GEL-PERMEATION CHROMATOGRAPH INTERFACE TO COLLECT SOLVENT-FREE POLYMER FRACTIONS FOR COMPOSITION DRIFT ANALYSIS

An interface is described that is capable of stripping solvent from polymer solutions emerging from an interfaced high‐temperature gel permeation chromatograph. The chemical composition of each solvent‐free polymer fraction is then determined using Fourier transform infrared (FTIR) or other techniques to obtain the composition drift (CD) pattern of the polymer (i.e., variation of chemical composition as a function of molecular weight). The interface consists of a vacuum oven into which an ultrasonic nebulizer and a stepper motor have been incorporated. The stepper motor drives a fraction collector, equipped with a set of KBr plates, onto which the nebulized polymer solution is sprayed. The temperature and pressure of the interface are maintained so as to strip the solvent from the chromatographic effluent as it impinges on the collector substrates. The technique, which had been applied to the % ethylene CD of ethylene‐propylene rubbers, is employed in the analysis of a block copolymer reaction product. In the example given, the CD pattern of the reaction product generated is simulated along with the observed molecular weight distribution pattern to arrive at the approximate composition of the reaction product. For many applications, this approach eliminates the need to carry out tedious solvent/nonsolvent fractionations commonly employed in the characterization of the compositional heterogeneities in block copolymer reaction products. Copyright © 1990 John Wiley & Sons, Inc.