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103 results on '"nmr characterization"'

101. Synthesis of siloxanes containing acid-sensitive side groups

Author

JJ Jansema, Bac Rousseeuw, R Puyenbroek, Jc Vandegrampel, Ewjm Vanderdrift, and Polymer Chemistry and Bioengineering

Subjects
Polymers and Plastics, Chemistry, Hydrosilylation, Organic Chemistry, poly(siloxanes), hydrosilylation, Chemical modification, Ether, Photoresist, Methacrylate, chemistry.chemical_compound, Acid sensitive, Reagent, Polymer chemistry, Materials Chemistry, Organic chemistry, nmr characterization
Abstract

New siloxanes with acid-sensitive substituents have been synthesized by means of hydrosilylation, starting from methylhydrosiloxanes. Details of the preparation and characterization are reported. p -t-Butoxycarbonyloxystyrene, p -t-butoxystyrene and t-butyl methacrylate turned out to be excellent reagents in these experiments. 1 H, 13 C and 29 Si nuclear magnetic resonance techniques were used for characterization. The ratio between α and β addition appears to be strongly dependent on the substituents at the vinyl group of the organic moieties.

Published
1996

102. Solid-state 13 C, 15 N and 29 Si NMR characterization of block copolymers with CO 2 capture properties.

Author

Shah FU, Akhtar F, Khan MSU, Akhter Z, and Antzutkin ON

Abstract

Natural abundance solid-state multinuclear ( 13 C, 15 N and 29 Si) cross-polarization magic-angle-spinning NMR was used to study structures of three block copolymers based on polyamide and dimethylsiloxane and two polyamides, one of which including ferrocene in its structure. Assignment of most of the resonance lines in 13 C, 15 N and 29 Si cross-polarization magic-angle-spinning NMR spectra were suggested. A comparative analysis of 13 C isotropic chemical shifts of polyamides with and without ferrocene has revealed a systematic shift towards higher δ -values (de-shielding) explained as the incorporation of paramagnetic ferrocene into the polyamide backbone. In addition, the 13 C NMR resonance lines for ferrocene-based polyamide were significantly broadened, because of paramagnetic effects from ferrocene incorporated in the structure of this polyamide polymer. Single resonance lines with chemical shifts ranging from 88.1 to 91.5 ppm were observed for 15 N sites in all of studied polyamide samples. 29 Si chemical shifts were found to be around -22.4 ppm in polydimethylsiloxane samples that falls in the range of chemical shifts for alkylsiloxane compounds. The CO 2 capture performance of polyamide-dimethylsiloxane-based block copolymers was measured as a function of temperature and pressure. The data revealed that these polymeric materials have potential to uptake CO 2 (up to 9.6 cm 3  g -1 ) at ambient pressures and in the temperature interval 30-40 °C. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Published
2016
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