Preparation of blends of oligo([R,S]-3-hydroxybutyrate) and poly([R]-3-hydroxybutyrate): Thermal properties and molecular dynamic studies

Solvent-cast films of blends of synthetic oligo(R,S]-3-hydroxybutyrate) (OHB) and bacterial PHB were prepared in distinct compositions. The oligomeric amorphous OHB was prepared via ROP of β−butyrolactone in solution employing a new initiator based on Mg(II)/Ti(IV) complex. The FTIR spectroscopy was used to observe the behavior of the vibration modes sensitive to crystallinity with increasing amorphous component content in the polymer blends. Considering the changes in the vibrational spectra, the degree of crystallinity of bacterial PHB was successfully decreased with the addition of OHB. The level of homogeneity of the polymer mixtures was also assessed by DSC and relaxometry. An exponential response was observed between the blend composition and the T₁H values detected by LF-NMR, and similar behavior was observed for the correlation between the experimental T_g values and the relaxation times.