Dynamic contact angle measurement

Dynamic contact angles are the angles which can be measured if the three-phase boundary (liquid/solid/vapor) is in actual motion. A Wilhelmy plate is used in dynamic contact angle measurements, and this method is also called the tensiometric contact angle method. It has been extensively applied to solid-liquid contact angle determinations in recent years. In practice, a solid substrate is cut as a thin rectangular plate, otherwise a solid material is 

1 The sample is above the liquid and the force/length is zeroed. 

2 The sample hits the liquid surface. If the sample has a contact angle 90°, then the liquid 

3 By raising the test liquid level, the sample is immersed, and the buoyant force increases to cause a decrease in the total force on the balance. Advancing contact angle is calculated from this force-immersion depth line. 

---

Takei, Y. G., Aoki, T., Sanui, K., Ogata, N., Sakurai, Y, and Okano, T. Dynamic contact angle measurement of temperature-responsive surfaces properties for poly(Af-isopropylacrylamide) grafted surfaces. Macromolecules, 1994, 27, 6163—6166. 

The Wilhelmy apparatus is suitable for both static and dynamic contact angle measurements. However, it is particularly suited for the measurement of dynamic wetting properties of polymer surfaces, and most Wilhelmy balance is used in the dynamic mode. 

When the solid is removed from the liquid, as in Y-type deposition, the dynamic contact angle measured on the liquid phase decreases steadily with increasing speed. At very low removal speeds, i.e. when 0, the contact angle approaches the static contact angle from below, A4>s, i.e. during removal dynamic contact angles... 

Other techniques, such as atomic force microscopy (AFM), and dynamic contact angle measurement (DCA) have been performed to measure the surface roughness and hydro-philicity of the sample, respectively. 

Contact Angle Measurement. Dynamic contact angle measurement was performed on the dried hydrogels at 25°C by the Wilhelmy plate technique using equipment manufactured by Shimadzu Inc. (Automated System for Dynamic Contact Angle Measurement, ST-IS type) Water used for the measurement was purified by de-ionization after double distillation. Five measurements on different parts of the film were averaged. The movement rate of the water vessel into which the gel specimen was immersed was kept at 0,3 mm sec , ... 

Polymer Surface Dynamics Using Surface-Modified Glasses via Dynamic Contact Angle Measurements... 

For the characterization of wetting properties we employed dynamic contact angle measurements as well as measurements of sliding/roll-off angles using a Data-Physics OCA20 measurement system. 

Figure 8. Typical stages of drop shape development (schematically) during dynamic contact angle measurement cycle (after [6]). The increase or decrease of drop volume is indicated by arrows.

Figure 12. Dynamic contact angle measurement on laser-structured ultra-hydrophobic steel surface (sample A) left advancing contact angle right receding contact angle.

For dynamic contact angle measurement, the test surface was mounted on an Aerotech ALSIOOO linear translation stage capable of moving a specified distance within 1 pm for any velocity and acceleration used in the course of these experiments. A 1.3 mm outer diameter needle was positioned 250 pm above the substrate surface. This needle suspends a liquid droplet the liquid remains attached to the... 

Aqueous SDS solutions/oil systems The interfacial tension of the solutions against oil and the corresponding capillary numbers are summarized in Table 1. Static contact angles and the advancing dynamic contact angles measured in capillaries as a function... 

They used amphiphilic methacrylate polymer with a ternary amino group, poly(A,A-diisopropylaminoethyl methacrylate (DlPAM)-co-n-decyl methacrylate (DMA)) (PDD), composed of 25 unitmol% of DMA in the polymer as a polymeric additive to SPU. The content of the PDD in the SPU was in the range of 1-5 wt%. The surface characteristics of the SPU/PDD polymer alloy were examined by XPS and dynamic contact angle measurements with water. These evaluations revealed that the PDD was located on the surface of the polymer alloy. This induced a more hydrophilic and movable surface compared with untreated SPU. Protein adsorption from human plasma was also reduced on the surface of the SPU/PDD polymer alloy. During the blending process, the solubility of the polymer added to the SPU is important. The solubility parameter of the polymer is one of the factors used to estimate the blending state of both polymers. 

A typical example of the measured weight changes during dynamic contact angle measurements between carbon fibers and water as well as diio-domethane (DIM) is shown in Fig. 19. No buoyancy slope can be observed, even when using more fibers because of the small fiber diameter (around 7 pm) [41]. 

Ram6, E. 1997. The interpretation of dynamic contact angles measured by the Wilhelmy plate method. Journal of Colloid and Interface Science 185 245-251. 

In practical systems such as in spray applications, one has to displace one fluid (air) with another (liquid) as quickly and as efficiently as possible. Dynamic contact angle measurements (associated with moving wetting line) are more relevant in... 

In many experimental situations, a contact angle that changes with time leads inevitably to the movement of the wetting line [29]. The result is a dynamic contact angle. This situation arises from non-equilibrium conditions and should be distinct from contact angle hysteresis. In dynamic contact angle measurements, some movement of the wetting line is unavoidable and this must cause a tempo-... 

TAK 94] Takei Y.G., AoKi T., Sanui K. et al, Dynamic Contact Angle Measurement of Temperature-Responsive Surface Properties for Poly(N-isopropylaciylamide) Grafted Surfaces , Macromolecules, vol. 27, pp. 6163-6166,1994. 

Table 8.1 Surface energy and dynamic contact angle measurements for specified surfaces...

---