Rapid Estimation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Composition Using ATR-FTIR

Area of Science:

• Polymer Science
• Analytical Chemistry
• Biotechnology

Background:

• Polyhydroxyalkanoates (PHAs) are a promising family of biodegradable polyesters with potential to replace oil-based plastics.
• Their sustainable production by microorganisms and inherent biodegradability are key advantages.
• Tunable thermal and mechanical properties through monomer composition control are crucial for diverse applications.

Purpose of the Study:

• To develop a rapid and facile method for determining the chemical structure of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HBV).
• To establish an alternative to the standard gas-chromatographic method using widely available instrumentation.
• To enable accurate composition analysis of P3HBV copolymers for material characterization.

Main Methods:

• Utilized attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) for composition determination.
• Developed a calibration method based on the linear dependence of normalized absorption band intensity on molar fraction.
• Implemented rapid quenching from melt onto the ATR element to mitigate crystallinity variability and improve reproducibility.

Main Results:

• A calibration method was developed using normalized intensities of two specific absorption bands.
• The method accurately predicts the molar fraction of 3-hydroxybutyrate repeating units (X) in P3HBV samples.
• Prediction intervals of inverse regression were used to evaluate the uncertainty of the composition estimation.

Conclusions:

• The proposed ATR-FTIR method provides a rapid and easy estimation of P3HBV copolymer composition.
• This technique offers a viable alternative to conventional gas chromatography for PHA analysis.
• The method's ability to overcome crystallinity issues enhances its utility in polymer characterization.