Principles and potential of solvent gradient size-exclusion chromatography for polymer analysis.

The properties of a polymeric material are influenced by its underlying molecular distributions, including the molecular-weight (MWD), chemical-composition (CCD), and/or block-length (BLD) distributions. Gradient-elution liquid chromatography (LC) is commonly used to determine the CCD. Due to the limited solubility of polymers, samples are often dissolved in strong solvents.

Thermal modulation to enhance two-dimensional liquid chromatography separations of polymers.

Many materials used in a wide range of fields consist of polymers that feature great structural complexity. One particularly suitable technique for characterising these complex polymers, that often feature correlated distributions in e.g.

Iterative RAFT-Mediated Copolymerization of Styrene and Maleic Anhydride toward Sequence- and Length-Controlled Copolymers and Their Applications for Solubilizing Lipid Membranes.

The use of poly(styrene--maleic acid) (SMA) for the solubilization of lipid membranes and membrane proteins is becoming more widespread, and with this, the need increases to better understand the chemical properties of the copolymer and how these translate into membrane solubilization properties. SMA comes in many different flavors that include the ratio of styrene to maleic acid, comonomer sequence distribution, average chain length, dispersity, and potential chemical modifications. In this work, the synthesis and membrane active properties are described for 2:1 (periodic) SMA copolymers with varying from ∼1.

Simultaneous characterization of poly(acrylic acid) and polysaccharide polymers and copolymers.

Copolymer products that result from grafting acrylic acid and other hydrophilic monomers onto polysaccharides have recently gained significant interest in research and industry. Originating from renewable sources, these biodegradable, low toxicity, and polar copolymer products exhibit potential to replace polymers from fossil sources in several applications and industries. The methods usually employed to characterize these copolymers are, however, quite limited, especially for the measurement of bulk properties.

Two-Dimensional Liquid Chromatography Analysis of Polystyrene/Polybutadiene Block Copolymers.

A detailed characterization of a commercial polystyrene/polybutadiene block copolymer material (Styrolux) was carried out using two-dimensional liquid chromatography (2D-LC). The Styrolux is prepared by statistical linking reaction of two different polystyrene- block-polybutadienyl anion precursors with a multivalent linking agent. Therefore, it is a mixture of a number of branched block copolymers different in molecular weight, composition, and chain architecture.

Strip-based regression: a method to obtain comprehensive co-polymer architectures from matrix-assisted laser desorption ionisation-mass spectrometry data.

A method aimed to obtain the relative abundances of all molecular species in highly overlapped mass spectra is presented. Its performance is demonstrated with an example of matrix-assisted laser desorption ionization (MALDI) spectra obtained from a polysterene-co-polyisoprene sample, retrieving the full co-polymer architecture. The method is based on a multiple regression operation, applied locally at consecutive regions.

Topology characterization by MALDI-ToF-MS of enzymatically synthesized poly(lactide-co-glycolide).

Lipase catalyzed copolymerization of the monomers lactide and glycolide by Pseudomonas cepacia employing a molar ratio of 80L/20G has been studied. The copolymers were characterized by MALDI-ToF-MS, DSC, SEC and NMR. MALDI-ToF-MS has successfully been used not only to determine end groups and chemical composition but even the microstructure of the copolymers.

Synthesis of polypeptide based rod-coil block copolymers.

A bifunctional initiator was synthesized and used for a sequence of a nickel initiated polymerization of gamma-benzyl-L-glutamate-N-carboxy anhydride and atom transfer radical polymerization of methyl methacrylate yielding a rod-coil block copolymer.

New diphosphine ligands based on diphenyl ether for the Pd-catalyzed CO/ethene copolymerization.

The catalytic activity and selectivity of palladium(II) complexes of new, flexible bidentate ligands in the CO/ethene copolymerization reaction have been found to change considerably with the steric properties of the ligands.

Molar mass distributions by gradient liquid chromatography: predicting and tailoring selectivity.

Interactive liquid chromatography (iLC) for polymer analysis is usually applied to the characterisation of distributions other than molar mass. In particular, its use for the determination of chemical-composition, functionality-type and tacticity distributions has been demonstrated. The application of iLC for the determination of molar mass distributions (MMDs), however, has not yet been fully explored.

Olefin copolymerization via reversible addition-fragmentation chain transfer.

Successful statistical copolymerization of an alpha-olefin (1-octene) with an acrylate (butyl acrylate, BA) and with a methacrylate (methyl methacrylate, MMA), employing reversible addition-fragmentation chain transfer (RAFT) mediated polymerization has been accomplished