Hydroxyethylcellulose solubility

Another approach to improving the wettability of poorly soluble drugs is to treat the drug with a solution of a hydrophilic polymer. Lerk et al. [137] reported that both wettability of the powder and the rate of dissolution of hexobarbital from hard gelatin capsules could be greatly enhanced if the drug were treated with methylcellulose or hydroxyethylcellulose. In this process, called hydrophilization, a solution of the... 

The water-soluble hydroxyethylcellulose has only a limited use as compared to water-soluble methylcellulose, principally because of the difficulty of isolating the product. Aqueous solutions of hydroxyethylcellulose do not gel on heating and the product is about as soluble in hot water as in cold, so that the method used for isolating water-soluble methylcellulose is not applicable. However, by dialyzing the reaction product the alkali and salts may be removed and the product isolated. 

The properties of hydroxyethylcellulose are like those of methylcellulose except for the fact that there is little or no temperature effect on solubility. The degree of substitution required to impart water solubility will depend both upon the degree of polymerization of the cellulose and upon the uniformity of substitution. It is of interest... 

The low-substituted hydroxyethylcellulose which, like methyl- and ethylcellulose, is soluble in alkali, particularly when cooled, has much to recommend it from an industrial point of view. It can be formed by the action of only small quantities (0.25 to 0.5 moles) of ethylene oxide on alkali cellulose.47 The reaction product need not be isolated since there are no salts formed, but may be diluted with water or weak alkali to give a spinning solution. The product should therefore be quite cheap. Preparation and properties of hydroxyethylcellulose have been discussed by Schorger and Shoemaker.47... 

Cellulose derivatives, e.g. hydroxyethylcellulose, are used in the formulation of sustained release tablets and suspensions. Natrosol (hydroxyethylcellulose) is a nonionic water-soluble polymer that is extensively used as a thickener. 

In general, the MS controls the solubility of both HEC and HPC. For example, water-soluble grades of hydroxyethylcellulose have MS values of 1.6—3.0 those with MS 0.3—1.0 are soluble in aqueous alkali. Even higher MS types of hydroxypropylcellulose become soluble in oiganic solvents, first polar, then nonpolar solvents. 

Clear, water-soluble, oil-and grease-resistant films of moderate strength can be cast from hydroxyethylcellulose solutions. Flexible, nontacky, heat-sealable packaging films and sheets can be produced from hydroxypropylcellulose by conventional extrusion techniques. Both gums can be used in the formulation of coatings, and both can be used to form edible films and coatings. 

Within this group, the linear polymers have been most intensively studied and researched. The main area of interest lies in water-soluble polymers. However, there have also been many studies into organic solutions, although there exist problems with odor and toxicity in the case of analytical studies. Among the water-soluble additives, tests were made especially on polyethyleneoxide (PEO), polyacrylamide and the coacrylates (PAAm, PAAm/AAcNa), polyacrylic add (PAA), guar gum (GG), carboxymethylcellulose (CMC) and sodium salts, as well as hydroxyethylcellulose (HEC). From these tests, PEO proved to be the most effective flow improver, followed closely by PAAm, which is somewhat more stable than PEO in turbulent flow. 

The commercialization of new watei-soluble polymers is most often a slow process. For example, hydroxyethylcellulose (HEC) was envisaged in 1937 by... 

A popular approach to improve ocular drag bioavailability is to incorporate soluble polymers into an aqueous solution to extend the drug residence time in the cul-de-sac. It is reasoned that the solution viscosity would be increased and hence solution drainage would be reduced. The more commonly used viscolyzing agents include PVA and derivatives of cellulose. Cellulosic polymers, such as methylcellulose, hydroxyethylcellulose (HEC), hydroxypropyl-methylcellulose (HPMC) and hydroxypropylcellulose (HPC), are widely used as viscolyzers showing Newtonian properties. They have common properties ... 

Because of low solubility of the compound in pure water, for the oral administration a suspension in an aqueous solution of hydroxyethylcellulose (0.5 %) was used. The solid state physical parameters (particle size, surface area, amorphicity and crystal modification) and the suspension properties (agglomeration tendency, homogenicity and dissolved part of the drug) had to be investigated. For the intravenous administration, an aqueous solution containing saline, DMSO and PEG 400 was used as formulation. 

Water soluble hydroxyethylcelluloses have molar substitutions ranging from 1.5 to 2.5. Hydroxyethylcellulose is used as a thickener for latex paints,... 

Isogai and coworkers [99] recently prepared a series of tri-O-alkylcellulose ethers using a technique that was originally developed for permethylations and involves the use of alkyl halides, powdered sodium hydroxide, and non-aqueous solvents. Water-soluble phosphonomethylcellulose products have been produced by modiflcation of cellulose ethers with chloromethanephos-phonic acid derivatives [87,100]. Low levels of hydrocarbon residues can be incorporated into cellulose ethers, such as hydroxyethylcellulose, to yield high-viscosity, water-soluble products that display non-Newtonian behavior at low shear rates [ 101,102]. Small amounts of 2-(A, yV-diethylamino)ethylcel-lulose can be produced by the Williamson reaction of alkali cellulose with the hydrochloride of 2-chloroethyldiethylamine [103]. 

Chemical modification of hydroxyethylcellulose or hydroxypropylcellulose with long-chain hydrocarbon alkylating reagents, such as C8-C24 epoxides or halides, has been reported to yield novel water-soluble compositions exhibiting enhanced low-shear-rate solution viscosities and polymeric surfactant properties [ 104,105]. Patents have also been issued for water-soluble phosphonomethylcellulose and phosphonomethylhydroxyethylcellulose [106,107]. 

Methyl hydroxyethylcellulose (MHEC] Soluble in water and Gl fluids. Elas similar film forming properties to EIPMC but is less soluble in organic solvents, which limited its popularity when solvent coating was the norm. 

Cellulosics. Cellulosic adhesives are obtained by modification of cellulose [9004-54-6] (qv) which comes from cotton linters and wood pulp. Cellulose can be nitrated to provide cellulose nitrate [9004-70-0], which is soluble in organic solvents. When cellulose nitrate is dissolved in amyl acetate [628-65-7], for example, a general purpose solvent-based adhesive which is both waterproof and flexible is formed. Cellulose esterification leads to materials such as cellulose acetate [9004-55-7], which has been used as a pressure-sensitive adhesive tape backing. Cellulose can also be ethoxylated, providing hydroxyethylcellulose which is useful as a thickening agent for poly(vinyl acetate) emulsion adhesives. Etherification leads to materials such as methylcellulose [9004-67-5] which are soluble in water and can be modified with glyceral [56-81-5] to produce adhesives used as wallpaper paste (see Cellulose esters Cellulose ethers). 

Abstract. The presence of water-soluble polymers affects the microstructure of polymer-modified cement mortar. Such effects are studied by means of SEM investigation. Polyvinyl alcohol-acetate (PVAA), Methylcellulose (MC) and Hydroxyethylcellulose (HEC) are applied in a 1 % polymer-cement ratio. The polymers provide an improved dispersion of the cement particles in the mixing water. The tendency of certain water-soluble polymers to retard the flocculation of the cement particles minimizes the formation of a water-rich layer around the aggregate surfaces. They also provide a more uniform distribution of unhydrated cement particles in the matrix, without significant depletion near aggregate surfaces. Both effects enable to reduce the interfacial transition zone (ITZ). The polymers also provide a more cohesive microstructure, with a reduced amount of microcracks. 

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