Hydrophilic-Hydrophobic Interactions

The alkaline product from the wood ash was a crude solution of sodium and potassium carbonates called "lye". On boiling the vegetable oil with the lye, the soap (sodium and potassium salts of long chained fatty acids) separated from the lye due to the dispersive interactions between the of the fatty acid alkane chains and were thus, called "lyophobic". It follows that "lyophobic", from a physical chemical point of view, would be the same as "hydrophobic", and interactions between hydrophobic and lyophobic materials are dominantly dispersive. The other product of the soap making industry was glycerol which remained in the lye and was consequently, termed "lyophilic". Thus, glycerol mixes with water because of its many hydroxyl groups and is very polar and hence a "hydrophilic" or "lyophilic" substance. 

These points, however, do not address the central question of how organisms deal with a contaminated environment with which they have to interact in order to obtain energy and metabolites. Crucial to these processes are the cellular processes which can modify the ionisation of molecules, their hydrophilic/ hydrophobic properties, and the matrix within which they exist. Many of these changes occur in the alimentary tract but they also occur at the cellular... 

The present author has developed a novel method called ion-association method. This is also a simple and versatile method for the preparation of ion-based organic dye nanoparticles in pure aqueous solution by the ion association approach [23]. It utilizes the control of hydrophilicity/hydrophobicity of the ionic material itself via ion-pair formation for example, addition of a cationic target dye solution into aqueous solution containing a certain kind of hydrophobic anions forms an electrically neutral ion-pair because of the strong electrostatic attraction, followed by aggregation of ion-pair species originated from van der Waals attractive interactions between them to produce nuclei and the subsequent nanoparticles (Fig. 3). In this case, hydrophobic but water-soluble anions, such as tetraphenyl-borate (TPB) or its derivatives (tetrakis(4-fluorophenyl)borate (TFPB), tetrakis [3,5-... 

With the exceptions of water vapour and ice, water in dairy products contains numerous solutes. Thus, the interactions of water with solutes is of great importance. Hydrophilic compounds interact strongly with water by ion-dipole or dipole-dipole interactions while hydrophobic substances interact poorly with water and prefer to interact with each other ( hydro-phobic interaction ). 

Cyclodextrins (CD) can form inclusion complexes with small molecules by hydrophilic-hydrophobic interactions [33-37], Three CDs are readily available - 20, 21, and 22, denoted a, / , and y-CD, respectively. As the number of saccharides in the cyclic increases from 20 to 22, the cavity becomes larger. The hydroxy groups occupy the outside surface, resulting in hydrophilicity and high solubility in polar solvents. Their interiors consist of hydrocarbon units, making the cavity hydro-phobic. Thus when CD and a hydrophobic chain dissolve in a common polar solvent, the chain tends to occupy the cavity of the CD to achieve a lower energy level relative to its state in the polar medium this is hydrophobic-hydrophilic interaction. 

Various polyrotaxanes have been prepared by statistical, hydrogen bonding, metal-ligand complexation, and hydrophilic-hydrophobic interactions. Since no attractive force exists between a linear species and the cyclic components, as ex-... 

These micellar cubic mesophases require large surface curvature and low charge density. Their formation is thus favored by the use of surfactant molecules with large polar head group, and acidic conditions under which the charge density at the silicate/surfactant is always limited. The fact that this phase can be prepared with CTAB when PTES is present, suggests the existence of specific interactions between the phenyl groups and the polar head of the surfactant molecules. It was indeed reported that benzene molecules are preferably located at the hydrophilic-hydrophobic interface [29]. 

The interfacial adsorption theory proposes that the orientation of odorant molecules is dependenl upon their behavior at the hydrophilic-hydrophobic interface, taking into account interaction with the mucus and adjacent olfactory membrane. 

Balazs and Lewandowski (1990) have performed simulations of the adsorption of triblock copolymers onto a planar surface, and examined the conformations of the adsorbed chains. Monte Carlo simulations were performed of the motion of hydrophilic-hydrophobic chains on a cubic lattice. These simulations revealed a complex structure in the interfacial region due to the self-assembly of chains, driven by the solvent-incompatible block, reducing adsorption onto the surface. The influence on the surface coverage of length of the hydrophilic segement, polymer concentration, interaction energy between hydrophilic block and the... 

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