STABILITY AND MODIFICATION OF POLYGLUTAMATE LANGMUIR-BLODGETT BILAYERFILMS

Langmuir-Blodgett bilayers of a polyglutamate (PG) statistical copolym er have been investigated using atomic force microscopy (AFM) and X-ra y reflectivity. PG ordered bilayer films on silicon surfaces possess a n 'expanded' thickness of 4.12 +/- 0.05 nm and an average roughness of 0.7 +/- 0.2 nm. Possibilities for surface modification by the AFM tip were explored. Formation of an 'abrasion'' surface morphology was rel ated to a stick-slip mode of the AFM tip movement. Using the AFM tip, several surface modifications were investigated: fabrication of large (several hundreds of nanometers) and small (several nanometers) holes; ''writing'' of grooves of predictable geometry; fabrication of holes of single layer and bilayer depth; cleaning of the surface and fabrica tion of holes inside this new area. The anisotropic mechanical propert ies of the PG bilayer were probed and attributed to orientation of the PG backbones along the dipping direction. The dynamic behavior of the surface changes were observed as well.