Polyacrylonitrile Powder Dissolution Behavior in Organic Solvents via Time-Resolved FTIR-ATR Spectroscopy

The dissolution mechanism of polyacrylonitrile (PAN) in solvent (dimethyl sulfoxide (DMSO), N, N-dimethylacetamide (DMAC) or N, N-dimethylformamide (DMF)) was investigated by theoretical and experimental approach. Theoretical simulation revealed DMAc and DMF adopt planar two-dimensional structures with a resonance-stabilized N–C=O group, whereas DMSO exhibits a three-dimensional configuration. The dominant role of the interaction between free-state solvent molecules and PAN chains in the dissolution process was confirmed through analysis of zero-point energy between solvent–solvent and solvent–PAN. The interaction peaks assignment between solvent and PAN were identified by analyzing the Fourier transform infrared spectroscopy (FTIR) characteristic peaks of red or blue shift. By performing peak fitting on time- resolved attenuated total reflection FTIR spectroscopy revealed the mechanism of microscopic dissolution. Viscosity measurements showed an initial increase followed by a decrease and eventual stabilization of viscosity, demonstrating a swelling–dissolution mechanism.