Confined‐Volume Effect on the Thermal Properties of Encapsulated Phase Change Materials for Thermal Energy Storage

We have encapsulated the heat exchange material, n‐docosane, into polyurethane capsules of different sizes. Decreasing the size of the capsules leads to changes of the crystallinity of phase‐change material as well as melting/crystallization temperature. The novelty of the paper includes 1) protection of the nanostructured energy‐enriched materials against environment during storage and controlled release of the encapsulated energy on demand and 2) study of the structure and surface‐to‐volume properties of the energy‐enriched materials dispersed in capsules of different sizes. The stability of energy nanomaterials, influence of capsule diameter on their energy capacity, homogeneity and operation lifetime are investigated.     

An efficient synthetic approach towards new 5, 5'-diaryl-2, 2'-bipyridine-based fluorophores

An efficient approach has been developed for the synthesis of 5,5'-diaryl-2,2'-bipyridines via their 1,2,4-triazine analogues. The notable advantages of the present method are:The possibility of varying the aromatic substituents in the positions 5 and 5' of bipyridine core and the possibility for obtaining 2,2'-bipyridines bearing a fused cyclopentene core to increase the solubility in organic solvents. These 5,5'-diaryl-2,2'-bipyridines exhibited an intense emission in a range of ca. 422-521 nm in acetonitrile solution; depending on the nature of the aromatic substituents and the presence of annulated cyclopentene fragments. Apart from that, the significant bathochromic shifts of the both absorption and emission maxima were observed in comparison with a number of previously described similar structures. In some cases the significant increasing of the fluorescence quantum yields took place.