Cleaving Side Chains Research Articles

Chromatographic Analysis of Structural Elements of Molecular Polyimide Brushes with Polymethacrylate Side Chains

The method of thin-layer chromatography under critical conditions was used for the analysis of the functional and structural inhomogeneities of polymethylmethacrylate and poly-tert-butylmethacrylate side chains cleaved from molecular polyimide brushes. Acetic acid–containing mobile phases are suggested, allowing a gradual transition from adsorption to exclusion chromatographic regime to be observed upon variation of the mobile phase composition for both cleaved side chains and “reference” polymethylmethacrylate and poly-tert-butylmethacrylate linear polymers. The presence of a few kinds of cleaved side chains having one terminal carboxylic group and differing in the nature of the other terminal group is revealed.

Synthesis and Solution Properties of Loose Polymer Brushes Having Polyimide Backbone and Methylmethacrylate Side Chains

AbstractSummary: Graft‐copolymers with polyimide backbone and PMMA side chains are synthesized by ATRP of methylmethacrylate on the polyimide macroinitiator. The obtained copolymers, macroinitiator, and cleaved side chains are investigated by 1H NMR, SEC, static and dynamic light scattering, sedimentation, and viscosimetry in solutions. The synthesized copolymer is relatively loose polymer brushes: the average distance between grafted PMMA chains is ∼11 nm (4 repeat units of the backbone). The hydrodynamic and conformational characteristics of graft‐copolymers change on passage from ethylacetate to chloroform due to difference in the thermodynamic quality of the solvents with respect to the copolymer components. The backbone is characterized more extended conformation than individual polyimide macromolecule.

Molecular Sugar Sticks: Cylindrical Glycopolymer Brushes

We report the synthesis of glycocylindrical brushes (“molecular sugar sticks”) with poly(3-O-methacryloyl-α,β-d-glucopyranose) (PMAGlc) side chains, using the “grafting from” approach via atom transfer radical polymerization (ATRP) of the protected monomer, 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-d-glucofuranose (MAIGlc). The formation of well-defined brushes with a narrow length distribution was confirmed by gel permeation chromatography with multiangle light scattering detector (GPC-MALS) and 1H NMR. The initiating efficiency of the initiating sites of the polyinitiator poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) were determined to be in the range 0.23 < f < 0.38 by cleaving the side chains from the backbone. The cleaved side chains were analyzed using 1H NMR, GPC/viscosity, and GPC-MALS measurements. Despite the rather low initiating efficiency, the glycocylindrical brushes show the characteristic wormlike structure, as visualized by scanning force microscopy (SFM). The deprotection of the is...

Diffraction analysis of highly ordered smectic supramolecules of conjugated rodlike polymers

A small/wide-angle X-ray scattering and grazing incidence diffraction study of comb-shaped supramolecules of conjugated poly(2,5-pyridinediyl), acid dopant and hydrogen bonded amphiphilic side chains is reported. In solution, polymers are dissolved rodlike particles. When the side-chains are introduced, polymers self-assemble in hierarchic liquid crystals (LC). Diffraction patterns of aligned LC show h00, 020, and 004 reflections, and additional small-angle reflections along the polymer axis. A triangular correlation function indicating a very large correlation length is seen along the smectic axis. An aligned solid structure can be formed by cleaving side chains from the aligned LC.

Anionic graft polymerization of methyl methacrylate on starch and dextrin

AbstractThe anionic graft polymerization of methyl methacrylate on the potassium alkoxide derivative of starch or dextrin in DMSO was studied. The effects of monomer and alkoxide concentrations as well as temperature were investigated. The yield of graft polymer increased with increasing alkoxide concentration. With increasing monomer concentration and with increasing temperature the extent of homopolymer formation increased. The composition of the graft polymers was found to depend on the reaction conditions. Graft polymers having about 10–40% poly(methyl methacrylate) were obtained. There were quantitative differences in yield of isolated graft polymer between starch and dextrin and these were ascribed to differences in the solubility properties of the carbohydrates. Evidence on the structure of the graft polymers and on the mechanism of the graft polymerization was obtained from acid hydrolysis of the graft polymers and determination of the molecular weights of the cleaved side chains.