Dipole interaction bonding

Secondary Bonding. The atoms in a polymer molecule are held together by primary covalent bonds. Linear and branched chains are held together by secondary bonds hydrogen bonds, dipole interactions, and dispersion or van der Waal s forces. By copolymerization with minor amounts of acryhc (CH2=CHCOOH) or methacrylic acid followed by neutralization, ionic bonding can also be introduced between chains. Such polymers are known as ionomers (qv). 

Crosslinked polymer—A three-dimensional polymer created when intermo-lecular forces connect adjacent chains the forces may be hydrogen bonds, dipole interactions, van der Waals forces, or ionic or covalent bonds. 

Pirkle-type phases are amino acid derivatives possessing an aromatic entity which can undergo n-n interactions with the solute. The aromatic entity can be either a n donor or n acceptor. The CSP and the solute form a n donor/acceptor pair. This complex is then stabilized by additional interactions such as hydrogen bonding, dipole interactions, or steric repulsion [8]. The Pirkle-type phases are most commonly used in normal-phase mode in order to enhance the n-n and hydrogen bond interactions. Hexane with an alcoholic modifier, such as isopropanol, is the mobile phase of choice. These phases have... 

Hydrogen bonding dipole interaction between bonded H and the lone-pair of neighboring O, N or S gives structure to liquid water solubilizes alcohols, fatty acids, amines, sugars, and amino acids... 

Many refinements of the Flory-Huggins theory (FH theory) of polymer solutions have been attempted ever since it was proposed in the 1940s. The first one is the detailed study of the mixing entropy and its improvement. The second is to take the semiflexibility of the polymer chains into the theoretical framework. The third is to consolidate its interaction term to accommodate specific interactions such as hydrogen bonds, dipole interaction, hydrophobic force, etc. 

Various types of bonds hold together the atoms in polymeric materials, unlike in metals, for example, where only one type of bond (metaUic) exists. These types are (1) primary covalent, (2) hydrogen bond, (3) dipole interaction, (4) van der Waals, and (5) ionic. Examples of each are shown in Figure 3.1. Hydrogen bonds, dipole interactions, van der Waals bonds, and ionic bonds are known collectively as secondary (or weak) bonds. The distinctions are not always clear-cut, that is, hydrogen bonds may be considered as the extreme of dipole interactions. The secondary bonds are generally weaker bonds and are responsible for many of the bonds between different polymer chains (intermolecular bonds). 

The bond dipole-bond dipole interactions and the weak orbital overlaps between solute and solvent can be treated in the same manner as hydrogen bonds and the free energies of such binding between aromatic hydrocarbons and SO2 have been reported (Berkheimer and Deno, 1960). By treating the dipole interactions in terms of bond dipole interactions, the total dipole-dipole term is eliminated. The dipole-induced dipole term is generally small relative to the other effects (London, 1937). 

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