Tuning Poly(3-hydroxybutyrate) (P3HB) Properties by Tailored Segmented Biocopolymers

Poly(3-hydroxybutyrate) (P3HB) is a thermoplastic, biocompatible, and truly biodegradable polyester produced by bacteria and characterized by a high degree of crystallinity due to its isotactic nature. In order to tackle the challenges of its processability at the time of developing new green materials, the use of biodegradable additives is highly recommended. In this work, the biodegradable and biocompatible semicrystalline multiblock copolyester poly(butylene succinate-butylene dilinoleate) (PBS:DLA), shortly abbreviated as CoPo, is used to produce new P3HB blends. The hard:soft segment ratio of the copolymer can be selected as desired during its synthesis. Two different copolymers, namely, CoPo70 (70:30) and CoPo50 (50:50), were blended with P3HB at different concentrations, i.e., 5, 10, and 20 wt %, to investigate the phase behavior of blends. Furthermore, the effect of CoPo segmental composition and its content was evaluated experimentally as well as by dissipative particle dynamics (DPD) simulations. Results suggest the immiscibility of blends at biocopolymer contents higher than 5 wt % for both copolymers with larger phase separated domains using CoPo70. It is found that the processability and the mechanical performance are dependent on the type and amount of biocopolymer added to P3HB, allowing significant improvements with respect to the neat polymer. This work systematically compiles the processability and mechanical properties of different P3HB/PBS:DLA blends as a function of the hard:soft segment ratio of the CoPo. The selection of the most suitable blend will then depend on the processing requirements and specifications of the final green biomaterial and can be based on the results reported in this work.