Tailoring the viscoelastic properties of injectable biocomposites: A spectroscopic assessment of the interactions between organic carriers and bioactive glass particles

Injectable bioglass (BG) pastes were produced using a melt-quenched glass based on CaO–MgO–SiO2–Na2O–P2O5–CaF2 and two organic carriers, namely polyethylene glycol (PEG) and glycerol (Gly). The interactions between the organic carriers and the surface of the BG particles were assessed by spectroscopic methods (Fourier Transform Infrared, Raman, as well as 29Si and 13C solid-state NMR spectroscopy) in order to understand their effects on the viscoelastic properties of the biocomposites. While pure physical interactions were detected between PEG and the surface of the BG particles, chemical bonding was observed between glycerol and BG, enhancing the network cross-linking degree. Accordingly, the BG network of Gly-BG pastes was more condensed (higher fraction of Q [3] units detected by Raman spectroscopy) in comparison to that of PEG-BG and bare BG. Such chemical interactions between the organic carrier and BG were shown to negatively affect the viscoelastic behaviour of the resulting pastes. Thus, the PEG-based biocomposite exhibited improved flowability in comparison to its analogous Gly-BG biocomposite