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2006
Book Article
Titel
Polymeric betaines: Synthesis, characterization, and application
Abstract
This review summarizes mostly the literature data accumulated during the last decade on betaine-type polyampholytes. Synthetic pathways to polybetaines consisting of radical polymerization, the Michael addition reaction, and polymer-analogous transformation are discussed together with methods of controlled polymerization, such as group transfer polymerization, atomic transfer radical polymerization, and reversible addition fragmentation transfer. The role of intra- and interchain associates resulting in insolubility in pure water due to the formation of ionically cross-linked network structures, and solubility in saline water because of the disruption of the ionic networks, are outlined. Attention is also paid to the recent advancement of hydrophobically modified polymeric betaines with emphasis on phospholipid-containing vinyl polymers. Polymer complexes of polybetaines, in particular interpolyelectrolyte, polymer-surfactant, and polymer-metal complexes, are considered in the light of the competition between intra and intermolecular ionic contacts and the cooperative character of interactions. Stimuli-sensitive behavior and morphological changes of polybetaine hydrogels triggered by changes of the pH, ionic strength, water-organic solvent mixture, metal complexation, and DC electric field are discussed with respect to the ionization state of the macromolecules and the thermodynamic quality of solvents, as well as osmotic, chelating, and polarization effects. Some application aspects of polybetaines in medicine, biotechnology, hydrometallurgy, and the oil industry are also discussed.