Page 109 - Handbook of Surface Improvement and Modification

104 Surface Tension and Wetting

Figure 7.9. (a–f) SEM and TEM images of PS/PANI composite microspheres and PANI hollow microspheres; (g)
and (h) Examples of reversible wettability switching by changing the pH and the applied voltage. [Adapted, by
permission, from Tan, L; Cao, L; Yang, M; Wang, G; Sun, D, Polymer, 52, 4770-6, 2011.]
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response. The combination of hydroxylation degree, wettability, surface charge, and
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energy (polar component) emerged as the key parameters for cell adhesion.
The surface wettability is of importance in the settlement of macrofouling larvae
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such as barnacles, bryozoans and hydroids. Unlike in most studies, the hydrophilic sur-
face of polystyrene-reduced settlement of barnacles by 38% as compared to the surfaces
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of low wettability (hydrophobic PS). It was concluded that wettability might cause a bio-
logical inhibition by interacting with chemoreceptors when the larva is making surface
contact, or the inhibition might be of a physical-chemical nature and thus, surface contact
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is impeded by repulsive chemical forces.
Prevention of Pseudomonas aeruginosa settlement onto soft-contact lenses may pre-
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vent sight-threatening microbial keratitis. Substrate surface wettability is known to mod-
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ulate adhesion of P. aeruginosa. Pluronic F127 and three ethylene oxide-butylene oxide
surfactants were studied with four commercially available silicone-hydrogel contact
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lenses. The bacterial adhesion to all lenses was independent of surface wettability. 16
Although the polymeric surfactants lowered contact angles under leaching conditions and
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increased lens wettability, their use was not preventing antifouling of soft-contact lenses.
Surface tension and wettability improve compatibility, lubrication, and conductivity
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as the selected examples show. Maleic anhydride-grafted polysulfone was used for com-
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patibilization of polysulfone blends with thermotropic liquid crystalline polymer. The