Hydrophilic character

Fig. 28. Traditional duv-resist design using derivatives of polyhydroxystyrene. Monomer (a) contributes hydrophilic character to the polymer, and its acidic phenol group enhances aqueous base solubiUty monomer (b) provides acid-labile pendent groups.

Synthetic fabrics can also be finished to achieve a number of specific characteristics (199). For example, increased electrical conductivity can improve the antistatic character of polyester. Similarly, finishes that improve hydrophilic character also improve properties related to soil release and soil redeposition (199,200). 

The preceding example implied that water solubility is related to polarity, and indeed the equating of hydrophilic character with polarity (and of hydrophobic character with nonpolarity) is often made. Thus, we may add water solubility to the list of pertinent physical (or chemical) properties related to polarity. If a substance is infinitely soluble in water, high polarity is usually inferred. 

The 20 natural amino acids differ from each other by the nature of their sidechains. Differences involve overall size, hydrophobic or hydrophilic character and, perhaps most importantly, ionization state. While the sidechains are normally written in terms of neutral structures, some may also exist in either protonated or deprotonated forms depending on pH. 

Moisture absorption of nylons differs according to the distance between the amide groups. For example, nylon 4 has a higher moisture absorption than most other nylons, and it is approximately similar to that of cotton. This is a result of the higher hydrophilic character of nylon 4. 

If / > 1 the structural change of the reference molecule affords a more lipophilic substance. / < 1 indicates that the hydrophilic character of the reference... 

The same procedure has been employed to increase the hydrophobic character of cellulose, by introducing fluorine-containing groups, e.g., 2,2-difluoroethoxy 2,2,2-trifluoroethoxy and octafluoropentoxy. Incorporation of hydrophobic moieties into cellulose is expected to increase the polymer compatibility with other materials, e.g., synthetic polymers. Note that an important part of incompatibility is due to the highly hydrophilic character of cellulose. Decreasing this character is expected to affect Tg of the derivative, as shown by cellulose propionate/octafluoropentoxy acetate (total DS = 3.0, partial DS in each moiety = 1.5), whose Tg is only 53 °C. The products are more stable than their fluorine-free counterparts, and the terminal CF2 - H group affects Tg much less than OH-substituted trifluoroethoxy celMose derivatives [196,197]. 

The surface of silica is covered by a layer of acidic silanol and siloxane groups. This highly polar and hydrophilic character of the filler surface results in a low compatibihty with the rather apolar polymer. Besides, highly attractive forces between silica particles result in strong agglomeration forces. The formation of a hydrophobic shell around the silica particle by the sUica-sUane reaction prevents the formation of a filler-filler network by reduction of the specific surface energy [3]. 

Hine J, Mookerjee PK. 1975. The intrinsic hydrophilic character of organic compounds. Correlations in terms of structural contributions. J Org Chem 40 292-298. 

In the case of hydroxymethyl ated polybutadiene, a greater decrease in the intrinsic viscosity as compared to the saturated polybutadiene was observed (see Table I). This can be attributed to the greater hydrophilic character of the -OH group on the polymer chains. 

Clay minerals or phyllosilicates are lamellar natural and synthetic materials with high surface area, cation exchange and swelling properties, exfoliation ability, variable surface charge density and hydrophobic/hydrophilic character [85], They are good host structures for intercalation or adsorption of organic molecules and macromolecules, particularly proteins. On the basis of the natural adsorption of proteins by clay minerals and various clay complexes that occurs in soils, many authors have investigated the use of clay and clay-derived materials as matrices for the immobilization of enzymes, either for environmental chemistry purpose or in the chemical and material industries. 

Layered phosphate/phosphonate and phosphonate materials, obtained by substitution of the phosphate moiety by phosphonate groups, display interesting tunable hydrophilic/organophilic properties for adsorption processes. When Candida rugosa lipase (CRL) is simply equilibrated with zirconium phosphate and phosphonate [135,136], immobilization was demonstrated to take place at the surface of the microcrystals. However, because lipase exhibits a strong hydrophobic character, its uptake by zirconium phosphate and phosphonate was much more related to the hydrophobic/hydrophilic character of the supports than to the surface area properties. A higher uptake is observed for zirconium-phenylphosphonate (78 %)... 

Hydrolysis oftricaprylin in trimethylpentane by Fusarium solani pisi recombinant cutinase immobilized on various zeolites (NaA, NaX, NaY, LZY-82, dealuminated Y) was investigated in order to assess the effect of chemical composition (Si/Al ratio), hydrophilic character and acidity on the catalytic activity [221]. The adsorption of... 

The stability of the dispersions upon dilution at 50 °C and zero value of the osmotic second virial coefficient suggests that the surface of the particles at temperatures above the LCST may possess some hydrophilic character the macromolecules self-organise and build up particles with hydrated po-... 

The Hayase procedure [6] discussed in section 10.1.1.2 has also been applied to marine sediments. Sedimentary fulvic acid exhibited increasing hydrophilic character with increasing molecular weight. The method used was effective for hydrophobichydrophilic characterization of humic substances. 

Poly(vinyl alcohol) (PVA) seems to be one of the most efficient polymer matrix for CD-containing membranes owing to its ability to form free-standing films and its hydrophilic character due to the presence of hydroxyl groups. In these membrane materials CDs have been either trapped in PVA [83,84] or covalently linked to the chain [106],... 

Polyvinyl alcohol (PVA), which is a water soluble polyhidroxy polymer, is one of the widely used synthetic polymers for a variety of medical applications [197] because of easy preparation, excellent chemical resistance, and physical properties. [198] But it has poor stability in water because of its highly hydrophilic character. Therefore, to overcome this problem PVA should be insolubilized by copolymerization [43], grafting [199], crosslinking [200], and blending [201], These processes may lead a decrease in the hydrophilic character of PVA. Because of this reason these processes should be carried out in the presence of hydrophilic polymers. Polyfyinyl pyrrolidone), PVP, is one of the hydrophilic, biocompatible polymer and it is used in many biomedical applications [202] and separation processes to increase the hydrophilic character of the blended polymeric materials [203,204], An important factor in the development of new materials based on polymeric blends is the miscibility between the polymers in the mixture, because the degree of miscibility is directly related to the final properties of polymeric blends [205],... 

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