Water and vapor permeability at different temperatures of poly (3-Hydroxybutyrate) dense membranes

Abstract

Polyhydroxyalkanoates (PHAs) are polymers produced from renewable resources with biodegradability and biocompatibility, being therefore attractive for medical and pharmaceutical purposes. Poly (3-hydroxybutyrate) (PHB) is the most important polymer of this family by considering the biotechnology process of its synthesis. In the present study, dense films of PHB were prepared by casting from chloroform solutions (1% m/m). Permeability studies with water, methanol, ethanol and n-propanol were performed using the gravimetric method at different temperatures (from 50 °C to 65 °C). Results provide new data on permeability coefficients of PHB membranes.

Structural impact of hydroxyvalerate in polyhydroxyalkanoates (PHAscl) dense film monitored by XPS and photothermal methods

“…The degree of crystallinity was obtained using Gauss curves to fit the diffractogram peaks and a broad Gauss curve representing the amorphous phase (background). 7 The areas ratio of the total diffractogram peaks to the broad Gauss curve was taken as the degree of crystallinity. The structural measurements were made for samples aged for eight weeks at room temperature.…”

Síntese e caracterização do copolímero poli(3-hidroxibutirato-co-ε-caprolactona) a partir de poli (3-hidroxibutirato) e poli(ε-caprolactona)

“…Dentro da família dos PHAs destaca-se o poli(3-hidroxibutirato), PHB, que apresenta propriedades similares às do polipropileno [2] , sendo, porém, mais duro e quebradiço [3] . Tem crescido significativamente o interesse no estudo do PHB pelo seu variado potencial de aplicação, como em membranas [4] e na preparação de copolímeros, usando o hidroxivalerato, ou de compósitos com hidroxiapatita como forma de torná-lo menos quebradiço, no sentido de aumentar sua empregabilidade.O PHB é um poliéster termoplástico de origem microbiana sintetizado por diversas bactérias (por exemplo, Alcaligenes eutrophus e Rhodospirillum rubrum) que ocorrem naturalmente no solo. Esse é, em muitos casos, o polímero que mais se aproxima de um eco-material ideal: é obtido de fontes renováveis, é facilmente biodegradado em solos de compostagem, é biorreabsorvível e biocompatível (pode ser usado em implantes médicos ou como substrato para crescimento celular) [5,6] .…”

A novel method for the determination of diffusion coefficients in amorphous poly(3-hydroxybutyrate)

“…If we consider this application, the kinetics of drug release must be determined, but quantitative description requires the knowledge of the diffusion coefficient. This characteristic might be measured and/or calculated by a number of approaches already published in the literature [24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

“…Monitoring in the acceptor cell can be done by the measurement of pressure, in the case of gases, or by the determination of the concentration of the diffusing molecule by spectroscopic methods for other substances [32]. The vast majority of publications assumes an exact linear correlation between the permeation and the diffusion coefficients [32][33][34], and the latter is obtained by the division of the measured permeation parameter by a linear factor (S), the physical meaning of which is defined rather diversely. The simple correlation between the two coefficients is the following [32][33][34] …”

“…However, the Flory-Huggins lattice model has a number of weaknesses and the calculation of the interaction parameter from solubility parameters is a further simplification. Because of these difficulties in the calculation of the diffusion coefficient, Poley [34] omitted this step and published only the permeation coefficients themselves.…”