Polyacrylamide, wettability

In the work of Uchida et al., using the mutual (simultaneous) irradiation method in the absence of a photosensitizer, polyacrylamide has been grafted onto the surface of a poly(ethylene terephthalate) (PET) film so as to enhance the low water wettability of PET [85], The PET film immersed in a 10wt% deaerated solution of acrylamide in water has turned out to be very hydrophilic upon UV irradiation. A pretreatment with benzyl alcohol was carried out to increase the monomer diffusion into the PET matrix, also increasing the grafting efficiency. 

The dynamic adsorption of different polyacrylamides in unconsolidated porous media is discussed. The effect of average molecular mass, degree of hydrolysis, and concentration of polymers, quality and quantity of foreign electrolytes, wettability, chemical composition, and pore structure of porous media on adsorbed amount was studied. The influence of alcohol, surface active agents and alkaline materials is given for practical application of micellar-polymer, caustic-polymer methods. 

Effect of wettability Until now little has been said about the dependence of the adsorption of polyacrylamides on the wettability. Smith (9) has found that the wetting character and the presence of oil do not effect the chemisorption of the polymers. 

As a final result, it has been proven that the adsorption of polyacrylamides on reservoir rocks depends to a great extent on the wettability. In all probability no difference occurs whether the intermediate or oil-wet character of the rock surface is a result of adsorbed monolayer or thick oil film. A certain parallelism can be observed between the adsorption of polyacrylamides and methylene blue on a rock surface. By this far-reaching analogy a new methodological possiblity for semi-quantitative determination of the wetting character in reservoir rock is afforded, using the polymer adsorption (29) similar to the dye adsorption method of Holbrook and Bernard (28). 

The adsorption of the different polyacrylamides depends to a great extent on the wettability. On an oil-wet surface the sorption of the polymers is zero. 

Lim et al. [24] observed that hydrophilic polyacrylamide (PAM) nanofibers effectively wrapped the hydrophilic silica colloids, while hydrophobic polyacrylonitrile (PAN) nanofibers embedded large amounts of hydrophobic silica colloids. Moreover, the addition of a small amount of hexanol to the PEO solution successfully confined all silica colloids inside PEO fibers. Hexanol acted as a surfactant, decreasing the interfacial tension between the silica colloids and PEO (Fig. 16.4). Based on the observations, it was postulated that encapsulation of silica colloids was mainly governed by the wettability of the polymers on the particles. 

This paper presents photografting as a surface modification method to provide permanent wettability improvement to deep-groove polypropylene (PP) fibers. We also describe approaches to evaluate the wettability of these fibers and the wicking performance of fiber bundles when polyacrylamide (PAAm) was grafted onto the fibers. In this study, the concentration of the monomer and the UV-exposure time were altered to examine the effects of those variables on fiber hydrophilicity. Results showed lower water contact angle and improved wicking capacity upon modification with PAAm. 

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