Gel permeation chromatography (GPC) is an established separation method for the determination of molecular weight averages (Mn) and molecular weight distributions (PDI = Mw/Mn) of polymers. The importance of analytical aspect of GPC is well documented in the literature however little effort has been made to extend the use of this important technique for the fractionation of polymer samples on a preparative scale.

GPC separates according to molecular size. The elution order is from big (high molar masses) to small molecules (low molar masses). Therefore, the method can be used for additive analysis, determination of oligomer content and purification of polymer sample. An important extension of Prep GPC in polymer synthesis is in the removal of low molecular weight impurities, e.g., residual initiator, additives. These low molecular weight components are eluted after the main fraction of the polymer and can be readily removed by “end-shaving”.

The highest and lower molecular weight fractions are indicated by the front- and tail-end of the chromatogram. The cut-off position of mass- shaving is mainly dictated by the shape of the GPC curve and will determine the amount of material recovered. The polymer fraction can be recovered by removing the solvent (under vacuum) and the Mn and Mw/Mn of the samples can be determined by the analytical GPC.

Equipment

Pump: Waters 1525 Binary HPLC Pump

Stationary phase: Styragel

Columns: Ultrastyragel 100A, 10-3A and 10-4A THF 19x300 INT’L HAZA

Detection: Waters 2414 Differential Refractometer

Solvent: THF

Flow Rate: up to 6 mL/min

Injection: manual injector with tube coiled, 2 mL

Please contact Krystyna Brzezinska (kbrzez@mrl.ucsb.edu) to schedule training. Before training starts please read MANUAL.