation were higher on the modified surface. This study demonstrated that the surface morphology created by plasma treatment promoted initial colonization and subsequent biofilm formation on the PHB surface, facilitating and accelerating its biodegradation in soil.