Assisted Microwave polymer synthesis

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The multicomponent Debus–Radziszewski reaction in macromolecular chemistry

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Poly(tetrasubstituted-aryl imidazole)s: A Way to Obtain Multi-Chromophore Materials with a Tunable Absorption/Emission Wavelength

International audienceSome original poly(tetrasubstituted imidazole)s incorporating different units were synthesized and characterized. These materials were obtained via a cascade polycondensation process assisted by microwave irradiation that was developed by our team. This time, we integrated two well-known chromophore structures into the macromolecular backbone, which were benzothiadiazole (BTD) and diketopyrrolopyrrole (DKPP). These new polymers were fully characterized: their chemical structures were confirmed using NMR spectroscopy and their thermal, optical and electrochemical properties were investigated and compared with a reference polymer containing a phenyl spacer instead of the mentioned chromophore units. These materials were found to exhibit a large Stokes shift of up to 350 nm. Furthermore, a polymer presenting large absorption on the UV–visible range and an emission close to the near-infrared region was obtained by coupling the mentioned moieties. According to the established properties of this latter polymer, it presents a potential for applications in biological imaging or optoelectronic devices

Synthesis and study of aromatic and heterocyclic luminescent compounds and polymers.

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Innovative polypropylene based blends by in situ polymerization of a polyimide dispersed phase by reactive extrusion

International audiencePolypropylene/polyimide (PP/PI) blends were synthesized by reactive extrusion with the in situ polymerization of the polyimide phase in presence of maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer. Blends were reactively processed in a twin-screw extruder at 200 • C, with the PI content varying from 10 to 40 wt %. Examination of morphology by scanning electron microscopy (SEM) depicted a fine sub-micrometer dispersion of the polyimide phase ranging from 170 to 250 nm in diameter, for all PI concentrations. The advantage of the in situ approach compared to the more classical dispersion process was clearly demonstrated. The in situ synthesized PI phase was characterized by NMR and FTIR after separation by Soxhlet selective extraction. Differential scanning calorimetry (DSC) analysis of the blends showed no modifications of PP crystallinity with the addition of PI. Rheological behaviors showed a significant impact of the polyimide phase on the storage modulus with the appearance of a secondary storage modulus plateau at low frequencies. Thermogravimetric analyses evidenced an improvement of the thermal stability of the blends, with an increase of the decomposition temperature up to 35°C depending on the polyimide content. Mechanical properties were also improved due to the high mechanical strength of the polyimide phase, with an increase in Young's modulus up to +35 % for the highest polyimide content

Polymerization of monolayers of 3-substituted pyrroles

Derivatives of 3-substituted pyrroles were spread at the air-water interface. Stable films could be obtained for pyrroles with side chains containing more than 10 carbons. 3-Hexadecanoylpyrrole could not be polymerized as a monolayer whereas the alkyl derivatives could be polymerized successfully without having additional monomer in the subphase. The monolayers could be transferred onto hydrophobic substrates with transfer ratios close to unity. The polymers formed were soluble in chloroform and tetrahydrofuran. Molecular-weight averages obtained by gel permeation chromatography ranged from 3500 to 6000 when polymerized on ammonium peroxydisulfate and 5000 to 15000 when polymerized on ferric chloride subphase solutions. 1H NMR indicates that the polymerization is highly regular, leading to a constitutionally ordered 2,5-poly(3-alkylpyrrole)