Chitosan is soluble in most acids. The protonation of the amino groups on the chitosan backbone inhibits the electrospinnability of pure chitosan. Recently, electrospinning of nanofibers based on chitosan has been widely researched and numerous nanofibers containing chitosan have been prepared by decreasing the number of the free amino groups of chitosan as the nanofibiers have enormous possibilities for better utilization in various areas. This article reviews the preparations and properties of the nanofibers which were electrospun from pure chitosan, blends of chitosan and synthetic polymers, blends of chitosan and protein, chitosan derivatives, as well as blends of chitosan and inorganic nanoparticles, respectively. The applications of the nanofibers containing chitosan such as enzyme immobilization, filtration, wound dressing, tissue engineering, drug delivery and catalysis are also summarized in detail

A novel series of monodisperse bis-dipolar emissive oligoarylfluorenes, OF(2)Ar-NPh, bearing an electron affinitive core, 9,9-dibutylfluorene as conjugated bridges, and diphenylamino as end-caps was successfully synthesized by a convergent approach using palladium catalyzed Suzuki cross-coupling. The results of optical and electrochemical investigations showed that the HOMO, LUMO, and energy gap of these diphenylamino endcapped oligoarylfluorenes can easily be modified or tuned by the use of various electron affinitive central aryl cores that included dibenzothiophene, phenylene, oligothiophenes, 2,1,3-benzothiadiazole, 4,7-dithien-2-yl-2,1,3-benzothiadiazole, thiophene S,S‘-dioxide, and dibenzothiophene S,S‘-dioxide as well as the extent of the π-conjugated core. As a result, their emission bands measured in chloroform can cover the full UV−vis spectrum (from 412 to 656 nm). In contrast to the common dipolar chromophores, most of OF(2)Ar-NPhs can form morphologically stable amorphous thin films (T g = 88−127 °C) with a high decomposition temperature, T dec > 450 °C. Remarkably, undoped OF(2)Ar-NPh-based multilayer OLEDs could exhibit good to excellent device performance with emission colors spanning the full UV−vis spectrum. OF(2)Ar-NPh bearing oligothiophene core based devices exhibit a maximum luminance of 5000−12500 cd m-2 and luminous efficiency up to 3.6−4.0 cd A-1. Our findings provide a practical approach to design and tune the color emission of efficient and potentially useful light emitting materials.

Novel deep‐blue‐light‐emitting diphenylamino and triphenylamino end‐capped oligofluorenes were synthesized by double palladium‐catalyzed Suzuki cross‐coupling of dibromo‐oligofluorene with the corresponding boronic acid as a key step. These oligofluorenes exhibit deep‐blue emission (λemmax = 429–432 nm), low and reversible electrochemical oxidation (highest occupied molecular orbital = 5.15–5.20 eV), high fluorescence quantum yield (ΦFL = 0.61–0.93), and good thermal properties (glass‐transition temperature, Tg = 99–195 °C and decomposition temperature, Tdec > 450 °C). Remarkably, saturated deep‐blue organic light‐emitting diodes, made from these oligofluorenes as dopant emitters, have been achieved with excellent performance and maximum efficiencies up to 2.9 cd A–1 at 2 mA cm–2 (external quantum efficiency of 4.1 %) and with Commission Internationale de l'Éclairage (x,y) coordinates of (0.152,0.08), which is very close to the National Television System Committee standard blue.

A facile approach for synthesis of bipolar oligofluorenes, TAZ-OF(n)-NPh, n = 2 or 3 end-capped with hole-transporting diphenylamino and electron-transporting triazole moieties by Suzuki cross-coupling as the key reaction has been developed. This novel bipolar oligofluorenes exhibited blue-emission, high thermal and morphological stabilities. The single-layer OLED based on TAZ-OF(2)-NPh exhibited superior device performance with a maximum luminance of 1128 cd m(-2) and luminance efficiency of up to 0.83 cd A(-1).

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