The application of synthetic flavinium
organocatalysts for the
in situ regeneration of oxidized cofactors NAD(P)+ using
O2 as the terminal oxidant without any special illumination
or equipment is reported. With the aid of the highly active bridged
flavinium catalyst, the rate of NAD(P)H oxidation is accelerated by
3 orders of magnitude. The results show that the catalytic activity
of the bridged flavinium catalyst is not dependent on light but on
only oxygen. Furthermore, this catalyst is compatible with various
preparative enzymatic oxidation reactions. A hydride transfer mechanism
is proposed for the presented system.
This work designed a lignin-based reinforcing agent for reinforcing natural rubber (NR) via building up an integrated interfacial network. A facile lignin modification approach was developed using a cyclic anhydride with a long alkene chain, (2dodecen-1-yl)succinic anhydride. The grafting of the modifiers preferentially takes place at the aliphatic −OH sites as indicated by 2D heteronuclear single-quantum coherence and 31 P NMR spectra. The amount of grafted modifier was estimated via TGA, being 27.1 and 48.8 wt % for the two modified lignin samples. The high degree of modification results in an elevated molecular weight, reduced T g , and improved hydrophobicity. The NR composites show comparable mechanical properties when 30 wt % of carbon black was replaced with modified lignin. The modification of lignin generates more −COOH groups, which facilitates coordination interactions, and the introduction of zinc dimethacrylate imparts further improved mechanical properties beyond the counterpart with carbon black, especially for the stress at low deformation. Stress relaxation and cyclic tensile tests reveal that these composites are able to largely keep and recover the network structure due to the coordination interaction. This work provides a versatile lignin-based reinforcement for more sustainable and higher-performance NR composites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.