Contact Angle

Various Applications of Contact Angle Measurement

Where contact angle and surface tension measurements will play the role is compiled in the following fields:

Pharmacy:
Controlled drug release, Wettability and dissolving behavior of pharmaceutical powders, tablets and capsules of various body liquids.

Printing industry:
Wettability processes are of major importance for the offset printing process. All materials involved in the process, such as paper, metal surfaces, and rubber surfaces must have a certain degree of surface tension to result in optimum printing quality. This value depends on the surface tension of printing ink and the dampening solution - respectively.

Semiconductor:
The cleanness and the surface chemical composition on pure semiconductor surfaces and treated surfaces such as nitrides or oxides are correlated to the surface energy of these surfaces, Therefore, the measurement of contact angles is a simple and fast method providing quality control in this field.

Cosmetics:
The contact angle is an important parameter for the cleaning process of shampoos and for the effectiveness of cleaning solutions.  Surface tension  is a parameter for the effectiveness of surfactant solutions. Furthermore,  it is necessary for the development of time and temperature-stable emulsions for various cosmetic products. For example: Titanium Dioxide is used as a sun blocker in sun tan creams. The development of a stable, ultra-fine dispersion of Titanium Dioxide in the sun tan emulsion can be simplified by measuring the surface free energy of the particles to be suspended and the surface tension of the liquid carrier.

Biology:
Wetting of plant surfaces by pesticides and fungicides is very important in determining the effectiveness of the pesticide and fungicide formulations.  Interaction of plant leaf and acid rain is important to know for protecting valuable corps.  Critical surface tension of cell surfaces and bacteria to implants or drug surfaces needed to be identified for curing disease or for an artificial organ implantation.

Lacquers and paints:
Measurement of hydrophobicity of lacquer surfaces, especially for the automobile body coating. Development of stable emulsions for paint’s storage shelf life also involve the interfacial tension between the particle and carrier in the paint formulation. Measurement of interaction/adhesion between paint and substrate surfaces (paper, metal, wood, plastics) is critical in the coating processes, especially for the change from solvent-based paints and lacquers to water-based systems, which usually causes a lot of problems for the coating processes.

Preservation of buildings:
Historical buildings have to be protected and preserved against pollution such as acid rain. Their surfaces have to be impregnated by silicide acid or synthetic materials.

Environment:
Sands polluted by oil can be cleaned by treatment with surfactant solutions.  The progress of the cleaning process can easily be controlled by contact angle measurements on the treated and pretreated samples.

Medical field:
Air-tightness of glass vessels containing medicinal fluid. The tightness of rubber sealing caps on glass surfaces can be predicated by surface free energy measurements. Artificial bones and artificial organs have to have a certain surface free energy to be accepted by the human body. Tubes transporting body fluids have to avoid the buildup of agglomerates. The same is the prerequisite for biomembranes.

Optics:
The wettability of contact lenses as well as the interaction and the effectiveness of cleaning solution formulation for contact lenses can be examined by contact angle measurement.

Dental materials:
The contact angle of saliva on tooth surfaces depends on the materials used in the cleaning process. Artificial material must have a certain surface tension and polarity in order to avoid deposition of bacteria and in case of transplants to ensure good adhesion between tooth and embodiment.

Paper Industry:
Like the printing industry the paper industry is involved in wetting problems. According to its use the paper has to be strongly or weakly hydrophobic or hydrophilic. A beaker made of paper must have a different surface energy than a sheet of newspaper. A juice container must have different surface energies on the outside (printability) than on the inside (liquid-resistant and microbiologically inert).

Polymers:
The interfacial tension and surface free energy of polymers and polymer blend can easily be controlled by surface tension measurement. The interfacial tension between various polymers in a polymer blend or between carbon fibers and surrounding polymer in fiber reinforced material is an important parameter for the stability of the materials.

Synthetic foils:
Corresponding to the production process and the surface treatment (chemical, plasma, and flame treatments) the composition of foils and their surface characteristics can be varied remarkably. Very often the foils have to be printable.

Textiles:
The wettability of single fiber as well as the wettability of fabrics can be determined using tensiometer and contact angle meter. Synthetic fibers are usually coated with hydrophobic materials. The degree of hydrophobicity as well as the homogeneity of the coating can be checked through contact angle measurement.

Adhesives:
The adhesion between different components of composite structures, between different materials like glass and metal, leather and fabrics, wood and paper, can be determined by contact angle measurement. Today, a wide variety of material combinations which have been connected in the past by soldering, welding and means of mechanical connection are more easily and durably connected by adhesives. The work of adhesion of two surfaces connected with adhesives, the wetting of adhesives on the substrate can be determined by contact angle measurement.

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