Size Effects of Nano-crystalline Cellulose

Natural cellulose with the crystal form of cellulose I, when treated with condensed lye(e.g. 18% NaOH), can change into new crystal form of cellulose II. But the nano-crystaUinecellulose (NCC) can do it when only treated with dilute lye (e.e. 4%NaOH) at room temperature and even can dissolve into slightly concentrated lye (e.g.4%NaOH).     

Immobilization of Glucose Oxidase on Cellulose／Cellulose Acetate Membrane and its Detection by Scanning Electrochemical Microscope （SECM）

Cellulose/cellulose acetate membranes were prepared and functionalized by introducingamino group on it, and then immobilized the glucose oxidase (Gox) on the functionalizd membrane.SECM was applied for the detection of enzyme activity immobilized on the membrane.Immobilized biomolecules on such membranes was combined with analysis apparatus and can beused in bioassays.     

Nanocellulose Materials – Different Cellulose,Different Functionality

Summary: Nanocelluloses combine in a very exciting manner important properties of cellulose with amazing features of nano-scale materials. With a view to the increasing discussion on the potential risks of nanoparticles and nanotechnology to human health and the environment, it is important to point out that the nanocellulose fibers are irreversibly networked in the supramolecular cellulose structure. This contribution assembles the current knowledge in research, development, and application in the field of nanocelluloses through examples. The topics combine selected results on nanocelluloses from bacteria and wood as well as the formation and in situ shaping of cellulose bodies, the coating of materials with nanosized cellulose networks/supports, and the preparation of nanocellulose composites as well as the use of bacterial cellulose as novel type of medical implants.     

Enantiomeric Separation of Four Chiral Compounds Using Immobilized Cellulose 3, 5-Dimethylphenylcarbamate as Chiral Stationary Phase

The increasing demands for the production of enantiomerically pure compounds in the field of pharmacology, chemistry, biotechnology, chemical engineering, etc., have made enantioselective separations to become one of the most important analytical tasks. H…     

Mit der Mikrobestimmung von Alkoxylgruppen in Cellulose?thern

Ohne Zusammenfassung     

Carboxymethyl Ethers of Cellulose and Starch – A Review

This review article deals with the technically important carboxymethyl ethers of cellulose and starch. Recent developments of synthesis, characterization, and application are presented considering adequately own research work in this field. In particular, the structure characterization by means of chromatographic (HPLC) and NMR-spectroscopic techniques as well as commercially important synthesis paths and alternative methods are described.     

Cellulose–halloysite nanotube composite hydrogels for curcumin delivery

Halloysite nanotubes (HNTs) were added to cellulose NaOH/urea solution to prepare composite hydrogels using epichlorhydrine crosslinking at an elevated temperature. The shear viscosity, mechanical properties, microstructure, swelling properties, cytocompatibility, and drug delivery behavior of the cellulose/HNT composite hydrogels were investigated. The viscosity of the composite solution increases with the addition of HNT. The compressive mechanical properties of composite hydrogels are significantly improved compared with pure cellulose hydrogel. The compressive strength of the composite hydrogels with 66.7% HNTs is 128 kPa, while that of pure cellulose hydrogel is only 29.8 kPa in compressive strength. Rheological measurement suggests the resistance to deformation is improved for composite hydrogels. X-ray diffraction and Fourier transform infrared spectroscopy show that the crystal structure and chemical structure of HNT are not changed in the composite hydrogels. Hydrogen bonding interactions between HNT and cellulose exist in the composites. A porous structure of the composite hydrogels with pore size of 200–400 μm was found by scanning electron microscopy. The addition of HNT leads to decreased swelling ratios in NaCl solution and pure water for the composite hydrogels. Cytotoxicity assays show that the cellulose/HNT composite hydrogels have a good biocompatibility with MC3T3-E1 cells and MCF-7 cells. Curcumin is further loaded into the composite hydrogel via physical adsorption. The curcumin-loaded composite hydrogels show a strong inhibition effect on the cancer cells. All the results illustrate that the cellulose/HNT composite hydrogels have promising applications such as anticancer drug delivery systems and anti-inflammatory wound dressings.     

Die Hydrolyse von Cellulose in starker Schwefels?ure

Ohne Zusammenfassung     

Cellulose Peroxides with Structures of Peracid and α-Hydroxyhydroperoxide Types

Cellulose peroxides derived from various cellulose derivatives with hydrogen peroxide were investigated. Fibrous carboxy-methyl cellulose, periodic acid-oxidized cellulose, and methyl vinyl ketone-treated cellulose were employed as cellulose derivatives. Carboxyl and carbonyl groups in the cellulose derivatives were believed to react with hydrogen peroxide to form peroxides with structures of peracid and α-hydroxyhydroperoxide types, respectively. The decomposition of the cellulose peroxides and their abilities to initiate grafting reaction were examined.     

