Aug 25, 2009
Researchers finally uncover the structure of polaroid
A better understanding of the history of polaroid could lead to breakthroughs in nanotechnology, now that the detailed crystalline structure of the substance has been determined.
Polaroid is made from a crystalline material called herapathite, which was first discovered in 1852 when tincture of iodine was dropped into urine from a dog that had been fed quinine in the laboratory of toxicologist William Bird Herapath. He realized that the resulting crystals made excellent polarizers, however, it was not until the 1920s that Edwin Land, of Polaroid fame, ground the crystalline material into a fine powder and extruded it into polymers to make polarizing filters. Surprisingly, the structure of herapathite has only now been unravelled, thanks to Bart Kahr and colleagues of the University of Washington, Seattle.
Kahr has also discovered that Bernotar, an analogue of polaroid that was made independently by Ferdinand Bernauer (1892–1945) and marketed by Karl Zeiss, seems to be a single crystalline film of herapathite. This is just the kind of material needed for organic electronics these days, but nobody knows how Bernauer did it.
About the author
Compiled by John Swain, Northeastern University.
B Kahr et al. 2009 Science 324 1407.
Jyllian Kemsley 2009 Chemical and Engineering News June 22 43.