Synthesis and characterization of branched and hyperbranched polyetherimides and selective chemistry on the nanolithographically defined silicon(100) surface

Part I of this thesis describes the synthesis and characterization of new hyperbranched derived from AB₂ monomers and new branched copolyetherimides derived from AB and AB₂ monomers where the extent of branching is stoichiometrically controlled. The materials were synthesized using a highly efficient single step process involving a rapid fluoride catalyzed arylation reaction and allowed access to high molecular weight hyperbranched polyetherimides (HBPEI) with varying degrees of branching ranging from 66% to 42%. Initial studies indicate that blending small amounts of the hyperbranched polyetherimide with linear polyimides effectively modifies the surface properties of linear polyimides. The synthesis and characterization of a series of polyetherimide copolymers covering a wide range of branching contents shows that there exists a small window of AB/AB₂ monomer ratios (2.5% to 7.5% AB₂ ) which produce copolymer materials having a combination of the mechanical properties seen for the pure linear polyetherimide polymer, but with the lowered solution viscosities typically seen for highly branched materials.; Part II of this thesis describes studies regarding spatially defined, area selective chemistry on the Si(100)-2 x 1 surface. Using the tip of a scanning tunneling microscope (STM) as a localized electron beam, hydrogen can be site selectively removed from the hydrogen-terminated Si(100)-2 x 1 surface in ultrahigh vacuum (UHV) to expose nanometer sized, highly reactive “templates” of clean Si(100). The inherent reactivity differences between the clean and hydrogen terminated surface allow for the selective reaction of organic olefins such as norbornadiene and metal precursors such as titanium tetrachloride were shown to chemoselectively react with the nanopatterned Si(100) surface. Additional studies of the hydrogen-terminated Si(100) exposed to ambient conditions showed that the UHV prepared hydrogen-terminated silicon surface is stable and that using proper precautions the exposed surface can be reintroduced into UHV without damage or contamination. This will provide new opportunities for ex-situ chemical elaboration of chemically modified nanopatterned areas on the silicon surface.