Use of high-performance liquid chromatography for the characterization of synthetic copolymers

✍ Scribed by Gottfried Glöckner; Howard G. Barth

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 691 KB
• Volume: 499
• Category: Article
• ISSN: 1873-3778
• DOI: 10.1016/s0021-9673(00)97009-2

✦ Synopsis

The evaluation of copolymer distribution as a function of molecular weight and chemical composition requires two separations, knotin as cross-fractionation. This procedure can be substantially improved by using high-performance liquid chromatographic (HPLC) techniques, including size-exclusion chromatography for the separation by molecular size. The separation by chemical composition can be achieved by gradient HPLC. Examples are given for copolymers of styrene and ethyl methacrylate (SEMA). Gradient HPLC of these and similar copolymers can be performed in both normal-phase and reversed-phase modes with inversion of elution order. In isooctane-tetrahydrofuran (THF) mixtures on polar columns, the elution of SEMA samples occurs at a higher THF concentration than required by solubility, i.e., with a distinct contribution of adsorption to retention. In contrast, reversedphase elution with methanol-THF mixtures takes place almost exactly at the solubility borderline of the system.