Polymer Inverse Temperature-Dependent Solubility: A Visual Demonstration of the Importance of T Delta S in the Gibbs Equation Academic Article

abstract

• Reversible polymer dehydration and precipitation from water due to the unfavorable entropy of hydration is examined using a melting-point apparatus. The thermoresponsive lower critical solution temperature (LCST) behavior of poly(N-isopropylacrylamide) (PNIPAM) is responsible for these effects. An experiment is described that allows students to test the effects of different salts at various concentrations on PNIPAM's LCST. These studies demonstrate the Hofmeister effect of salts on macromolecule hydration. The use of readily available melting-point equipment and sealed capillary tube samples of aqueous solutions of PNIPAM in various salts provides an economical and simple way to study these phenomena. 2012 American Chemical Society and Division of Chemical Education, Inc.

authors

• Bergbreiter, David

published proceedings

• JOURNAL OF CHEMICAL EDUCATION

author list (cited authors)

• Bergbreiter, D. E., Mijalis, A. J., & Fu, H.

citation count

• 4

complete list of authors

• Bergbreiter, David E||Mijalis, Alexander J||Fu, Hui

publication date

• April 2012

publisher

• American Chemical Society (ACS)  Publisher

published in

• Journal of Chemical Education  Journal

keywords

• Hands-on Learning/manipulatives
• Laboratory Instruction
• Materials Science
• Noncovalent Interactions
• Organic Chemistry
• Polymer Chemistry
• Second-year Undergraduate
• Thermodynamics
• Upper-division Undergraduate

Digital Object Identifier (DOI)

• 10.1021/ed2003669

start page

• 675

end page

• 677

volume

• 89

issue

• 5

URL

• http%3A%2F%2Fdx.doi.org%2F10.1021%2Fed2003669