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Dong, Xue Min; Revol, J.‐F.; Gray, Derek G.

doi:10.1023/a:1009260511939

Cited by 958 publications

(660 citation statements)

References 15 publications

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“…Acetone, dimethyl formamide (DMF), and sulfuric acid were purchased from Fisher Scientific. EPON 828 and EPIKURE W ( Figure 1) were received from Miller-Stephenson Chemical Company, Inc. Cellulose whiskers from cotton were isolated using the general procedure of Dong et al (39) with slight modifications as described in detail before (21); the concentration of the aqueous whisker dispersion produced was determined gravimetrically to be ∼20 mg/mL. Cellulose whiskers from tunicates were isolated using the general procedure of Favier et al with slight modifications (21); the concentration of the aqueous whisker dispersion produced was determined gravimetrically to be ∼8 mg/mL.…”

Section: Methodsmentioning

confidence: 99%

Cellulose Whisker/Epoxy Resin Nanocomposites

Tang

Weder

2010

ACS Appl. Mater. Interfaces

233

188

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New nanocomposites composed of cellulose nanofibers or "whiskers" and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of ∼10 and ∼84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight of 185-192 and a diethyl toluenediamine-based curing agent. Thin films were produced by casting these mixtures and subsequent curing. The whisker content was systematically varied between 4 and 24% v/v. Electron microscopy studies suggest that the whiskers are evenly dispersed within the epoxy matrix. Dynamic mechanical thermoanalysis revealed that the glass transition temperature (T g ) of the materials was not significantly influenced by the incorporation of the cellulose filler. Between room temperature and 150°C, i.e., below T g , the tensile storage moduli (E′) of the nanocomposites increased modestly, for example from 1.6 GPa for the neat polymer to 4.9 and 3.6 GPa for nanocomposites comprising 16% v/v tunicate or cotton whiskers. The relative reinforcement was more significant at 185°C (i.e., above T g ), where E′ was increased from ∼16 MPa (neat polymer) to ∼1.6 GPa (tunicate) or ∼215 MPa (cotton). The mechanical properties of the new materials are well-described by the percolation model and are the result of the formation of a percolating whisker network in which stress transfer is facilitated by strong interactions between the whiskers.

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Section: Methodsmentioning

confidence: 99%

Cellulose Whisker/Epoxy Resin Nanocomposites

Tang

Weder

2010

ACS Appl. Mater. Interfaces

233

188

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“…On the other hand, for the whiskers obtained from SCB under more severe hydrolysis conditions, with 65% H 2 SO 4 (w/w) at 55 °C for 75 min, the size obtained by DLS was 167 ± 2 nm, which indicates that the hydrolysis conditions can alter [39] the dimensions and surface characteristics of the whiskers, as well as their yield. Thus, it is possible to control the aspect ratio (L/D) and surface area, which are important characteristics of nanocrystals, making them of interest for different applications.…”

Section: Characterization Of Whiskersmentioning

confidence: 94%

“…On the other hand, Oksman and Bondeson et al [38] carried out hydrolysis with H 2 SO 4 (63.5% w/w), using a 10:1 (v/w) solution/raw material ratio and a reaction time of 2 h and obtained whiskers with a yield of 30%. Dong et al [39] reported yields of between 35% and 48% when varying the hydrolysis conditions (64% H 2 SO 4 w/w) applying temperatures of 26 °C to 65 °C and reaction times of between 0.25 h and 18 h. Mathew et al [40] studied wood waste from the production of ethanol, after bleaching and acid hydrolysis and recorded 46% yield for the whiskers. In this regard, we also conducted preliminary experiments under more severe conditions, with 65% H 2 SO 4 (w/w), a temperature of 55 °C and 75 min of reaction and with 60% H 2 SO 4 (w/w) at 55 °C for 300 min, and in both cases the yield of whiskers obtained was 30%.…”

Section: Evaluation Of the Effect Of Bleaching Processmentioning

confidence: 99%

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

et al. 2016

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SbstractWhiskers have been used as a nanomaterial dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents.

