Solubility of polyhydroxyalkanoates by experiment and thermodynamic correlations

Abstract

This article presents and develops the thermodynamic correlation model to obtain the solubility of polyhydroxyalkanoates (PHAs) in solvents. This model offers a new way to evaluate the polymer solubility parameters and regressions between experimental solubility and solubility parameters. Important parameters influencing solubility such as temperature, polymer molecular weight, crystallinity, and the kind of PHAs were studied. Experiments were carried out on PHB-co-Hx copolymers of different contents. Finally, a model which takes into account these parameters were established and tested on 232 experimental points. The method developed could be used for the selection of a solvent with high efficiency, low price, and low toxicity.

Efficient P(3HB) extraction from Burkholderia sacchari cells using non-chlorinated solvents

“…The model applied in this work to predict the P(3HB) solubility in the various solvents was published by Jacquel et al (2007). These authors adapted to the homopolymer P(3HB) the equations based on Hansen's solubility parameters which are widely used in plastic and pigment technology.…”

“…The ranges of temperature and chain length suggest the limitations of this method: if these boundaries are crossed, the reliability of the prediction strongly decreases. It should also be noted that the experimental points used to propose the solubility equation were obtained in the low solubility area [25]. Thus, for the current purpose, the solubility values generated by equation (1) were used only as mere indicators to enable a first evaluation of the solvents previously selected using the GSK Solvent selection Guide.…”

“…The numerical parameters of the equation were calibrated by 175 experimental points of measured solubility, obtained with polymer-solvent systems at temperatures ranging from 30°C to 70°C and Mw from 4500 Da to 1300000 Da, using 20 different solvents [25]. The ranges of temperature and chain length suggest the limitations of this method: if these boundaries are crossed, the reliability of the prediction strongly decreases.…”

“…The Hansen parameters for P(3HB) were calculated for the first time using a fully predictive group contribution method [24]. Jacquel et al (2007), however, conferred more reliability to the model by calculating them from experimental data. For the purpose, they used a P(3HB) homopolymer …”

“…The first one is based on the GSK Solvent Selection Guide [21][22][23] that helps in the adoption of an objective definition of 'green solvent'. The second one is the set of predictive equations developed for the solubility of P(3HB) in different organic solvents [24][25]. These equations allowed the screening of a large number of industrial solvents, leaving experimental analysis only to confirm the performances of few best solvents.…”