Straightforward synthesis of complex polymeric architectures with ultra-high chain density.

Synthesis of complex polymeric architectures (CPAs) reversible-deactivation radical polymerization (RDRP) currently relies on the rather inefficient attachment of monofunctional initiation/transfer sites onto CPA precursors. This drawback seriously limits the overall functionality of the resulting (macro)initiators and, consequently, also the total number of installable polymeric chains, which represents a significant bottleneck in the design of new polymeric materials. Here, we show that the (macro)initiator functionality can be substantially amplified by using trichloroacetyl isocyanate as a highly efficient vehicle for the rapid and clean introduction of trichloroacetyl groups (TAGs) into diverse precursors.

Sulfonated polystyrenes: pH and Mg-insensitive amphiphilic copolymers for detergent-free membrane protein isolation.

Amphiphilic polymers are increasingly applied in the detergent-free isolation and functional studies of membrane proteins. However, the carboxylate group present in the structure of many popular variants, such as styrene-maleic acid (SMA) copolymers, brings limitations in terms of polymer sensitivity to precipitation at acidic pH or in the presence of divalent metal cations. Herein, we addressed this problem by replacing carboxylate with the more acidic sulfonate groups.

Tailoring Butyl Methacrylate/Methacrylic Acid Copolymers for the Solubilization of Membrane Proteins: The Influence of Composition and Molecular Weight.

Low-molecular weight (MW) amphiphilic copolymers have been recently introduced as a powerful tool for the detergent-free isolation of cell membrane proteins. Herein, a screening approach is used to identify a new copolymer type for this application. Via a two-step ATRP/acidolysis procedure, a 3 × 3 matrix of well-defined poly[(butyl methacrylate)-co-(methacrylic acid)] copolymers (denoted BMAA) differing in their MW and ratio of hydrophobic (BMA) and hydrophilic (MAA) units is prepared.

Fast and efficient single step liquid chromatography separation of parent homopolymers from block copolymers.

The modified layout of the barrier method called liquid chromatography under limiting conditions of enthalpic interactions is presented. It enables automated quantitative separation of blends of synthetic polymers, for example the single step discrimination of both parent homopolymers from the block copolymers. Moreover, this method enables the estimation of molar mass and molar mass distribution of the block copolymer precursor.

Nano-modified epoxy: the effect of GO-based complex structures on mechanical performance.

The application of nanofillers (NFs) in multicomponent polymer systems is accompanied by important structure-directing effects that are more marked in partially miscible systems, such as polymer-modified epoxy. This study deals with rubber-modified epoxy using different combinations of GO and amine-terminated butadiene-acrylonitrile copolymer (ATBN), including and pre-made grafting. Moreover, GO grafted planar epoxy groups or solely edge-localized carboxyls was used.

MALDI-ToF mass spectrometry detection of intramolecular composition gradient in copolymers.

Since their addition to the polymer-architecture portfolio, gradient copolymers have attracted significant attention. Up to now, however, the existence of the intramolecular composition gradient must have been ascertained by sampling during living copolymerization because a reliable method for the detection of the composition gradient in the finalized copolymer had not been established yet. Here we show that MALDI-ToF mass spectrometry not only identifies imperfect, i.

Local pH and Effective p of a Polyelectrolyte Chain: Two Names for One Quantity?

In recent experiments, the "local pH" near polyelectrolyte chains was determined from the shift in the effective acidity constant of fluorescent pH indicators attached to the macromolecules. This indirect determination raises the question if the analyzed quantity was indeed the "local pH" and what this term actually means. In this study, we combined experiments and simulations to demonstrate that the shift in ionization constant is slightly lower than the difference between the pH and the "local pH".

Formation of core/corona nanoparticles with interpolyelectrolyte complex cores in aqueous solution: insight into chain dynamics in the complex from fluorescence quenching.

Formation of interpolyelectrolyte complexes (IPECs) of poly(methacrylic acid) (PMAA) bearing a fluorescent label (umbelliferone) at the chain end and poly[3,5-bis(trimethyl ammoniummethyl)-4-hydroxystyrene iodide]-block-poly(ethylene oxide) (QNPHOS-PEO) acting as a fluorescence quencher, was followed using a combination of scattering, calorimetry, microscopy and fluorescence spectroscopy techniques. While scattering and microscopy measurements indicated formation of spherical core/corona nanoparticles with the core of the QNPHOS/PMAA complex and the PEO corona, fluorescence measurements showed that both static and dynamic quenching efficiency were increased in the nanoparticle stability region. As the dynamic quenching rate constant remained unchanged, the quenching enhancement was caused by the increase in the local concentration of QNPHOS segments in the microenvironment of the label.

Decomposition of size-exclusion chromatography elution curves of complex branched polymers.

A new method for the decomposition of non-baseline-resolved multimodal elution curves of SEC with the concentration, light scattering and viscosity detection is presented. The method makes possible the characterization of the polymer-sample components, represented by the peaks forming multimodal elution curves, individually and reduces also the error in the calculation of molecular-weight averages. The procedure is demonstrated on narrow molecular-weight distribution polystyrene standards and their mixture as well as on a grafted polymer sample.

Self-assembly of poly(4-methylstyrene)-g-poly(methacrylic acid) graft copolymer in selective solvents for grafts: scattering and molecular dynamics simulation study.

Poly(4-methylstyrene)-g-poly(methacrylic acid) (P4MS-g-PMAA) graft copolymer was synthesized by the grafting-onto method from poly(4-methylstyrene), selectively brominated on methyl groups, and "living" poly(tert-butyl methacrylate). The average degree of polymerization of the backbone and the grafts and the average number of grafts per backbone were 251, 21, and 25, respectively. The self-assembly of P4MS-g-PMAA was studied in methanol and aqueous buffers (selective solvents for grafts).