THE STERIC EFFECT OF SOLVENT MOLECULES IN THE DISSOLUTION OF POLYACRYLONITRILE FROM 5 DIFFERENT N,N-DIMETHYLFORMAMIDE DERIVATIVES AS STUDIED USING RAMAN-SPECTROSCOPY

The steric effect of solvent molecules in the dissolution of polyacryl onitrile (PAN) from five different kinds of N,N-dimethylformamide (DMF ) derivatives was studied using Raman spectroscopy and a laboratory co nstructed laser optical instrument. The dissolution behavior of PAN fr om solvents such as DMF, N,N-dimethylacetamide, N,N-diethylformamide, N,N-dimethylcarbamylchloride, and N,N-dimethyltrichloroacetamide was s tudied with the laser optical method. Raman spectra of the solvents an d solutions provided significant information on the intermolecular int eraction between nitrile and the solvents (i.e., dipole-dipole interac tion). The carbonyl band in each solvent shifted from a lower to a hig her frequency when nitriles were added, and the extent of the shift wa s directly related to the structure and geometry of a subtituent in ea ch solvent molecule. An inverse linear relationship between the value of the dissolution temperature (T-sol) and the extent of the Raman car bonyl shift is demonstrated. It seems reasonable to explain this in te rms of the steric effect of solvent molecules in the dissolution of PA N.