Hydrophilic surface modifying

Abu Tarboush, B. J., Rana, D., Matsuura, T, Arafat, H. A., and Narbaitz, R. M. 2008. Preparation of thin film composite polyamide membranes for desalination using novel hydrophilic surface modifying macromolecules. Journal of Membrane Science 325 166-175. 

Rana D, Matsuura T, Narbaitz RM, Feng C. Development and characterization of novel hydrophilic surface modifying macromolecule for polymeric membranes. J. Membr. Sci. 2005 249 103. 

Hauck, H. E., Mack, M., Reuke, S., and Herbert, H. (1989). Hydrophilic surface modified HPTLC precoated layers in pesticide analysis. J. Planar Chromatogr.—Mod. TLC 2 268-275. 

B.J. Abu Tarboush, D. Rana, T. Matsuura, H.A. Arafat, R.M. Narbaitz, Fbeparation of thin-fibn-composite polyamide membranes for desalination using novel hydrophilic surface modifying macromolecules, J Memb Sci, 325 (2008) 166-175. 

Clearly, it is important that there be a large contact angle at the solid particle-solution-air interface. Some minerals, such as graphite and sulfur, are naturally hydrophobic, but even with these it has been advantageous to add materials to the system that will adsorb to give a hydrophobic film on the solid surface. (Effects can be complicated—sulfur notability oscillates with the number of preadsoibed monolayers of hydrocarbons such as n-heptane [76].) The use of surface modifiers or collectors is, of course, essential in the case of naturally hydrophilic minerals such as silica. 

Materials that typify thermoresponsive behavior are polyethylene—poly (ethylene glycol) copolymers that are used to functionalize the surfaces of polyethylene films (smart surfaces) (20). When the copolymer is immersed in water, the poly(ethylene glycol) functionaUties at the surfaces have solvation behavior similar to poly(ethylene glycol) itself. The abiUty to design a smart surface in these cases is based on the observed behavior of inverse temperature-dependent solubiUty of poly(alkene oxide)s in water. The behavior is used to produce surface-modified polymers that reversibly change their hydrophilicity and solvation with changes in temperatures. Similar behaviors have been observed as a function of changes in pH (21—24). 

Most molded plastics have a very smooth, hydrophobic surface that must be modified. Chemical etchants are used to oxidize and roughen the surface. The resultant hydrophilic surface promotes good metal-to-plastic adhesion. The etchant is usually a solution of chromic acid and sulfuric acid pure chromic acid can also be used. 

The Jordi glucose-DVB column is a highly polar GPC column used for separating polar compounds. Modified glucose units are bonded to the DVB backbone to yield a hydrophilic surface (Fig. 13.16). 

Membranes UF membranes consist primarily of polymeric structures (polyethersulfone, regenerated cellulose, polysulfone, polyamide, polyacrylonitrile, or various fluoropolymers) formed by immersion casting on a web or as a composite on a MF membrane. Hydrophobic polymers are surface-modified to render them hydrophilic and thereby reduce fouling, reduce product losses, and increase flux [Cabasso in Vltrafiltration Membranes and Applications, Cooper (ed.). Plenum Press, New York, 1980]. Some inorganic UF membranes (alumina, glass, zirconia) are available but only find use in corrosive applications due to their high cost. 

The low temperature ene reactions of 4-substituted-l,2,4-triazoline-3,5-diones (RTD) were used to modify polydiene surfaces. Hydrophilic surfaces (contact angles with water of 30-50°) were obtained on polybutadiene, poly-isoprene and styrene-butadiene copolymers by first treating the polymer at room temperature with RTD (R=Ph,... 

The use of lightly crosslinked polymers did result in hydrophilic surfaces (contact angle 50°, c-PI, 0.2 M PhTD). However, the surfaces displayed severe cracking after 5 days. Although qualitatively they appeared to remain hydrophilic, reliable contact angle measurements on these surfaces were impossible. Also, the use of a styrene-butadiene-styrene triblock copolymer thermoplastic elastomer did not show improved permanence of the hydrophilicity over other polydienes treated with PhTD. The block copolymer film was cast from toluene, and transmission electron microscopy showed that the continuous phase was the polybutadiene portion of the copolymer. Both polystyrene and polybutadiene domains are present at the surface. This would probably limit the maximum hydrophilicity obtainable since the RTD reagents are not expected to modify the polystyrene domains. 

Perhaps a better design for a bis-hydrazide compound to modify carboxylate particles would include a short PEG spacer arm between the two hydrazide groups. This type of linker would result in a hydrophilic surface due to the presence of the PEG spacers, while providing the terminal hydrazide functionality necessary for coupling to carbonyl compounds. Unfortunately, this type of compound is not currently available, so the aliphatic bis-hydrazides are the only choice. 

Fluorescent silica nanoparticles, called FloDots, were created by Yao et al. (2006) by two synthetic routes. Hydrophilic particles were produced using a reverse micro-emulsion process, wherein detergent micelles formed in a water-in-oil system form discrete nanodroplets in which the silica particles are formed. The addition of water-soluble fluorescent dyes resulted in the entrapment of dye molecules in the silica nanoparticle. In an alternative method, dye molecules were entrapped in silica using the Stober process, which typically results in hydrophobic particles. Either process resulted in luminescent particles that then can be surface modified with... 

Pristine CNTs are hydrophobic and cause a lack of solubility in biological aqueous fluids such as blood. The poor solubility of CNTs in blood stream poses a major challenge to in vivo studies making behavior of CNTs difficult to predict and control (Kam et al., 2005 Zheng et al., 2003a, b). Therefore, modification of CNT surface to introduce hydrophilic, functional groups has been utilized in pharmaceutical applications (Lacerda et al., 2006). However, insufficient in vivo evaluation of both pristine and surface-modified CNTs has been performed to answer essential questions on CNT toxicology. Additional in vivo studies also required to devise the best method of administration, means of uptake, metabolism, and elimination of CNTs. The in vivo studies on CNTs performed to date are presented in Table 12.2. 

For the SEC analysis of polyelectrolytes, it is best to use a hydrophilic, polymeric packing or a surface-modified silica packing in which most of the silanols are derivatized. Another approach for the analysis of cationic polyelectrolytes is to use packings derivatized with cationic functional groups ( ). This is the basis of a commercially available SEC packing which is chemically bonded with polyethylenimine (W). 

Dash, P.R., Read, M.L., Fisher, K.D., et al. (2000). Decreased binding to proteins and cells of polymeric gene delivery vectors surface modified with a multivalent hydrophilic polymer and retargeting through attachment of transferrin. J. Biol. Chem., 275, 3793-3802. 

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