Cellulose–silica composite aerogels from “one-pot” synthesis

Cellulose–silica composite aerogels were prepared via “one-pot” process: aqueous solutions of cellulose–8 wt% NaOH and sodium silicate were mixed, coagulated and dried with supercritical CO₂. The system was studied both in the fluid and solid (dry) states. Cellulose and sodium silicate solutions were mixed at different temperatures and concentrations; mixture properties were monitored using dynamic rheology. The gelation time of the mixture was strongly reduced as compared to that of cellulose–NaOH solutions; we interpret this phenomenon as cellulose self-aggregation inducing partial coagulation due to competition for the solvent with sodium silicate. The gelled cellulose/sodium silicate samples were placed in aqueous acid solution which completed cellulose coagulation and led to in situ formation of sub-micronic silica particles trapped in a porous cellulose matrix. After drying with supercritical CO₂, an organic–inorganic aerogel composite was formed. The densities obtained were in the range of 0.10–0.25 g/cm³ and the specific surface area was between 100 and 200 m²/g. The silica phase was shown to have a reinforcing effect on the cellulose aerogel, increasing its Young’s modulus.     

Cellulose in NaOH–water based solvents: a review

The article is a critical review of all aspects of the dissolution of cellulose in NaOH-based aqueous solutions: from the background properties of the solvent itself, to the mechanisms of cellulose fibre swelling and dissolution, solution structure and properties and influence of additives and, finally, to the properties of various materials (fibres, films, aerogels, composites and interpenetrated networks) prepared from these solutions. A historical evolution of the research on this topic is presented. The pros and cons of NaOH-based aqueous solvent for cellulose are summarised and some prospects are suggested.     

The Adsorption of Aqueous—Organic Mixture Components on Cellulose

The isotherms of composition changes were obtained for the cellulose—water—dimethylsulfoxide and cellulose—water—acetonitrile systems. The isotherms of sorption of aqueous—organic mixture components on cellulose were calculated. The heat effects of wetting of cellulose with water—dimethylsulfoxide and water — acetonitrile solutions were measured. The special features of sorption of the components on cellulose were shown to be related to the character of cluster formation in the binary systems under consideration.     

Interactions of Ionic Liquids with Polysaccharides – 2: Cellulose

Some general comments about ionic liquids (ILs) and carbohydrates are given. The main scope of the review is to discuss the present state of the art of chemical modification of cellulose applying IL as reaction media considering own research results. ILs, namely 1-butyl-3-methylimidazolium chloride (BMIMCl), 1-ethyl- 3-methylimidazolium chloride (EMIMCl), 1-butyl-2,3-dimethylimidazolium chloride (BDMIMCl), 1-allyl-2,3-dimethylimidazolium bromide (ADMIMBr) and 1-ethyl-3- methylimidazolium acetate (EMIMAc) are solvents for cellulose (even for high molecular bacterial synthesized cellulose) and can easily be applied as reaction media for cellulose modification. We investigated the homogeneous acylation, carbanilation and silylation of the biopolymer cellulose. Under mild conditions and within short reaction time at low temperature (65 °C to 80 °C) and low excess of reagent, various cellulose esters and carbanilates, dendronized cellulose and trimethylsilyl cellulose were obtained. The DS of the cellulose derivatives can be controlled by varying the reaction time, reaction temperature and the IL used as reaction medium.     

Contributions to Forming and Analytical Investigations of Solutions of Cellulose and Cellulose Derivatives – A Research and Development Topic of the TITK eV

Modification, forming and analytical characterisation of cellulose and cellulose solutions represents one of the most important research topics of the Thuringian Institute for Textiles and Plastics Research (TITK). The presentation provides information on the current capabilities of the institute and on the analytical methods developed in these fields.     

Eine R?ntgenstudie an partiell ox?thylierter Cellulose

Ohne Zusammenfassung     

Über die Darstellung einiger Fettsäureester der Cellulose

Zusammenfassung Aus handelsüblichen Baumwoll-Linters wurden Celluloseester der Buttersäure, Valeriansäure, Capronsäure, Caprylsäure und Pelargonsäure mit einem durchschnittlichen Veresterungsgrad von 2,4–2,6 Acylgruppen pro Glucoseeinheit dargestellt. Durch geeignete Wahl der Reaktionsbedingungen, besonders der pro OH-Gruppe eingesetzten Pyridinmenge, können im löslichen Anteil des Reaktionsprodukts Celluloseester mit bestimmten Durchschnittspolymerisationsgraden erhalten werden (Tab. 6).Jetzt Bundesanstalt für Materialprüfung.     

Cellulose Solubility in Deep Eutectic Solvents: Inspecting Quantitative Hydrogen-Bonding Analysis

According to the Kamlet-Abraham-Taft(KAT) polarity parameters(α, β, π^*), polymers and solvents can be categorized as hydrogenbond(H-bond) acidic(α>β) or H-bond basic(α<β). Recently, we proposed a quantitative hydrogen bonding(QHB) analysis to predict the solubility of polymers in ionic liquids(ILs) using the product of ΔαΔβ<0 as an indicator, where Δα is the difference between the H-bond acidic parameters of the polymer and IL, and Δβ is the difference in their basicity, whil...     

Functional Cellulose Materials Fabricated by Using Ionic Liquids as the Solvent

Cellulose is one of the most abundant natural polymers in the nature, which has many attractive advantages, such as renewability,biodegradability, and biocompatibility. However, due to the strong hydrogen bond network and hierarchical structure, cellulose is extremely difficult to be dissolved and processed. More recently, a class of novel eco-friendly solvents, ionic liquids, have been found to be able to efficiently dissolve cellulose, providing a versatile platform for cellulose processing an...