Surface characterization of poly(hydroxyethyl methacrylate) and related polymers. I. Contact angle methods in water

Abstract

SYNOPSISThe characterization of the gel-water interface is considered, particularly with respect to obtaining the interfacial free energy between the gel and water, ysw, utilizing contact angle data. The question of contact-angle-induced deformation of the three-phase region is examined and visual documentation of such deformation is presented. Air in water and octane in water contact-angle data are used to estimate y&, y&, ysv, and ysw for the gel-water interface as a function of bulk water fraction in the gel. It is shown that ysw rr 0 f 5 erg/& when the bulk water fraction is greater than 0.2. All interfacial parameters determined appear to reach a constant value at a bulk'water fraction of about 0.4. These results are for poly(hydroxyethy1 methacrylate), poly(methoxyethy1 methacrylate), poly(dihydroxypropy1 methacrylate), and selected copolymers at 25'C in distilled water.

Elastic deformation of soft membrane with finite thickness induced by a sessile liquid droplet

“…From the figure and table, we found that when x is larger than a certain value such as 8.0, the corresponding function value is almost equal to 1 2 , that is to say, for a given thickness h, the vertical displacement at the upper surface of the membrane can be approximately written as are dimensionless vertical displacement at the surface of a finite-thickness membrane and semi-infinite solid, respectively. The latter part in equations (20), (21) shows the effect of membrane's thickness on the vertical displacement of the membrane. Moreover, it is easily found that the deformation is inversely proportional to Young's modulus of the membrane.…”

“…However, both Lester and Rusanov only considered the effect of a liquid droplet on the deformation of a semiinfinite body rather than a finite-thickness substrate. Besides, Andrade et al studied the contact-angle-induced deformation of gels experimentally and pointed out that the deformation might be relatively large for low-modulus, high-watercontent gels [21]. Some researchers also studied the deformation of a thin solid due to the droplet [22][23][24].…”

Chemical modification of poly(vinyl chloride) resin using poly(ethylene glycol) to improve blood compatibility

“…Values reported are the average of 8-10 measurements on different parts of the film. Surface energy parameters were calculated according to the method of Andrade et al [13].…”

Dynamics of elastocapillary rise

“…Some authors (Lester 1961;Fortes 1984) suggested that the normal component is balanced by a force exerted by the solid, which deforms upon contact. This deformation is generally negligible on a rigid substrate, but can lead to the formation of a ridge (Andrade et al 1979;PericetCamara et al 2008) or wrinkles (Huang et al 2007) on a soft substrate. Motivated by the recent interest in soft materials in engineering, nano-fabrication, and biomechanics, several authors have addressed the question of how slender objects deform under capillary forces (Bico et al 2004;Kim & Mahadevan 2006;Py et al 2007;Pokroy et al 2009), mostly considering equilibrium configurations.…”