Poly , wettability studies

Results to date of wettability studies on clean, smooth, plasticizer-free, polymeric solids of general interest are summarized in Table IV. Included in this table is the value for poly(vinyl alcohol) (y = 37 dynes per cm.) reported by Ray, Anderson, and Scholz [88] the same investigators also found a range in of 40 to 45 dynes per cm. for a series... 

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 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. 

In many studies of wettability Zisman and coworkers have used the contact angles of a series of n-alkanes as a convenient means for determining for low energy solid surfaces [5,6,13,20]. In Figure 2 are plotted the cos 9 vs. 7lv° curves for the n-aUtanes on PMMA surfaces containing 0.5% additive I and 1.0% additive II. The critical surface tensions with additives I and n were 19 and 20 dynes per cm., respectively, representing a decrease of about 20 dynes per cm. from the value of obtained with the additive-free surface. Since the y values of 19 and 20 dynes per cm. are very close to that of 18 dynes per cm. reported by Fox and Zisman [l3] for the n-alkanes on poly-tetrafluoroethylene surfaces, it is apparent that a number of perfluoro-alkane groups are present in the outermost part of the surface phase with the principal axis of each carbon-carbon chain parallel to the surface. 

Lam, K.H., Schakenraad, J.M., Groen, H., Esselbrugge, H., Dijkstra, PJ., Feijen, J., Nieuwenhuis, P. (1995) The influence of surface morpholog) and wettability on the inflammatory response against poly(Hactic acid) a semiquantitative study with monoclonal andhodies. J. Biomed. Mater Res.,29, 929-942. 

Finally, composition gradients from two different polymer chains have also been used to study wettability effects. A polystyrene poly(2-vinylpyridine) gradient allows a switchable wettability if submitted to a selective solvent treatment. In the selective solvent, one of the two chains collapses and the properties of the surface are determined by mainly the other component. The same effect can be exploited when submitting a polyelectrolyte gradient (poly(tert-butylacrylate) vs. poly(2-vinylpyridine)) to a pH change, Fig. 19. 

S. Bhattachatya, A. Datta, J. M. Berg, and S. Gangopadhyay, "Studies on surface wettability of poly(dimethyl) siloxane (PDMS) and glass under oxygen plasma, treatment and correlation with bond strength," Journal of Microelectromechanicd Systems, vol. 14, pp. 590-597,2005. 

---