Insights into the miscibility characteristics of plastic-mimetic polypeptide with hydroxypropylmethylcellulose: Investigation of thermal degradability and intermolecular interactions

•A novel plastic-derived poly[0.8(AVGVP),0.2(AEGVP)] was synthesized and characterized with Tt, 1H NMR, and 13C NMR.•Miscibility characteristics of the polypeptide with HPMC explored both in the solution and solid phase.•FTIR guaranteed the intermolecular hydrogen bonding between the polypentapeptide and HPMC.•DSC scrutiny demonstrated the single Tg values for all the blend ratios, and SEM and XRD analysis substantiated the results.•TGA has shown the enhanced thermal stability of the blends as compared to individual polymers. In this investigation, we integrated the parent recurring sequence of the plastic-derived polypeptide, poly[0.8(AVGVP),0.2(AEGVP)] (A, V, G, P, and E represents Alanine, Valine, Glycine, Proline, and Glutamic acid respectively) followed by characterization with inverse transition temperature, 13C, and 1H-NMR spectroscopy. The miscibility attributes of poly[0.8(AVGVP),0.2(AEGVP)] with Hydroxypropylmethylcellulose was examined both in aqueous and solid-phase. The Huggins’ co-efficient [KH], the intrinsic viscosity [η], the interaction parameters ΔB and μ suggested by Chee, ΔK and β recommended by Jiang and Han, α by Sun, Δ[η]m by Garcia showed that the polypeptide was miscible with HPMC in all proportions. DSC studies revealed single Tg values, and TGA manifested the enhanced thermal stability for all the proportions compared with their individuals. Further, verified the results by SEM and XRD. The FTIR evidenced existence of intermolecular hydrogen bonding between the two constituent polymers that caused the miscible blend system.