Density functional theory. Terahertz spectroscopy. Vibrational spectroscopy.
Binding energy. Crystal lattices. Drug products. Pharmaceutical Preparations. Crystal Growth and Design , 13 7 , In: Crystal Growth and Design , Vol. Crystal Growth and Design. Delaney, Sean P. In: Crystal Growth and Design.
AU - Smith, Tiffany M. Access to Document Link to publication in Scopus. Link to citation list in Scopus. Incorporating this value into the surface energy equation allows for the surface energy to be estimated. The presence of an interface influences generally all thermodynamic parameters of a system. There are two models that are commonly used to demonstrate interfacial phenomena, which includes the Gibbs ideal interface model and the Guggenheim model.
All extensive quantities of the system can be written as a sum of three components: bulk phase a, bulk phase b, and the interface, sigma. While these quantities can vary between each component, the sum within the system remains constant. At the interface, these values may deviate from those present within the bulk phases. The concentration of molecules present at the interface can be defined as:. Spreading Parameter: Surface energy comes into play in wetting phenomena.
To examine this, consider a drop of liquid on a solid substrate. If the surface energy of the substrate changes upon the addition of the drop, the substrate is said to be wetting. The spreading parameter can be used to mathematically determine this:. The Young equation relates the contact angle to interfacial energy:. Wetting of high and low energy substrates: The energy of the bulk component of a solid substrate is determined by the types of interactions that hold the substrate together.
High energy substrates are held together by bonds, while low energy substrates are held together by forces. Covalent, ionic, and metallic bonds are much stronger than forces such as van der Waals and hydrogen bonding. High energy substrates are more easily wet than low energy substrates.
The most commonly used surface modification protocols are plasma activation , wet chemical treatment, including grafting, and thin-film coating. Many techniques can be used to enhance wetting. Surface treatments, such as Corona treatment ,  plasma treatment and acid etching,  can be used to increase the surface energy of the substrate. Additives can also be added to the liquid to decrease its surface energy. This technique is employed often in paint formulations to ensure that they will be evenly spread on a surface.
As a result of the surface tension inherent to liquids, curved surfaces are formed in order to minimize the area. This phenomenon arises from the energetic cost of forming a surface. As such the Gibbs free energy of the system is minimized when the surface is curved. The Kelvin equation is based on thermodynamic principles and is used to describe changes in vapor pressure caused by liquids with curved surfaces. The cause for this change in vapor pressure is the Laplace pressure.
source url The vapor pressure of a drop is higher than that of a planar surface because the increased Laplace pressure causes the molecules to evaporate more easily. Conversely, in liquids surrounding a bubble, the pressure with respect to the inner part of the bubble is reduced, thus making it more difficult for molecules to evaporate.
With the advent of X-ray diffraction and crystal structure determination in researchers in physics and chemistry began investigating the problem of crystal co. [BY] Popular Writer: Crystal Cohesion And Conformational Energies Topics In Current Physics - [PDF]. Crystal Cohesion And Conformational Energies Topics In.
The Kelvin equation can be stated as:. Pigments offer great potential in modifying the application properties of a coating. Due to their fine particle size and inherently high surface energy, they often require a surface treatment in order to enhance their ease of dispersion in a liquid medium. New surfaces are constantly being created as larger pigment particles get broken down into smaller subparticles. These newly formed surfaces consequently contribute to larger surface energies, whereby the resulting particles often become cemented together into aggregates.
Because particles dispersed in liquid media are in constant thermal or Brownian motion, they exhibit a strong affinity for other pigment particles nearby as they move through the medium and collide. The chief purpose of pigment dispersion is to break down aggregates and form stable dispersions of optimally sized pigment particles. This process generally involves three distinct stages: wetting, deaggregation, and stabilization. A surface that is easy to wet is desirable when formulating a coating that requires good adhesion and appearance.
This also minimizes the risks of surface tension related defects, such as crawling, catering, and orange peel. Finally, the particles are subjected to a repulsive force in order to keep them separated from one another and lowers the likelihood of flocculation. Dispersions may become stable through two different phenomena: charge repulsion and steric or entropic repulsion. Alternatively, steric or entropic repulsion is a phenomenon used to describe the repelling effect when adsorbed layers of material e.
Only certain portions i. As the particles approach each other their adsorbed layers become crowded; this provides an effective steric barrier that prevents flocculation. As a result, energy is increased and often gives rise to repulsive forces that aid in keeping the particles separated from each other. From Wikipedia, the free encyclopedia. Woodruff, ed. Reviews of Modern Physics.
Bibcode : RvMP Advances in Chemistry Series. Journal of Applied Polymer Science. Physical Review Letters.
Bibcode : PhRvL.. Analytical and Bioanalytical Chemistry.