Persistent luminescence from purely organic materials is basically triggered by light and electricity, which largely confines its practical applications. A purely organic AIEgen exhibits not only persistent photoluminescence, but also transient and persistent room-temperature mechanoluminescence. By simply turning on and off a UV lamp, tricolor emission switching between blue, white, and yellow was achieved. The data from single-crystal structure analysis and theoretical calculation suggest that mechanism of the observed persistent mechanoluminescence (pML) is correlated with the strong spin-orbit coupling of the bromine atom, as well as the formation of H-aggregates and restriction of intramolecular motions in noncentrosymmetric crystal structure. These results outline a fundamental principle for the development of new pML materials, providing an important step forward in expanding the application scope of persistent luminescence.
Controllable synthesis of graphite oxide (GO) for targeted surface properties is of great importance for its versatile applications. For this purpose, GO samples were prepared with different amounts of oxidant and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, 13 C cross-polarization with total sideband suppression magic-angle-spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, Raman spectroscopy, and ζ-potential measurement. When the oxidant amount is below a critical value, the epoxy groups are dominant on the GO surfaces, together with a few hydroxyl and carbonyl groups. Further increase in the oxidant amount leads to the formation and development of the carboxyl groups, which eventually reach a saturation level. Meanwhile, the increasing oxygen-containing groups introduce more defects and reduce the crystalline graphene domains on GO. A possible mechanism for the formation of the oxygen-containing groups on GO is proposed, providing a guideline for the manipulation of the GO surface properties.
Persistent luminescence from purely organic materials is basically triggered by light and electricity,w hichl argely confines its practical applications.Apurely organic AIEgen exhibits not only persistent photoluminescence,b ut also transient and persistent room-temperature mechanoluminescence.B ys imply turning on and off aU Vl amp,t ricolor emission switching between blue,w hite,a nd yelloww as achieved. The data from single-crystal structure analysis and theoretical calculation suggest that mechanism of the observed persistent mechanoluminescence (pML) is correlated with the strong spin-orbit coupling of the bromine atom, as well as the formation of H-aggregates and restriction of intramolecular motions in noncentrosymmetric crystal structure.These results outline af undamental principle for the development of new pML materials,p roviding an important step forward in expanding the application scope of persistent luminescence.
A series of novel triblock copolymers of poly(stearyl methacrylate)-b-poly(N-isopropylacrylamide)-b-poly(stearyl methacrylate) (PSMA-b-PNIPAAm-b-PSMA) with different molecular weights was synthesized through carboxyl-terminated trithiocarbonates as a highly efficient RAFT agent via reversible addition-fragmentation chain transfer (RAFT) polymerization. The resultant polymers were characterized by 1H NMR, FT-IR spectroscopy, and GPC. By varying the organic solvent used in the self-assembly procedure and adjusting the copolymer composition, multiple morphologies ranging from vesicles and core-shell spherical aggregates with different dimensions to pearl-necklace-like aggregates were obtained. The aggregates showed thermoresponsive and pH-responsive properties through the lower critical solution temperature (LCST) of PNIPAAm and the two carboxyl end groups of the copolymer.
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