Abstract:Carbazole-substituted hydroxyethylcelluloses (Cz-HECs) are homogeneously synthesized by reacting hydroxyethylcellulose (HEC) with N -3 ′ -bromopropyl carbazole (Br-Cz). The structure of Cz-HECs is characterized with elemental analysis and NMR, and the DS of the carbazole is in the range 0.11-0.43, determined from nitrogen content. The fl uorescent properties of Cz-HECs are measured using a spectrofl uorimeter. The results show that the fl uorescence lifetime increases as the DS increases, and the fl uorescent … Show more
“…[25] Zhang et al have homogeneously synthesized carbazole-substituted hydroxyethyl cellulose (HEC) where, by increasing the cellulose degree of substitution with carbazole, the fluorescence lifetime was increased. [26] The fluorescent intensity of carbazole-substituted hydroxyethyl cellulose was also found to be stronger than for the carbazole derivative itself. At the same time, coumarin derivatives are important fluorescent dyes with high photoluminescence quantum efficiencies, and uses in optoelectronic materials, while they also display anti-tumoral, anti-coagulant, and anti-oxidant properties.…”
Section: Introductionmentioning
confidence: 94%
“…[25] Zhang et al have homogeneously synthesised carbazole-substituted hydroxyethyl cellulose (HEC) where, by increasing the cellulose degree of substitution with carbazole, the fluorescence lifetime was increased. [26] The…”
This article is protected by copyright. All rights reserved Fluorescent cellulose nanocrystals with carbazole and coumarin functionalities were synthesised in a one-step esterification reaction using carbazole-9-yl-acetic acid and coumarin-3-carboxylic acid respectively, using a p-toluenesulfonyl chloride/pyridine system. Characterization with elemental analysis, X-ray diffraction, X-ray photoelectron spectroscopy, infrared, absorption and emission spectroscopy, and AFM and TEM imaging confirmed that a high degree of modification could be achieved (up to DS surf = 1.33) while retaining the CNC core crystallinity and nanoparticle dimensions. The present grafting method gives a straightforward way when compared with previously reported fluorescent labelling methodologies and gives an extremely high grafting density while retaining the CNC crystallinity. UV spectroscopy also indicates fluorescence quenching at high grafting densities so that optimal fluorescence does not necessarily mean maximum grafting density. This
“…[25] Zhang et al have homogeneously synthesized carbazole-substituted hydroxyethyl cellulose (HEC) where, by increasing the cellulose degree of substitution with carbazole, the fluorescence lifetime was increased. [26] The fluorescent intensity of carbazole-substituted hydroxyethyl cellulose was also found to be stronger than for the carbazole derivative itself. At the same time, coumarin derivatives are important fluorescent dyes with high photoluminescence quantum efficiencies, and uses in optoelectronic materials, while they also display anti-tumoral, anti-coagulant, and anti-oxidant properties.…”
Section: Introductionmentioning
confidence: 94%
“…[25] Zhang et al have homogeneously synthesised carbazole-substituted hydroxyethyl cellulose (HEC) where, by increasing the cellulose degree of substitution with carbazole, the fluorescence lifetime was increased. [26] The…”
This article is protected by copyright. All rights reserved Fluorescent cellulose nanocrystals with carbazole and coumarin functionalities were synthesised in a one-step esterification reaction using carbazole-9-yl-acetic acid and coumarin-3-carboxylic acid respectively, using a p-toluenesulfonyl chloride/pyridine system. Characterization with elemental analysis, X-ray diffraction, X-ray photoelectron spectroscopy, infrared, absorption and emission spectroscopy, and AFM and TEM imaging confirmed that a high degree of modification could be achieved (up to DS surf = 1.33) while retaining the CNC core crystallinity and nanoparticle dimensions. The present grafting method gives a straightforward way when compared with previously reported fluorescent labelling methodologies and gives an extremely high grafting density while retaining the CNC crystallinity. UV spectroscopy also indicates fluorescence quenching at high grafting densities so that optimal fluorescence does not necessarily mean maximum grafting density. This
“…2f, the QY of BSKP, CNF-0, CNF-1, CNF-2 and CNF-3 were 35.5%, 20.5%, 23.6%, 21.7% and 18.2%, respectively. One of the reasons for the decrease in fluorescence intensity and QY may be due to the introduction of carboxyl groups which acted as an electron acceptor which weakened the flow of π electrons in the system and then limited the fluorescence property [15][16][17] .…”
Section: Resultsmentioning
confidence: 99%
“…2 f, the QY of BSKP, CNF-0, CNF-1, CNF-2 and CNF-3 were 35.5%, 20.5%, 23.6%, 21.7% and 18.2%, respectively. One of the reasons for the decrease in fluorescence intensity and QY may be due to the introduction of carboxyl groups which acted as an electron acceptor which weakened the flow of π electrons in the system and then limited the fluorescence property 15 – 17 . Figure 2 Fluorescence spectrum with inset showing the fluorescence pictographs (EX: excitation spectrum, EM: emission spectrum) of ( a ) BSKP, ( b ) CNF-1, ( c ) CNF-2, ( d ) CNF-3.…”
This work explored the fluorescence properties of nano/cellulose isolated from bleached softwood kraft pulp by TEMPO oxidation. Fluorescence spectra showed that all samples exhibited a typical emission peak at 574 nm due to the probabilistic formation of unsaturated bonds by glycosidic bonds independent of lignin. Increasing the excitation wavelengths (510–530 nm) caused red shift of fluorescence emission peaks (570–585 nm) with unchanged fluorescence intensity. Conversely, changing acid/alkaline conditions led to an increase of fluorescence intensity with no shifting of fluorescence emission peak. This can be attributed to an increase in the polarity of the solution environment but does not cause interaction of functional groups within the system identified by generalized two-dimensional correlation fluorescence spectroscopy. This study provides new insight in applying nano/cellulose with special luminous characteristics in biomedicine area such as multi-color biological imaging and chemical sensing.
“…Chemical alteration of cellulose is often used to modify the performance of cellulose for specific applications. To this end, several strategies have been developed, including homogeneous [ 9 , 10 , 11 ] and heterogeneous conditions [ 12 , 13 , 14 ]. Despite the use of cellulose on a large scale, many potential applications of cellulose derivatives are limited by their hygroscopic properties because of the change in the cellulose chemical structure.…”
Abstract:The hydrophilic property of cellulose is a key limiting factor for its wide application. Here, a novel solution impregnation pathway was developed to increase the hydrophobic properties of cellulose. When compared with the regenerated cellulose (RC), the composite films showed a decrease in water uptake ability towards water vapor, and an increase of the water contact angle from 29 • to 65 • with increasing resin content in the composites, with only a slight change in the transmittance. Furthermore, the Young's modulus value increased from 3.2 GPa (RC film) to 5.1 GPa (RCBEA50 film). The results indicated that the composites had combined the advantages of cellulose and biphenyl A epoxy acrylate prepolymer (BEA) resin. The presented method has great potential for the preparation of biocomposites with improved properties. The overall results suggest that composite films can be used as high-performance packaging materials.
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