Solubility of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in sustainable and green solvents: Effect of HV content and comparison between experimental results and theoretical prediction

For the first time, a quantitative analysis of the solubility of poly-3hydroxybutyrrate-co-3hydroxyvalerate (PHBV) in green solvents is proposed. The solubility of two commercial co-polymers, with hydroxyvalerate (HV) contents of 8 %mol and 12 %mol, in 1,3-dioxolane, dimethyl carbonate and butyl acetate was experimentally determined using chloroform as the benchmark and water as the control. The results showed a direct correlation between solubility and temperature, with a maximum at the boiling point of the solvent. For PHBV with an HV content of 8 %mol, solubilities of 265 mg mL-1 for 1,3-dioxolane and dimethyl carbonate and 274 mg mL-1 for butyl acetate were measured; for PHBV with an HV content of 12 %mol, solubilities of 225 mg mL-1, 197 mg mL-1 and 137 mg mL-1 for 1,3-dioxolane, dimethyl carbonate and butyl acetate were measured, respectively. Following Hansen's theory, the PHBV solubility sphere was defined to predict the solubility of the co-polymers in solvents qualitatively. The validation of the sphere was performed by the experimental results herein obtained.