Search

Dendrimer monolayers have been designed for use as positive resists for scanning probe lithography (SPL). Several new amphiphilic poly(benzyl ether) dendrimers with carboxylic acids at either the focal point or the “periphery” have been prepared. These can form ionically bound dendrimer monolayers that may serve as either positive or negative tone resists for SPL. The amphiphilic dendrimers self-assemble onto (3-aminopropyl)silanized Si(100) wafer surfaces to afford ultrathin films. The dendrimer monolayers were characterized by AFM, ellipsometry, and contact angle goniometry. Patterning a singly charged dendrimer monolayer results in the formation of positive tone holes ∼35 nm in width. Similarly, patterning a multiply charged dendrimer monolayer in a direct-write manner with the scanning probe microscope results in the formation of negative tone oxide features ∼80 nm in width.

Poly(amidoamine) (PAMAM) dendrimers, generations 1−6, were peripherally modified with cationically substituted naphthalene diimide groups. Several monomeric diimides were also prepared as models. The structure and loading of the dendrimers were determined by vis, IR, and NMR spectroscopies, elemental analysis, and coulometric analysis. In general it was possible to obtain loadings greater than 70% even from generation 6 dendrimer where there are 192 amine groups to be substituted. These polymers and monomers were reduced using sodium dithionite or electrochemically with one electron per imide group converting each imide into its anion radical. Near-infrared (NIR) spectroscopy showed that in D2O or formamide solutions the anion radicals aggregated into π-dimers and π-stacks. Cyclic voltammograms are interpreted in terms of anion radical aggregation and precipitation of the reduced dendrimers. The CV and NIR results for the various dendrimer generations were quite similar. These results allow insight into t...