THERMAL FIELD-FLOW FRACTIONATION OF POLYTETRAHYDROFURAN

The possibility to fractionate polytetrahydrofuran (PTHF) samples effectively with Thermal Field Flow Fractionation has been investigated. Retention measurements of four standards of different molecular mass were performed in eight organic solvents. When methylethylketone or dioxane were used no retention was found. Highest retention for a given molecular mass was obtained with the solvents toluene and ethylbenzene. However, in ethyl acetate the highest separation speed was observed. Plate height measurements showed that both the thermal and molecular diffusion coefficients of the PTHF standards are very high in ethyl acetate. According to theory, this combination should result in a high separation speed. A baseline separation of two PTHF standards with molecular masses of 67 000 and 282 300 could be obtained in 8 minutes when ethyl acetate was used as the solvent.