Low Molecular Weight and Polymeric Modifiers as Toughening Agents in Poly(3-Hydroxybutyrate) Films

Abstract

The inherent brittleness of poly(3-hydroxybutyrate) (PHB) prevents its use as a substitute of petroleum-based polymers. Low molecular weight plasticizers, such as tributyl 2-acetyl citrate (TAC), cannot properly solve this issue. Herein, PHB films were obtained using a biosynthesized poly(3-hydroxyoctanoate) (PHO) and a commercially available TAC as toughening agents. The use of TAC strongly decreased the PHB thermal stability up to 200 °C due to the loss of low boiling point plasticizer, while minor weight loss was noticed at this temperature for the PHB-PHO blend. Both agents shifted the glass transition temperature of PHB to a lower temperature, the effect being more pronounced for TAC. The elongation at break of PHB increased by 700% after PHO addition and by only 185% in the case of TAC; this demonstrates an important toughening effect of the polymeric modifier. Migration of TAC to the upper surface of the films and no sign of migration in the case of PHO were highlighted by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) results. In vitro biocompatibility tests showed that all the PHB films are non-toxic towards L929 cells and have no proinflammatory immune response. The use of PHO as a toughening agent in PHB represents an attractive solution to its brittleness in the case of packaging and biomedical applications while conserving its biodegradability and biocompatibility.

Development and Characterization of Fully Renewable and Biodegradable Polyhydroxyalkanoate Blends with Improved Thermoformability

“…Lower crystallinity and enhanced mechanical properties were obtained, which were even better after adding a cross-linking peroxide initiator during processing. More recently, Frone et al [39] also succeeded by using 10% wt. to 20% wt.…”

PHB Processability and Property Improvement with Linear-Chain Polyester Oligomers Used as Plasticizers

“…As an alternative, oligomeric plasticizers have been used. Although they have lower mixing entropy when compared to those with lower molecular weight, they are more thermally stable and, due to low chain mobility, less prone to migration [ 28 ]. Aliphatic polyester oligomers have great potential as PHB plasticizers [ 25 ].…”

Characterization and Biotechnological Potential of Intracellular Polyhydroxybutyrate by Stigeoclonium sp. B23 Using Cassava Peel as Carbon Source

“…No differences in toxicity parameters were observed for PHB nanoparticles between the chorion-protected life stages before 48 h of development and hatched embryos until 96 h. Such a protective role of the chorion and toxicity differences is often observed for nanoparticles, e.g., described for SiO 2 nanoparticles [ 56 ]. In contrast to the observed toxicity on zebrafish embryos, PHB is described as a non-toxic biopolymer [ 57 ], and PHB films such as poly(3-hydroxyoctanoate) (PHO) were not toxic on L929 cells and not pro-inflammatory [ 58 ]. However, PHB biopolymers decreased oxidative stress markers in the blue mussel [ 59 ].…”