Poly-anionic cellulose

However, according to Park and Robinson [193], poly anions are better than polycations in terms of binding and potential toxicity. In general, both anionic and cationic charged polymers demonstrate better mucoadhesive properties than nonionic polymer, such as cellulose derivates or PVA [194,195],... 

Besides these chemically bonded residues, it is possible to form stationary phases for ion-exchange chromatography based on cellulose by impregnation. Examples of this are the polyethylene inline (PEI) and the polyphosphate (Poly-P) celluloses. The cellulose exchangers discussed here have to be distinguished based on their use for an anion- or cation-exchange mechanism. Suitable for the... 

Poly(vinyl acetate) emulsions can be made with a surfactant alone or with a protective coUoid alone, but the usual practice is to use a combination of the two. Normally, up to 3 wt % stabilizers may be included in the recipe, but when water sensitivity or tack of the wet film is desired, as in some adhesives, more may be included. The most commonly used surfactants are the anionic sulfates and sulfonates, but cationic emulsifiers and nonionics are also suitable. Indeed, some emulsion compounding formulas require the use of cationic or nonionic surfactants for stable formulations. The most commonly used protective coUoids are poly(vinyl alcohol) and hydroxyethyl cellulose, but there are many others, natural and synthetic, which are usable if not preferable for a given appHcation. 

Synthetic examples include the poly(meth)acrylates used as flocculating agents for water purification. Biological examples are the proteins, nucleic acids, and pectins. Chemically modified biopolymers of this class are carboxymethyl cellulose and the lignin sulfonates. Polyelectrolytes with cationic and anionic substituents in the same macromolecule are called polyampholytes. 

An interesting feature of current commercial products is that the polymer vehicles available for formulation have been limited to nonionic and anionic materials. The delivery vehicles available included off-the-shelf polymers such as carboxymethylcellulose, soluble starch, hydroxyethyl-cellulose, polyvinyl alcohol, poly(acrylic acid), and polyvinylpyrrolidone, or mixtures thereof. The choice of available polymeric delivery system primarily depends on component compatibility, aesthetics, and efficacy. However, by reliance upon available (off-the-shelf) systems, limitations on bioadhesion, drug bioavailability, contraceptive efficacy, and end-use characteristics has been limited. 

Cellulose disintegrants have been studied as insoluble matrices for sustained release tablets. Anionically charged carboxymethyl cellulose (sodium salt) was found to be inferior to methyl cellulose and poly(vinyl pyrollidone) as a binding agent for oxyphenbutazone tablets [291], However sodium carboxymethyl cellulose has found application as a dispersing agent for ibuprofen microspheres... 

In a related application, polyelectrolyte microgels based on crosslinked cationic poly(allyl amine) and anionic polyfmethacrylic acid-co-epoxypropyl methacrylate) were studied by potentiometry, conductometry and turbidimetry [349]. In their neutralized (salt) form, the microgels fully complexed with linear polyelectrolytes (poly(acrylic acid), poly(acrylic acid-co-acrylamide), and polystyrene sulfonate)) as if the gels were themselves linear. However, if an acid/base reaction occurs between the linear polymers and the gels, it appears that only the surfaces of the gels form complexes. Previous work has addressed the fundamental characteristics of these complexes [350, 351] and has shown preferential complexation of cationic polyelectrolytes with crosslinked car-boxymethyl cellulose versus linear CMC [350], The departure from the 1 1 stoichiometry with the non-neutralized microgels may be due to the collapsed nature of these networks which prevents penetration of water soluble polyelectrolyte. 

The hemocompatibility of poly(amido-amine) polyelectrolyte complexes was recently studied by Xi, Zhang and coworkers [499, 500]. The poly(amido-amine) was based on piperazine and methylene bisacrylamide, and the polyelectrolyte complexes were obtained from the reaction of poly(amido-amine) with alginic acid, carboxymethyl cellulose or poly(methacrylic acid). Complexes of polyamido-amine and alginic acid with a 1 2 ratio gave the best hemocompatibility. Finally, the blood compatibility of polyelectrolyte complexes based on anionic and cationic cellulose derivatives were studied by Ito et al. [338], In vivo, good blood compatibility of complexes formed from quaternary hy-droxyethyl cellulose reacted with carboxymethyl cellulose and cellulose sulfate was observed. 

Figure 9.9 Comparison of separation of ethanol/water mixtures by distillation and by three pervaporation membranes cellulose triacetate (CTA), an anionic polyelectrolyte membrane, and GFT s poly(vinyl alcohol) (PVA) membrane [40]...

