Diblock copolymer poly(ethylene oxide)--poly(styrene) (PEO--PS) was adopted to template the synthesis of hierarchically porous Ce-based metal-organic frameworks (MOFs) for the first time. By extending the synergistic effect of Hofmeister ions and soft templates into the water-rich system, UiO-66 type Ce-MOFs with a mesopore size of about 15 nm were achieved. Mesopore size could be further tuned up to approximately 23 nm upon introducing 1,3,5-trimethylbenzene to the micelle core of PEO--PS.
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http://dx.doi.org/10.1039/d2cc01914k | DOI Listing |
Soft Matter
May 2018
Department of Chemistry, College of Staten Island, The City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314, USA.
The glassiness of polymer melts is generally considered to be suppressed by small dimensions, added solvent, and heat. Here, we suggest that glassiness persists at the nanoscale in worm-like micelles composed of amphiphilic diblock copolymers of poly(ethylene oxide)-polystyrene (PS). The glassiness of these worms is indicated by a lack of fluorescence recovery after photobleaching as well as micron-length rigid segments separated by hinges.
View Article and Find Full Text PDFACS Appl Mater Interfaces
June 2015
†Department of Chemical Engineering, University of Patras, 26504 Patras, Greece.
We report the rheological and structural properties of a suspension comprising poly(ethylene oxide)-polystyrene-poly(ethylene oxide) core-shell micellar nanoparticles dispersed in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid. A liquid to soft solid transition was observed at a copolymer concentration of 10 wt % above which an elastic soft material was formed, which was composed of non-ordered jammed core-shell micellar nanoparticles. In the soft solid state, a significant reduction in the size of the nanoparticles, approaching hard sphere behavior, was observed by small-angle X-ray scattering which is attributed to compression of the soft poly(ethylene oxide) coronas.
View Article and Find Full Text PDFJ Nanosci Nanotechnol
October 2013
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China.
Several well defined block copolymers PEO-b-PS and PS-b-PEO-b-PS were synthesized by atom transfer radical polymerization using PEO-Br and Br-PEO-Br as macroinitiators. These copolymers were characterized by GPC and 1H NMR. Mesoporous silicas with large and tunable accessible pores were successfully synthesized by evaporation-induced self-assembly using block copolymers as templates.
View Article and Find Full Text PDFChemistry
June 2012
Aix-Marseille Univ-CNRS, UMR 7273, Institut de Chimie Radicalaire, Equipe Spectrométries Appliquées à la Chimie Structurale, 13397 Marseille, France.
A sample pretreatment was evaluated to enable the production of intact cationic species of synthetic polymers holding a labile end-group using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. More specifically, polymers obtained by nitroxide-mediated polymerization involving the MAMA-SG1 alkoxyamine were stirred for a few hours in trifluoroacetic acid (TFA) to induce the substitution of a tert-butyl group on the nitrogen of nitroxide end-group by a hydrogen atom. Nuclear magnetic resonance, electrospray ionization tandem mass spectrometry, and theoretical calculations were combined to scrutinize this sample pretreatment from both mechanistic and energetic points of view.
View Article and Find Full Text PDFAnal Chem
October 2009
Laboratoire Chimie Provence, Spectrométries Appliquées a la Chimie Structurale, Universités Aix-Marseille I, II & III-CNRS, UMR 6264, F-13397 Marseille Cedex 20, France.
Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) is the technique of choice to achieve molecular weight data for synthetic polymers. Because the success of a MALDI-MS analysis critically depends on a proper matrix and cation selection, which in turn relates closely to the polymer chemical nature and size, prior estimation of the polymer size range strongly helps in rationalizing MALDI sample preparation. We recently showed how pulsed gradient spin echo (PGSE) nuclear magnetic resonance could be used as an advantageous alternative to size exclusion chromatography, to rationalize MALDI sample preparation and confidently interpret MALDI mass spectra for homopolymers.
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