Terahertz Time-Domain Spectroscopy of Thermoresponsive Polymers in Aqueous Solution

The behavior of highly concentrated aqueous solutions of two thermoresponsive polymers poly(N-isopropylacrylamide) (PNIPAm) and poly(N-vinylcaprolactam) (PVCL) have been investigated by terahertz time-domain spectroscopy (THz-TDS). Measurements have been performed for concentrations up to 20 wt %, over a frequency range from 0.3 to 1.5 THz and for temperatures from 20 to 45 °C including the zone for lower critical solution temperature (LCST). THz-TDS enables the study of the behavior of water present in the solution (i.e., free or bound to the polymer). From these measurements, in addition to phase transition temperature, thermodynamic data such as variation of enthalpy and entropy can be inferred. Thanks to these data, further insights upon the mechanism involved during the dehydration phenomenon were obtained. These results were compared to the ones issued from dynamic light scattering, spectroscopy, or microscopy techniques to underline the interest to use THz-TDS as a powerful tool to characterize the behavior of thermoresponsive polymers in highly concentrated solutions

Utilisation du groupe ferrocenyle donneur d'electron potentiel dans des systemes multi-constituants construits autour de complexes bis-terpyridine de l'osmium et du ruthenium

Available from INIST (FR), Document Supply Service, under shelf-number : TD 80828 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

An expeditious route to cis-Ru(bpy)2C12 (bpy=2,2′-bipyridine) using carbohydrates as reducers

International audienceThe tandem use of simple mono- or disaccharides and vitamin C as organic reducers allows the synthesis of the widely used starting material cis-Ru(bpy)2Cl2 (where bpy = 2,2′-bipyridine) from commercial ruthenium (III) chloride in less than half an hour. Notably, the reaction can be run in organic aqueous solvent or in only water, hence it can be adapted to substituted 2,2′-bipyridines

Enhanced photo-responsiveness in a photoswitchable system model: emergent hormetic catalysis

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Criblage de structures chimiques (modèles de composants pour l'électronique moléculaire)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Switching a pH indicator by a reversible photoacid: A quantitative analysis of a new two-component photochromic system

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Deformation of a “Rigid” Molecule in Self-Assembled Nanostructures

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TRISPHAT Salts. Efficient NMR Chiral Shift and Resolving Agents for Substituted Cyclometallated Ruthenium Bis(diimine) Complexes

The determination of the enantiomeric purity of monocationic ruthenium(II) cyclometallated complexes is easily carried out by 1H-NMR analysis using a TRISPHAT salt as a diamagnetic chiral shift reagent. Resolution of the organometallic complexes can be conveniently carried by preparative thin layer chromatography using TRISPHAT as a chiral counter-ion