title: Graft copolymers that exhibit temperature-induced phase transitions over a wide range of pH.
abstract: There are many potential applications of 'intelligent' aqueous polymer systems in medicine, biotechnology, industry and in environmental problems. Many of these polymer systems undergo reversible phase transitions--for example, abrupt changes in volume--in response to external stimuli such as temperature, pH or the nature of the solvent. Most of the polymers studied previously are responsive to only one kind of stimulus. But for some applications, independent responsiveness to several factors, such as temperature and pH, may be required. Here we describe a polymer that undergoes marked solubility changes in water in response to temperature and/or pH changes. The polymer is prepared by grafting temperature-sensitive side chains onto a pH-sensitive backbone. We also find that block copolymers, in which the temperature- and pH-sensitive units alternate along the chain, show similar behaviour.
authors.affiliation: Center for Bioengineering, University of Washington, Seattle 98195.
authors.forename: G
authors.initials: G
authors.lastname: Chen
authors.forename: A S
authors.initials: AS
authors.lastname: Hoffman
mesh_terms: D000178:Acrylamides; D000179:Acrylates; D006863:Hydrogen-Ion Concentration; D011108:Polymers; D012995:Solubility; D013696:Temperature
chemical_list: D000178:Acrylamides; D000179:Acrylates; D011108:Polymers; C067295:N-isopropylacrylamide; C036658:acrylic acid