Charge and Release: Electrostatics and Thermal Regulation in Smart Materials Design

Charge and Release
Reported by
Sarah Webb

Posted August 04, 2009


Smart materials are polymers and other materials that respond to external stimuli. An April 23, 2009, meeting of the Academy's Soft Materials Discussion Group focused on some basic research that is helping to develop smart materials and on several applications that have already reached consumers.

Eric Dufresne of Yale University described research exploring electrostatic interactions between molecules in different environments. By understanding optical forces and thermal fluctuations his team has made it possible to measure femtoNewton-scale forces between micron-sized plastic particles suspended in oil. The plastic particles can charge spontaneously, and it's possible to observe long-range electrostatic interactions between them. Observations suggest the particles act as micron-sized batteries; the surface charge densities of the particles adjust to maintain fixed electrostatic potentials on the particle surface.

Steven P. Bitler described several successes in integrating temperature-responsive polymers into everyday products. By inserting a variety of co-monomers into side chain crystalline polymers, he and his colleagues can modulate the polymer properties, including melting temperature. Such polymers provide temperature-sensitive materials for smart food packaging, thermosetting mixtures such as epoxy, personal care products, quick release adhesives, agricultural seed coatings, and drug delivery.

Thank you to Professor Qipeng Guo from Deakin University's Centre for Material and Fibre Innovation for use of the title image.

Use the tabs above to find a meeting report and multimedia from this event.


Eric Dufresne

Sainis SK, Merrill JW, Dufresne ER. 2008. Electrostatic interactions of colloidal particles at vanishing ionic strength. Langmuir 24: 13334. (PDF, 133 KB)

Sainis SK, Germain V, Mejean CO, Dufresne ER. 2008. Electrostatic interactions of colloidal particles in nonpolar solvents: role of surface chemistry and charge control agents. Langmuir 24: 1160. (PDF, 128 KB)

Sainis SK, Germain V, Dufresne ER. 2007. Statistics of particle trajectories at short time-intervals reveal fN-scale colloidal forces. Phys. Rev. Lett. 99: 018303. (PDF, 204 KB)

Steven Bitler

Jordan Jr EF, Feldeisen DW, Wrigley AN. 1971. Side chain crystallinity. I. Heats of fusion and melting transitions on selected homopolymers having long side chains. J. Polymer Sci. Part A 9: 1835-1852.

Platé NA, Shibaev VP. 1974. Comb-like polymers: structure and properties. J. Polymer Sci. Macromolecular Rev. 8: 117-253.


Eric Dufresne, PhD

Yale University
e-mail | web site

Eric Dufresne is an assistant professor of mechanical engineering, chemical engineering, and physics at Yale University, where his lab works to understand, control, and exploit the properties of soft materials. After completing his bachelor's degree at Yale College in 1996, Dufresne earned his PhD in physics at the University of Chicago in 2000 in the laboratory of David Grier. In the fall of 2000, he and Grier helped to found Arryx, a company that develops holographic optical tweezers and applies that technology. In 2001–2002, Dufresne worked in the Washington, DC, office of the consulting firm, McKinsey & Co. He completed a postdoctoral fellowship with David Weitz at Harvard University from 2002 to 2004.

Steven P. Bitler, PhD

Landec Corporation
e-mail | web site

Steven Bitler is the Vice President for Corporate Technology at Landec Corporation in Menlo Park, California. He earned his PhD at the University of Southern California and completed postdoctoral research at the University of California, Santa Barbara.

Sarah Webb

Before hanging up her labcoat, Sarah Webb earned a PhD in bioorganic chemistry from Indiana University. Based in Brooklyn, NY, she writes about science, health, and technology for publications including Scientific American, Discover, and Nature Reports Stem Cells.