STRUCTURE IN THIN AND ULTRATHIN SPIN-CAST POLYMER-FILMS

The molecular organization in ultrathin polymer films (thicknesses les s than 1000 angstroms) and thin polymer films (thicknesses between 100 0 and 10,000 angstroms) may differ substantially from that of bulk pol ymers, which can lead to important differences in resulting thermophys ical properties, Such constrained geometry films have been fabricated from amorphous poly(3-methyl-4-hydroxy styrene) (PMHS) and semicrystal line poly(di-n-hexyl silane) (PD6S) by means of spin-casting. The resi dual solvent content is substantially greater in ultrathin PMHS films, which suggests a higher glass transition temperature that results fro m 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 cr ystalline morphology to exist and in which the rate of crystallization is initially slow but increases rapidly as the film approaches 500 an gstroms in thickness.