A tuneable switch for controlling environmental degradation of bioplastics: addition of isothiazolinone to polyhydroxyalkanoates

• Published in: PloS one Vol. 8; no. 10; p. e75817
• Main Authors: Woolnough, Catherine Anne, Yee, Lachlan Hartley, Charlton, Timothy Stuart, Foster, Leslie John Ray
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.10.2013; Public Library of Science (PLoS)
• Subjects: Antifouling; Antifouling substances; Biodegradability; Biodegradable materials; Biodegradation; Biodegradation, Environmental; Biofilms - drug effects; Biofilms - growth & development; Biofouling; Bioplastics; Calorimetry, Differential Scanning; Chromatography; Colonization; Environmental degradation; Hydroxybutyrates - metabolism; Isothiazolinone; Kinetics; Mechanical properties; Melt temperature; Microorganisms; Microscopy, Confocal; Molecular Weight; Offset printing; Plastics - metabolism; Polyesters - metabolism; Polyhydroxyalkanoates; Polyhydroxybutyrate; Polyhydroxybutyric acid; Polyhydroxyvalerate; Polymers; Protective coatings; Soil - chemistry; Soil microbiology; Soil Pollutants - metabolism; Soil temperature; Temperature; Tensile Strength; Thiazoles - chemistry; Thiazoles - pharmacology; Weight loss; Weight reduction; Australia; United States > US; New South Wales Australia
• DOI: 10.1371/journal.pone.0075817
• ISSN: 1932-6203

Controlling the environmental degradation of polyhydroxybutyrate (PHB) and polyhydroxyvalerate (P(HB-co-HV)) bioplastics would expand the range of their potential applications. Combining PHB and P(HB-co-HV) films with the anti-fouling agent 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOI, <10% w/w) restricted microbial colonisation in soil, but did not significantly affect melting temperature or the tensile strength of films. DCOI films showed reduced biofouling and postponed the onset of weight loss by up to 100 days, a 10-fold increase compared to unmodified films where the microbial coverage was significant. In addition, the rate of PHA-DCOI weight loss, post-onset, reduced by about 150%; in contrast a recorded weight loss of only 0.05% per day for P(HB-co-HV) with a 10% DCOI loading was observed. This is in stark contrast to the unmodified PHB film, where a recorded weight loss of only 0.75% per day was made. The 'switch' that initiates film weight loss, and its subsequent reduced rate, depended on the DCOI loading to control biofouling. The control of biofouling and environmental degradation for these DCOI modified bioplastics increases their potential use in biodegradable applications.