MORPHOLOGY OF LANGMUIR-BLODGETT-FILMS FROM POLYGLUTAMATE OBSERVED BY ATOMIC-FORCE MICROSCOPY

The mesoscale surface morphology and molecular scale ordering of Langm uir-Blodgett (LB) bilayers of a polyglutamate statistical copolymer su bstituted with octadecyl side chains on 30 % of its repeat units has b een investigated using atomic force microscopy to elucidate those stru ctural features important for their optical properties. Although a vas t majority of all surfaces observed are extremely smooth on the mesosc ale, a variety of interesting morphologies are observed on the remaini ng surface. Bilayers deposited directly on silicon substrates are seen to differ substantially from those deposited on a supporting LB multi layer of either polyglutamate (PG) or cadmium arachidate. Also the abi lity to capture molecular scale images of the surface and the stabilit y of the surface to scan-induced damage depend on the supporting mater ial. Use of a higher force during scanning in a selected sample area p roduces a local scraping of the PG film. By this method, square holes with 1.6-4.0-nm depths and sizes of 30-500 nm can be produced at selec ted sites in the films.