Wettability group

Similar techniques can also be used to control the wettability of a surface actively (in time scales of the order of seconds), for example, by electrochemically controlling the interconversion of less polar (less wettable) groups in the SAMs to more polar (more wetta-ble) groups (Abbott and Whitesides 1994). 

The lowest wettable surface known = 6 dyne/cm) is a monolayer of perfluoro-launc acid on platinum, whose surface is made up of closely packed CF3 groups [20] Fluonnated graphite, (C2FJ and (CF) , also have surface tensions approachmg 6 dyne/cm [21] Perfluorinated materials, however, are not required tor low surface energies only the outermost surface groups must be perfluorinated [20, 22]... 

Thermal aging is another simple pretreatment process that can effectively improve adhesion properties of polymers. Polyethylene becomes wettable and bondable by exposing to a blast of hot ( 500°C) air [47]. Melt-extruded polyethylene gets oxidized and as a result, carbonyl, carboxyl, and hydroperoxide groups are introduced onto the surface [48]. 

The surface oxide groups on carbon play a major role in its surface properties for example, the wettability in aqueous electrolytes, work function, and pH in water are strongly affected by the presence of surface groups on the carbonaceous material. Typically, the wettability of carbon... 

Roy et al. (R3) define the critical solids holdup as the maximum quantity of solids that can be held in suspension in an agitated liquid. They present measurements of this factor for various values of gas velocity, gas distribution, solid-particle size, liquid surface tension, liquid viscosity, and a solid-liquid wettability parameter, and they propose the following two correlations in terms of dimensionless groups containing these parameters ... 

We examined protein adsorption to SAMs that carried four different functional groups [42] and mixed SAMs with different wettabilities [21], Large amounts of serum proteins adsorbed to all these SAMs, but the different surface functional groups greatly affected cell adhesion behavior (Figs. 2 and 3). Thus, the amount of adsorbed proteins did not correlate with the degree of cell adhesion to SAMs. 

Arima Y, Iwata H (2007) Effect of wettability and surface functional groups on protein adsorption and cell adhesion using well-defined mixed self-assembled monolayers. Biomaterials 28 3074-3082... 

The influence of mixed coupling on the properties of Cl Pigment Yellow 12 has been studied recently [12]. Carboxy- or sulpho- substituted derivatives of acetoacetanilide were evaluated as co-coupling components and analysis revealed that the state of the crystal and the particle size were changed and new diffraction peaks were observed. When these modified pigments were treated with a fatty amine such as stearylamine, the hydrocarbon chains enclosed the anionic groups in the co-coupler so that properties such as flowability, wettability and dispersibility in nonpolar solvents were greatly improved. 

The objective of this work is to determine the surface concentration of the hydroxyl groups of cellulose and PVA films utilizing their chemical modification. We chose these polymers mainly because the hydroxyl group is their sole functional group. Recently we have reported that a cellulose film is more excellent in wettability towards water than PVA, though cellulose is insoluble in water, in contrast to PVA(4). Since only the chemical composition of the surface must be responsible for water... 

The surface wettability of heat-treated wood decreases due to a reduction in the hydroxyl content of the modified wood (Pdtrissans etal., 2003). There is a reduction in the water-sorption capacity, which is related to a reduction in the number of primary sorption sites (OH groups) within the wood cell wall, largely as a result of the removal/degradation of the hemicellulosic component. As remarked upon earlier, hygroscopic properties are strongly influenced by the treatment method employed. Podgorski etal. (2000) heated... 

---