RESUMO
Because of their exceptional physical and thermal properties, cellulose nanocrystals (CNCs) are a highly promising bio-based material for reinforcing fillers. Studies have revealed that some functional groups from CNCs can be used as a capping ligand to coordinate with metal nanoparticles or semiconductor quantum dots during the fabrication of novel complex materials. Therefore, through CNCs ligand encapsulation and electrospinning, perovskite-NC-embedded nanofibers with exceptional optical and thermal stability are demonstrated. The results indicate that, after continuous irradiation or heat cycling, the relative photoluminescence (PL) emission intensity of the CNCs-capped perovskite-NC-embedded nanofibers is maintained at ≈90%. However, the relative PL emission intensity of both ligand-free and long-alkyl-ligand-doped perovskite-NC-embedded nanofibers decrease to almost 0%. These results are attributable to the formation of specific clusters of perovskite NCs along with the CNCs structure and thermal property improvement of polymers. CNCs-doped luminous complex materials offer a promising avenue for stability-demanding optoelectronic devices and other novel optical applications.
RESUMO
The skin-core evolvement of the carbon fibers was studied as a function of heat-treatment temperature though the analysis of Raman spectroscopy of the carbon fibers surface and core. It was found that the change of the Raman spectra of the carbon fibers core was similar to that on the surface with the increase in heat-treatment temperature. At 1600 degrees C, the Rs and Rc values were almost equal, indicating that the degrees of the graphitization of the carbon fibers surface and core were almost uniform. The Rs and Rc values decreased dramatically with the increase in heat-treatment temperature, and Rs decreased more. At 2800 degrees C, the Rs value came to 0.429, lowered 77.2%, while the Rc value then came to 1.101, lowered 38.7% only. It implied that the graphitization degree of the carbon fibers was enhanced with increasing the heat treatment temperature, and that of carbon fibers surface was enhanced more. The graphite characters of the carbon of the carbon fibers surface were different from that of the carbon fibers core. The former is close to soft carbon, which is easy to graphitize, while the latter is close to hard carbon, which is difficult to graphitize, and it may be resin carbon Skin-core structure gene Rsc (= Rs/Rc) which denoted the skin-core degree of the carbon fibers was first brought forward and adopted. The Rsc value is between 0 and 1. When the Rsc value is equal to 1, the carbon fibers are homogenous. When the Rsc value is close to zero, there are serious skin-core structures in the carbon fibers. The Rsc value reduced linearly with the increase in heat-treatment temperature, indicating that the homogeneous degrees of the carbon fibers decreased and the skin-core degrees of the carbon fibers increased. The crystallite size of the carbon fibers surface and core increased gradually with the increase in heat-treatment temperature, but the surface's increased more quickly, indicating that the carbon of the carbon fibers surface was easier to graphitize than the carbon fibers core. Serious skin-core structure was one of the reasons that caused the reducing of the carbon fibers' tensile strength.