LEVERAGING ENHANCED SURFACE DYNAMICS TO PREPARE EXTRAORDINARILY STABLE ORGANIC GLASSES
Kenneth L. Kearns* and Mark D. Ediger (Ph.D. advisor)
Department of Chemistry
University of Wisconsin-Madison, Madison, WI 53706
* Currently: Polymers Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
By taking advantage of enhanced dynamics at the surface of amorphous systems, we have shown that physical vapor deposition, when properly controlled, can result in remarkably stable glasses of indomethacin (IMC) and tris-naphthylbenzene (TNB). In a matter of hours, we can prepare glasses that would have taken at least hundreds of years to prepare by isothermal aging. Using DSC and qi-TMDSC, the low enthalpy, high kinetic stability, and distinct packing arrangements of these materials has been studied. Brillouin light scattering showed that the modulus of these deposited glasses is up to 19% greater than for glasses prepared by traditional cooling methods. Nanocalorimetry experiments show that the transformation kinetics of the stable as-deposited glass into the supercooled liquid depends on the sample thickness and is likely an interface initiated process.