Accession Number : ADA333726

Title :   Structural Distortion of Dendrimers on Gold Surfaces: A Tapping-Mode AFM Investigation

Descriptive Note : Technical rept. 1 Aug 97-28 Feb 98

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION DEPT OF CHEMISTRY

Personal Author(s) : Hierlemann, Andreas ; Campbell, Joseph K. ; Baker, Lane A. ; Crooks, Richard M. ; Ricco, Antonio J.

PDF Url : ADA333726

Report Date : 05 JAN 1998

Pagination or Media Count : 15

Abstract : Atomic force microscopy (AFM) investigations of polyamidoamine (PAMAM) Starburst (Trademark) dendrimers, generations 4 and 8 (G4, G8), absorbed on Au (111) surfaces were conducted. By controlling dendrimer concentration and exposure time during adsorption, coverages ranging from completely isolated molecules to a monolayer were prepared. The individual dendrimer molecules forming a monolayer were clearly imaged. Upon exposure to hexadecanethiol, the shapes of individual dendrimers change and they become taller and narrower as more stable thiol-Au bonds replace some of the amine-Au bonds. In the case of monolayers, exposure to hexadecanethiol causes the dendrimers to gradually agglomerate, forming dendrimer "pillars" up to 30 nm in height and freeing progressively more surface area for thiol adsorption.

Descriptors :   *ADSORPTION, *GOLD, STRUCTURAL PROPERTIES, SUBSTRATES, CHEMICAL BONDS, AMINES, THIOLS.

Subject Categories : Polymer Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE