Search results for "NITROXIDE"
showing 7 items of 47 documents
The antioxidant behavior of functional nitroxide grafted polyethylene samples
2015
In this work, the thermo- and photo-oxidation stability of functional nitroxide grafted polyethylene (PE) samples was tested.
Contribution of Protein Flexibility to the Foaming Properties of Casein
1990
The effect of biopolymer flexibility on the foaming properties of casein was investigated. Flexibility was altered by: (1) chemical modification (covalent binding of a monosaccharide on the lysyl residues) or (2) pH change. Electron Spin Resonance was used to measure the reorientational frequency of casein residues labeled with nitroxide radicals. High levels of glycosylation induced increased protein flexibility and improved the foaming capacity. Good agreement was observed between higher values of flexibility and improved surface properties near the isoelectric point.
Grafting of polymer chains on the surface of carbon nanotubes via nitroxide radical coupling reaction
2015
Poly(butylene succinate) (PBS) was grafted on the surface of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) modified multi-walled carbon nanotubes (MWCNTs) via a nitroxide radical coupling reaction. TEMPO functionalized MWCNTs (MWCNTs-g-TEMPO) were synthesized using the Cu(I)-catalyzed azide/alkyne click chemistry approach and the covalent bond of the nitroxide moieties onto the MWCNTs was confirmed via electron paramagnetic resonance (EPR) spectroscopy. The PBS grafting on the sidewalls of MWCNTs was carried out in solution via peroxide-induced formation of macroradicals and it was confirmed by EPR and attenuated total reflectance Fourier transform infrared analysis. Preliminary rheological …
A new approach for the synthesis of magnetic materials based on nitroxide free radicals and inorganic coordination polymers
2001
The use of nitronyl nitroxide (NN) radicals as spectators inside extended inorganic magnetic lattices is described. Two possibilities are presently being explored, namely, the design of oxalato-bridged bimetallic networks by using cationic NN radicals of the N-alkylpyridinium type as templating agents, and the design of bimetallic lattices based on hexacyanometalates and nickel(II) diaminocomplexes incorporating anionic NN radicals of the carboxyphenyl type.
Functionalization of aliphatic polyesters by nitroxide radical coupling
2014
Functionalized poly(butylene succinate) (PBS) samples were prepared by a post-polymerization method based on the coupling reaction between TEMPO derivatives bearing different functionalities and PBS macroradicals generated by H-abstraction using a peroxide. 4-Benzoyloxy-2,2,6,6-tetramethylpiperidine-1- oxyl (BzO-TEMPO) and 4-(1-naphthoate)-2,2,6,6-tetramethylpiperidine-1-oxyl (NfO-TEMPO), a pro-fluorescent nitroxide, were successfully grafted on PBS, as revealed by MALDI TOF MS and UV-Vis spectroscopy. The functionalization degrees were accurately determined by UV-Vis analysis and confirmed by 1H-NMR spectroscopy. The grafting site was identified by combining theoretical calculations with e…
Functionalized poly(butylene succinate) by nitroxide radical coupling
2014
In recent years there has been a growing interest in developing sustainable alternatives to oil-based plastics. In particular, biodegradable aliphatic polyesters, such as poly(lactic acid) (PLA) and poly(butylene succinate) (PBS), are becoming increasingly important due to their valuable properties including thermoplastic processability and thermo-mechanical properties. Nonetheless, these materials present several drawbacks, such as the lack of reactive functionalities that are limiting their applications, versatility and successful use as commodity plastics. In this work it was investigated for the first time a new method of preparation of functionalized PBS by a post-polymerization approa…
Grafting of polymer chains on the surface of carbon nanotubes via nitroxide radical coupling reaction
2016
Poly(butylene succinate)/MWCNTs nanocomposites with improved dispersion and with nanotubes embedded/immobilized into the polymer matrix were here prepared by an alternative "grafting to" method based on thenitroxide radical coupling reaction. Poly(butylene succinate) (PBS) was grafted on the surface of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) modified multi-walled carbon nanotubes (MWCNTs) via a nitroxide radical coupling reaction. TEMPO functionalized MWCNTs (MWCNTs-g-TEMPO) were synthesized using the Cu(I)-catalyzed azide/alkyne click chemistry approach and the covalent bond of the nitroxide moieties onto the MWCNTs was confirmed via electron paramagnetic resonance (EPR) spectroscopy.…