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“…Therein, tuning of nanoparticle concentrations, sizes and charge screening is central. The CD signal is reproduced using numerical simulations utilizing the AuNP coordinates from cryo-ET.CNCs were prepared from cotton filter paper (Whatman 1) using sulfuric acid hydrolysis [44,45] , leading to anionic sulfate ester groups on their surface (Scheme 1). The surface charge was 0.36 eq/kg by conductometric titration as corresponding to a charge density of 0.6 e/nm 2 .…”

mentioning

confidence: 99%

“…CNCs were prepared from cotton filter paper (Whatman 1) using sulfuric acid hydrolysis [44,45] , leading to anionic sulfate ester groups on their surface (Scheme 1). The surface charge was 0.36 eq/kg by conductometric titration as corresponding to a charge density of 0.6 e/nm 2 .…”

mentioning

confidence: 99%

Chiral Plasmonics Using Twisting along Cellulose Nanocrystals as a Template for Gold Nanoparticles

et al. 2016

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Nanocelluloses with native crystalline internal structures have attracted considerable interest due to their plant-based origin, high mechanical properties, modifiability, and chiral liquid crystallinity, which suggest novel functional sustainable materials. [1−27] In particular, cellulose nanocrystals (CNCs) are colloidal rods, having a typical lateral dimension of 5−10 nm and length of 50−300 nm. Above a critical aqueous concentration, they exhibit lefthanded chiral nematic (cholesteric) liquid crystallinity (LC) and optical iridescence, [4][5][6] which is preserved in dried films [4,28] . It allows templating for photonic materials using inorganics, nanoparticles, polymers, and pyrolyzed carbonized matter. [10,12,16,25,26] On the other hand, the CNCs have been suggested to possess a right-handed twist along their nanorod axis to explain the left-handed twist in their chiral LC. [6] Recently, the right-handed twist of individual CNCs and nanocelluloses of three different origins was observed by cryo-electron tomography (cryo-ET), and electron and atomic force microscopy [27,29] supported by molecular dynamics simulations [30−32] .Exploiting the twisting shape along the individual CNC nanorods could allow new optical functions in the nano/colloidal scale in dilute aqueous dispersions, i.e. not limited to the chiral LC based on the inter-rod assembly involving a larger length scale. Surprisingly, such optical findings have not been reported so far.Surface plasmons, i.e. collective oscillations of the conduction electrons on metal surfaces, allow physics and applications ranging from photonic devices, sensing, and solar cells to pharmacology. [33−37] In nanoparticles (NPs) the oscillations become coupled to allow a chiral plasmonic response, provided that they are sufficiently closely positioned and assembled in a chiral manner. This manifests in circular dichroism (CD) spectroscopy, which describes the difference in absorption between left-and right-handed circularly polarized light. The chiral coupling of surface plasmons induces a bisignated CD signal with a zerocrossing at the characteristic localized surface plasmon resonance wavelength of the isolated NPs. Such a Cotton effect is either dip−peak or peak−dip, depending on the handedness of chirality. [38−42] In chiral biological molecules, such as DNA, proteins and polypeptides, the CD signal is at ultraviolet wavelengths, whereas the CD signal of helical metal nanoparticle assemblies is at the visible wavelengths. This extends the applications to e.g. in biosensing. [37] Chiral nanoparticle assemblies have been shown using helical polymers, supramolecular fibers, and DNA-based constructs as templates. [40−42] In particular, a chiral plasmonic signal is obtained using DNA-origami to organize the nanoparticles in well-defined helices with tunable pitch, separation, and handedness. [40,41] Even if the above approaches are promising allowing in-depth tunable chiral plasmonic response, introducing rapid, scalable, and economic ways for producing chiral plas...

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Untitled

Cited by 958 publications

References 15 publications

Cellulose Whisker/Epoxy Resin Nanocomposites

Cellulose Whisker/Epoxy Resin Nanocomposites

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Chiral Plasmonics Using Twisting along Cellulose Nanocrystals as a Template for Gold Nanoparticles

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