title: Thermally programmable pH buffers.
abstract: Many reactions in both chemistry and biology rely on the ability to precisely control and fix the solution concentrations of either protons or hydroxide ions. In this report, we describe the behavior of thermally programmable pH buffer systems based on the copolymerization of varying amounts of acrylic acid (AA) groups into N-isopropylacrylamide polymers. Because the copolymers undergo phase transitions upon heating and cooling, the local environment around the AA groups can be reversibly switched between hydrophobic and hydrophilic states affecting the ionization behavior of the acids. Results show that moderate temperature variations can be used to change the solution pH by two units. However, results also indicate that the nature of the transition and its impact on the pH values are highly dependent on the AA content and the degree of neutralization.
authors.affiliation: Electronic, Optical, and Nanostructures, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA. dgough@sandia.gov
authors.forename: Dara
authors.initials: D
authors.lastname: Van Gough
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Bunker
authors.forename: Mark E
authors.initials: ME
authors.lastname: Roberts
authors.forename: Dale L
authors.initials: DL
authors.lastname: Huber
authors.forename: Holly F
authors.initials: HF
authors.lastname: Zarick
authors.forename: Mariah J
authors.initials: MJ
authors.lastname: Austin
authors.forename: Jill S
authors.initials: JS
authors.lastname: Wheeler
authors.forename: Diana
authors.initials: D
authors.lastname: Moore
authors.forename: Erik D
authors.initials: ED
authors.lastname: Spoerke
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000179:Acrylates / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D044367:Phase Transition
chemical_list: D000178:Acrylamides; D000179:Acrylates; C067295:N-isopropylacrylamide; C036658:acrylic acid