Cellulose ionic derivatives

It should also be noted that some nonradical ionic and condensation reactions of monomers with cellulose are used to modify the properties of cellulosic products. In one type of anionic-initiated reaction of monomers, cellulose is reacted with concentrated aqueous solutions of alkali metal hydroxides to yield cellulose copolymer. Free alkali metal in liquid ammonia or alkali metal alkoxides in nonaqueous systems may also be used as initiators of cellulose alkoxide derivatives. In cationic-initiated formation of copolymers, cellulose is reacted with an acid, such as boron trifluoride, to yield a cellulosic carbonium ion which initiates reactions with vinyl monomers. Condensation reactions of cyclic monomers with cellulose also form copolymers. Cellulose is usually slightly oxidized and also has reactive hydroxyl groups on carbons C-2, C-3 and C-6 of the anhydroglucose unit. The reactions of cyclic monomers are initiated at these carbonyl groups. A heating step may increase cellulosic oxidation and thereby increase the yield of these condensation products of cellulose and cyclic monomers." ... 

Paraformaldehyde/DMSO dissolves cellulose rapidly, with neghgible degradation, and forms the hydoxymethyl (methylol) derivative at Ce [ 140-142]. Therefore, cellulose derivatives at the secondary carbon atoms are easily obtained after (ready) hydrolysis of the methylol residue. Additionally, fresh formaldehyde may add to the methylol group, resulting in longer methylene oxide chains, that can be functionahzed at the terminal OH group, akin to non-ionic, ethylene oxide-based surfactants [143,144]. 

Polyelectrolytes (most notably ionic cellulose derivatives and crosslinked polyacid powders) are also commonly used as matrices, binders and excipients in oral controlled release compositions. In these applications, the polyelectrolytes provide hydrophilicity and pH sensitivity to tablet dosage forms. Acidic polyelectrolytes dissociate and swell (or dissolve) at high pH values whereas basic polyelectrolytes (for instance, polyamines) become protonated and swell at low pH. In either case, swelling results in increased permeability [290], thereby allowing an incorporated drug to be released. 

P3. Porath, J., Zone Electrophoresis in Columns and Adsorption Chromatography on Ionic Cellulose Derivatives, as Methods for Peptide and Protein Fractionations. Almqvist and Wiksells, Uppsala, 1957. 

Quite recently, a series of N-alkyl substituted imidazolium salts has been evaluated for additive effects on the mesomorphic behavior and ensuing optical properties of HPC aqueous solutions, followed by characterization of the thermotropicity of novel cellulose derivatives with such an ionic liquid structure in the side-chains [193]. 

The effect of heat on the polysaccharide-water interaction in several dispersions and suspensions was studied by comparative viscometry and rheometry (Tables I-IV). The polysaccharides were the purest manufacturers grade laboratory washed and dried before dispersion. The dispersion concentrations were below c to accommodate capillary viscometry, and the suspension concentrations were above c to accommodate rheometry. It is seen in Tables I and II that the cellulose derivatives made the most stable dispersions and the propylene glycol alginate made the least. Dispersions of the neutral polysaccharides were more stable than those of the ionic polysaccharides. From Tables III and IV, it can be argued that suspensions benefit... 

Being ionic compounds, cellulose sulfates have ion exchange properties. They have been recommended for use as cation exchangers [42,47,48]. Sodium ceilulose sulfates are also known to have blood anticoagulant activity. The correlation of molecular characteristics of these derivatives with their anticoagulant activity has been investigated [49]. However, it has been reported that celiuiose suifate exhibits a certain toxicity [50]. 

For the analysis of water-soluble polymers (such as surfactants, oligosaccharides, PEGS, lignosulfonates, polyacrylates, polysaccharides, PVA, cellulose derivatives, PEG, polyacrylic acids, polyacrylamides, hyaluronic acids, CMC, starches, gums) and for separations of oligomers and small molecules, columns that are comprised of macroporous material with hydrophilic functionalities may be used. The requirement for these columns in SEC mode is to eliminate or minimize ionic and hydrophobic effects that make aqueous SEC (otherwise known as GFC) very demanding. The interaction of analytes with neutral, ionic, and hydrophobic moieties must be suppressed. It is often necessary to modify the eluent (addition of salt) in order to avoid sample-to-sample and sample-to-column interactions that can result in poor aqueous SEC separations and low recoveries. 

The present work summarizes the some results of these studies. The article describes some new types of cellulose etho and esters, a number of mixed polysaccharides based on cellulose, which have been synthesized by the authors and their coworkers, and also discusses the principles governing a number of reactions for effecting tte chemical transformatiem of cellulose, i.e. nucleophilic sutetitution, trtms-esterifica-tiem, ionic and free-radical additimi, which enable new types d cellulose derivatives to be synthesized. 

Because the double bond in the repeating units of tte macromolecule of 5,6-cellulosene is polarize4 this derivative of cellulose readily enters into chemical reactions proceeding by various mechanisms. In particular, the addition of methanol or acetic acid, when the reaction proceeds under mild conditions by an ionic mechanism, yields a mixed polysaccharide containing 5-O-methyl- or 5-O-acetylisoramnonose, respectively 43) ... 

Since cellulose and cellulose derivatives have found wide acceptance in the cosmetic, pharmaceutical and medical industries, much work is currently focusing on highly selective modification of cellulose ethers (as well as cellulose esters) for highly targeted controlled release characteristics. Interaction with water, and interaction with a variety of co-substrates under conditions varying in temperature, ionic strength, pH, etc., has opened avenues for the use of cellulose ethers in drug delivery. This field has recently been reviewed [78,79]. 

A broader exploitation of cellulose solubility in ionic liquids lies in modification of cellulose into more useful forms. Cellulose acetate is currently the most useful derivative of cellulose, with uses in photographic film, as a synthetic fibre and as a component of adhesives. Acetylation of cellulose has been carried out effectively in l-allyl-3-methylimidazolium chloride [Amim][Cl], [C4mim CI], [C2mim][Cl], l-butyl-2,3-dimethylimidazolium chloride [C4dmim][Cl] and l-allyl-2,3-dimethyl-imidazolium bromide [Admim][Br] [136, 159-162], The first report of cellulose acetylation in an ionic liquid involved a one-step reaction in [Amim][Cl] without catalyst, yielding cellulose acetate with a controllable degree of substitution [136], Yields of cellulose acetate of up to 86% have been obtained via reaction in [C4mim] [Cl] at 80 °C for 2 h [160],... 

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