Wettability, poly

VV -values for bromoform and pyrrole, acidic liquids, against poly(vinyl chloride), an acidic polymer, and dimethyl sulfoxide, a predominantly basic liquid, against polyfmethyl methacrylate), a basic polymer, but large values for the acidic liquids against PMMA and the basic liquid against PVC. 2-Iodoethanol, a bifunctional liquid, showed appreciable -values with both polymers. Despite these results in line with expectations, other results based on wettability measurements are not so clear-cut. For example, Vrbanac [94] found significant apparent acid-base interactions of various aromatic liquids against poly(ethylene), presumably a neutral substrate. 

Hard contact lenses are composed of a polymer that repels water because the constituent repeating units (the monomers that link together to form the polymer) are nonpolar, hydrophobic segments. The first hard contact lens was constructed in 1948 from the monomer known as methyl methacrylate (MMA), yielding the polymer poly(methyl methacrylate) or PMMA. This material offers durability, optical transparency, and acceptable wettability for optimal comfort. Today the rigid lens material of hard contact lenses is often constructed by combining MMA with one or more additional hydrophobic monomers to provide better gas permeability. 

Apart from modifications in the bulk, also surface modification of PHAs has been reported. Poly(3HB-co-3HV) film surfaces have been subjected to plasma treatments, using various (mixtures of) gases, water or allyl alcohol [112-114]. Compared to the non-treated polymer samples, the wettability of the surface modified poly(3HB-co-3HV) was increased significantly [112-114]. This yielded a material with improved biocompatibility, which is imperative in the development of biomedical devices. 

The prototype of the present surface photografting is the surface photoreaction of maleic anhydride(MAH) onto poly(butadiene) film(15). Although fair improvement of surface wettability was achieved, photoaddition of MAH cannot be applied to other polymers having no ethylenic double bonds. The present process is applicable to almost all polymers except for poly(tetrafluoroethy-lene) and its analogues. 

Yakushiji, T, Sakai, K., Kikuchi, A., Aoyagi, T, Sakurai, Y, and Okano, T. Graft architectural effects on thermo-responsive wettability changes of poly(A-isopropylacrylamidej-modified surfaces, Langmuire, 1998, 14, 4657-4662. 

The energy contribution from the MDS study was found mainly from the van der Waals interaction, being less favorable for the poly (ester)s with one Si (la) than with one Ge atom (lb). These results have been in good agreement with the dispersion contribution to the total surface energy which was estimated by wettability measurements [46],... 

The problem here consists in listing the material parameters because, in activated sludge, they fluctuate strongly (much in contrast to ore flotation). Surely, the degree of hydrophobicity (wettability) of the particle surface (contact angle, ) will be of importance. Furthermore, the pH value, the concentration of the flocculant (poly-electrolyte), cF, the portion of solids, [Pg.30]

In a patent dated 1965 Stowe35) laid the basis for the copolymerization of PEO macromonomer with comonomers such as acrylonitrile. It was searched for an increased wettability of polyacrylonitrile films or fibers by a permanent surface modification. ro-Styryl poly(oxyethylene) macromonomers readily copolymerize with acrylonitrile in water emulsions. They can also be copolymerized with styrene-sulfonates in the presence of poly(vinylpyrrolidone). The presence of small amounts of such copolymers in polyacrylonitrile fibers was shown to increase their wettability and their receptivity to dyes and to make them more resistant to electric loading (antistatic fibers). No characterization data on the copolymers formed have been reported. 

The effect of ultraviolet irradiation in air on the wettability of thin films of amorphous polymers has been studied. With poly(vinyl chloride), poly(methyl methacrylate), poly(n-butyl methacrylate), poly (ethylene terephthalate), and polystyrene the changes in contact angles for various liquids with irradiation time are a function of the nature of the polymer. A detailed study of polystyrene by this technique and attenuated total reflectance spectra, both of which are sensitive to changes in the surface layers, indicates that the contact angle method is one of the most sensitive tools for the study of polymer photooxidation in its early stages. The method is useful in following specific processes and in indicating solvents to be used in the separation and isolation of photooxidation products. 

The adhesion and wettability of thin films of poly(n-butyl methacrylate)(PBMA) and (butyl methacrylate/co-acrylic acid)(AA/BMA) cast from various solvents was studied. Most PBMA films showed adhesive failure regardless of the solvent from which they were cast. The AA/BMA films showed better adhesive properties when cast from the hydrogen-bonding solvents t-butanol and p-dioxane. 

The adhesion force of pad particles on the poly-Si wafer surfaces was measured in the KOH solution (pH 11) as a function of polysilicon wettability, which was varied by treating the surface with different concentrations of the oxidizer. As shown in Fig. 16.14, the adhesion force decreases and then levels... 

Hong YK, Kang YJ, Park JG, Han SY, Yun SK, Yoon BU, Hong CK. Effect of poly silicon wettability on organic t5 pe defects in poly CMP. 210th ECS Meeting Cancun Mexico Oct 302005. 

One of the most striking differences between protein-dominated substrates e,g., skin, tissue masses, and blood) and other solid, semi-solid, or liquid surfaces is in their wettability and adhesiveness with other materials. Work on the development of surgical adhesives based upon the poly(a-cyanoacrylates) used successfully in hemostasis for massive... 

The decrease in cos 0 by photoirradiation was also observed for poly( -butyl methacrylate) mixed with 2-hydroxytriphenylmethanol, thoe the increase of 0 was very small ( 4°) even at a content of 45 mol%. In addition, c< 0 after photoirradiation did not depend on the content, but stayed constant within experimental errors up to the content of 45 mol %. The marked difference in wettability behavior between the polymer having the chromophores in the pendant groups and the polymer mixed with the chromophores suggests the difference in the location of the chromophores in the polymers. 

Acrylic acid can be used as comonomer in different copolymers. The most common of these are probably poly(ethylene-co-acrylic acid) (see Section 6.1, Figure 6.1.7), poly(acrylic acid-co-acrylamide), and poly(acrylic acid-co-styrene-co-acrylonitrile) or ASA terpolymer. The acrylic acid in the poly(ethylene-co-acrylic acid) increases the wettability of the polymer. Different salts of poly(acrylic acid-co-acrylamide) are used in the water purification processes as water clarification aid and in drilling fluids. Additional -COOH groups make the polymer even more hydrophilic, and polymers such as poly(acrylic acid-co-maleic acid) are easily water soluble and used as liquid thickeners. 

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