Size exclusion behavior of polymers in amide solvents

Summary

Size exclusion chromatography (SEC) procedure for the determination of molecular weight and molecular weight distribution of acrylonitrile polymers (PAN) is described. The Mark-Houwink-Sakurada parameters of PAN polymers in DMF and 0.01M LiBr-DMF at 60°C were estimated. The values of a parameters obtained by us for PAN prepared both by persulfate-metabisulfite aqueous system (PAN), and azo-bis-isobutyronitrile in DMF solution (PAN-A) were the same, while for PAN sample containing small amounts of sulfonated pendant groups (PAN-S) was higher. The addition of inorganic salt, such as LiBr, to DMF suppressed the abnormal SEC elution behavior observed in the solvent without the electrolyte although SEC of PAN-A showed almost the same results as in DMF with electrolyte. The universal calibration using monodisperse poly(ethylene oxide) standards as well as application of the Mark-Houwink-Sakurada parameters were satisfactory for the determination of the molecular weights.