Nietionisch

Nietionisch is a term used in some chemical and materials science contexts to denote substances or systems that do not form ions under a defined set of conditions. It serves to distinguish non-ionic behavior from ionic or zwitterionic behavior, particularly in discussions of solutions, polymers, and surface-active agents. The word is a Dutch neologism formed from niet (not) and ionisch (ionic), and it appears mainly in Dutch-language technical writings and in some European glossaries. In many English-language sources, the equivalent concept is described as non-ionic, though nietionisch reflects a direct linguistic derivation.

In practice, nietionisch refers to materials where ionization is negligible: little to no dissociation into ions in the relevant medium, overall electrical neutrality, and interactions governed by van der Waals forces or hydrogen bonding rather than ionic attraction or repulsion. Typical examples discussed under this notion include non-ionic surfactants and certain neutral polymers, as well as solvents or solvent phases where charge carriers are not appreciably generated under the conditions of interest. The term is often used in formulations, coatings, and colloid science to emphasize the absence of ionic species.

Nietionisch is distinct from terms like ionic and zwitterionic and is sometimes contrasted with them in theoretical discussions about conductivity, solubility, and interfacial behavior. It can overlap with discussions of non-polar or weakly polar systems, where ionic processes are suppressed. See also non-ionic, ionic, zwitterion, surfactant, electrolyte.