Fig. 18 a, b. Typical permeabilities of various hydrogels to water and various solutes (a) Water permeability at pressures less than 7 x 107 dyne/cm2 531 (1) = polyelectrolyte complex of poly-(sodium styrenesulfonate) (NaSS)-poly(4-vinylbenzyltrimethylammonium chloride) (PVBMA), (2) = crosslinked hydrogel of poly(2-hydroxyethyl methacrylate), (3) - cellulose (b) Dialytic permeability of a polyelectrolyte complex composed of NaSS-PVBMA to solutes with various molecular weights541 (1) Water, (2) neutral polyelectrolyte complex (water content = 70%), (3) anionic polyelectrolyte complex (water content = 61%), (4) cellophane and cuprophane (water content = 57%)... 

Anionic copolymers consisting of acrylamide and styrene sulfonic acid sodium were prepared by Harrington [1] and used as drainage aids for cellulosic fiber compositions. Doherty [2] anionicaUy prepared high molecular weight poly (acrylamide-co-styrene sulfonic acid sodium), which was also effective as a drainage aid. 

Depending on the ionic charge(s) of the solutes to be separated, anion or cation exchange stationary phases must be used. Common ion exchange support materials include silica, poly(styrene-divinylbenzene), and cellulose. Common anion exchange groups anchored to these supports include 1°, 2°, 3°, and 4"" amines. 

Many types of superabsorbents have been prepared from various materials, by various methods, and in different shapes. They are modified natural hydrophilic polymers such as starch, cellulose, alginic acids, etc. and synthetic hydrophilic polymers such as poly (acrylic acid) and poly(sodium acrylate). Most of them have anionic moieties such as poly(sodium acrylate) and poly(vinyl sulfonate). Now, many types of superabsorbents having not only anionic groups but also cationic groups such as ammonium groups, phospho-nium groups, or betaine have been prepared from both... 

Poly(amino acids)2892 and polypeptides2893 can also be grafted onto starch. Starch was first alkylated in the presence of lithium naphthalene, and then the alkoxy derivatives were reacted with /V-carboxy anhydrides. Poly(amide amines) were produced by reacting amines with dioic acids on starch and then crosslinking with epichlorohydrin or 1,2-dichloroethane 2894 Grafting of starch with a synthetic polymer chain, for instance, polystyryl carboxylate anions prepared by an anionic polymerization, can be carried out on a blend of starch and cellulose functionalized by sulfonation, mesylation, or tosylation. In this manner, cellulose-starch graft copolymers were prepared.2895... 

Plant polyphenols Weakly and medium basic anion exchanger celluloses and poly-dextran Nagels et al. [416]... 

Enzyme activity loss because of non-productive adsorption on lignin surface was identified as one of the important factors to decrease enzyme effectiveness, and the effect of surfactants and non-catalytic protein on the enzymatic hydrolysis has been extensively studied to increase the enzymatic hydrolysis of cellulose into fermentable sugars [7, 9 19]. The reported study showed that the non-ionic surfactant poly(oxyethylene)2o-sorbitan-monooleate (Tween 80) enhanced the enzymatic hydrolysis rate and extent of newspaper cellulose by 33 and 14%, respectively [20]. It was also found that 30% more FPU cellulase activity remained in solution, and about three times more recoverable FPU activity could be recycled with the presence of Tween 80. Tween 80 enhanced enzymatic hydrolysis yields for steam-exploded poplar wood by 20% in the simultaneous saccharification and fermentation (SSF) process [21]. Helle et al. [22] reported that hydrolysis yield increased by as much as a factor of 7, whereas enzyme adsorption on cellulose decreased because of the addition of Tween 80. With the presence of poly(oxyethylene)2o-sorbitan-monolaurate (Tween 20) and Tween 80, the conversions of cellulose and xylan in lime-pretreated com stover were increased by 42 and 40%, respectively [23]. Wu and Ju [24] showed that the addition of Tween 20 or Tween 80 to waste newsprint could increase cellulose conversion by about 50% with the saving of cellulase loading of 80%. With the addition of non-ionic, anionic, and cationic surfactants to the hydrolysis of cellulose (Avicel, tissue paper, and reclaimed paper), Ooshima et al. [25] subsequently found that Tween 20 was the most effective for the enhancement of cellulose conversion, and anionic surfactants did not have any effect on cellulose hydrolysis. With the addition of Tween 20 in the SSF process for... 

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