C. W. Frank, V. Rao, ^* M. M. Despotopoulou, R. F. W. Pease, W. D. Hinsberg, R. D. Miller, J. F. Rabolt

The molecular organization in ultrathin polymer films (thicknesses less than 1000 angstroms) and thin polymer films (thicknesses between 1000 and 10,000 angstroms) may differ substantially from that of bulk polymers, which can lead to important differences in resulting thermophysical properties. Such constrained geometry films have been fabricated from amorphous poly(3-methyl-4-hydroxy styrene) (PMHS) and semicrystalline poly(di-n-hexyl silane) (PD6S) by means of spin-casting. The residual solvent content is substantially greater in ultrathin PMHS films, which suggests a higher glass transition temperature that results from a stronger hydrogen-bonded network as compared with that in thicker films. Crystallization of PD6S is substantially hindered in ultrathin films, in which a critical thickness of 150 angstroms is needed for crystalline morphology to exist and in which the rate of crystallization is initially slow but increases rapidly as the film approaches 500 angstroms in thickness.

C. W. Frank, V. Rao, and M. M. Despotopoulou are in the Department of Chemical Engineering, Stanford University, Stanford, CA 94305-5025, USA. R. F. W. Pease is in the Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA. W. D. Hinsberg, R. D. Miller, and J. F. Rabolt are at the IBM Almaden Research Center, IBM Research Division, 650 Harry Road, San Jose, CA 95120-6099, USA.
^*   Present address: Intel Corporation, 2200 Mission College Boulevard, Santa Clara, CA 95052, USA.

   Present address: Elf Atochem N.A., 900 First Avenue, Post Office Box 61536, King of Prussia, PA 19406, USA.

   Present address: University of Delaware, Materials Science Program, Spencer Laboratory, Newark, DE 19716, USA.