Functional Polystyrene Derivatives Influence the Miscibility and Helical Peptide Secondary Structures of Poly(γ-benzyl l-glutamate)

Abstract

We synthesized polystyrene (PS) and poly(acetoxystyrene) (PAS) homopolymers through atom transfer radical polymerization (of styrene and 4-acetoxystryene monomers, respectively) and then prepared poly(vinylphenol) (PVPh) through acetoxyl hydrazinolysis of PAS with hydrazine monohydrate. To investigate the influences of these three functionalized polystyrene derivatives on the helical peptide secondary structures and miscibility behavior of polypeptide homopolymers, we blended PS, PAS, and PVPh with a low-molecular-weight poly(γ-benzyl l-glutamate) (PBLG) homopolymer and analyzed these blends using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, solid state nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray diffraction (WAXD). Variations in the intermolecular interactions (e.g., π–π, dipole–dipole, hydrogen bonding) strongly affected the miscibility behavior and secondary structures of PBLG. The weak π–π interactions between PS and PBLG resulted in ...