Separation of Branched Poly(bisphenol A carbonate) Structures by Solvent Gradient at Near-Critical Conditions and Two-Dimensional Liquid Chromatography.

Branching is a molecular metric that strongly influences the application properties of polymers. Consequently, detailed information on the microstructure is required to gain a deeper understanding of structure-property relationships. In the present case, we employ high-performance liquid chromatography to characterize the branching in a poly(bisphenol A carbonate) (PC).

Selective chromatographic separation of polycarbonate according to hydroxyl end-groups using a porous graphitic carbon column.

Porous graphitic carbon (PGC) has shown unique separation efficiency in liquid chromatography for a wide range of substance classes. In the characterization of polymers PGC has particularly been used for analysis of polyolefins. Its retention mechanisms differ dramatically from those of silica-based stationary phases and therefore allow interesting applications.

Size-exclusion chromatography-from high-performance to ultra-performance.

Size-exclusion chromatography (SEC) enables measurement of the average molecular weights and molecular-weight distributions of polymers. Because these characteristics may, in turn, be correlated with important performance characteristics of plastics, SEC is an essential analytical technique for characterization of macromolecules. Although SEC is one of the oldest instrumental chromatographic techniques, it is still under continuous development, as a result of the great demand for increased resolution and faster analysis in SEC.

Comprehensive two-dimensional ultrahigh-pressure liquid chromatography for separations of polymers.

Online comprehensive two-dimensional liquid chromatography (LC × LC) is a technique of great importance, because it offers much higher peak capacities than separations in a single dimension. When analyzing polymer samples, LC × LC can provide detailed information on two mutually dependent polymer distributions. Because both molecular-weight distributions and chemical-composition distributions are typically present in synthetic copolymers, combinations of interactive LC with size-exclusion chromatography (SEC) are especially useful for (co)polymer analyses.

Deformation and degradation of polymers in ultra-high-pressure liquid chromatography.

Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles and narrow bore tubing in combination with high pressures generate significant shear and extensional forces in UHPLC systems, which may affect polymer chains.

Fast and efficient size-based separations of polymers using ultra-high-pressure liquid chromatography.

Ultra-high-pressure liquid chromatography (UHPLC) has great potential for the separations of both small molecules and polymers. However, the implementation of UHPLC for the analysis of macromolecules invokes several problems. First, to provide information on the molecular-weight distribution of a polymer, size-exclusion (SEC) columns with specific pore sizes are needed.