Chemical bonds in the context of "London dispersion force"

In chemistry, polyvalency (or polyvalence, multivalency) is the property of molecules and larger species, such as antibodies, medical drugs, and even nanoparticles surface-functionalized with ligands, like spherical nucleic acids, that exhibit more than one supramolecular interaction. For the number of chemical bonds of atoms, the term "valence" is used (Fig. 1). For both atoms and larger species, the number of bonds may be specified: divalent species can form two bonds; a trivalent species can form three bonds; and so on.

Species that have polyvalency usually show enhanced or cooperative binding compared to their monovalent counterparts. Nanoparticles with multiple nucleic acid strands on their surfaces (e.g., DNA) can form multiple bonds with one another by DNA hybridization to form hierarchical assemblies, some of which are highly crystalline in nature.

Aramid, or aromatic polyamide fibers are a class of strong, heat-resistant, synthetic fibers, commonly used in aerospace and military applications - e.g., ballistic-rated body armor fabric and ballistic composites, marine cordage and hull reinforcement - as a substitute for asbestos, and in lightweight consumer items, such as phone cases and tennis rackets.

Individual amide molecules forming the aramid chain polymerise in the direction of the fiber axis, lending greater structural integrity to the resulting fiber. This is due to the higher proportion of chemical bonds which contribute to the physical strength and thermal resistance (melting point >500 °C (932 °F)) versus other synthetic fibres, such as nylon.