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Zachary M Fresco

Publications and source records attributed to Zachary M Fresco.

4 recordsLinked to original sources
PubMed2005

Selective surface activation of a functional monolayer for the fabrication of nanometer scale thiol patterns and directed self-assembly of gold nanoparticles.

Application of a voltage bias between the tip of an atomic force microscope (AFM) and a silicon substrate causes the localized modification of a specially designed self-assembled monolayer (SAM), transforming a surface-bound thiocarbonate into a surface-bound thiol. The resulting surface-bound thiols are used to direct the patternwise self-assembly of gold nanoparticles (AuNPs). This methodology is applied to deposit individual AuNPs onto a surface with nanometer precision and to produce 10 nm lines of closely spaced AuNPs that are a single nanoparticle in width.

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PubMed2005

A dendronized polymer is a single-molecule glass.

The molecular architecture of dendronized polymers can be tuned to obtain nanoscale objects with desired properties. In this paper, we bring together experiments and computer simulations to study the thermodynamic and dynamic properties of a single dendronized polymer chain. We find that, upon changing certain architectural features, dynamic correlations characterizing backbone conformational fluctuations of a dendronized polymer exhibit dynamics akin to glass-forming bulk liquids. Thus, a dendronized polymer chain is a novel macromolecule that is a single-molecule glass. Over a range of conditions that lead to glassy dynamics, there does not appear to be any thermodynamic singularities. We discuss how a dendronized polymer is a molecular system that can directly test different models of glassy dynamics. We also show that defect densities characteristic of typical synthesis conditions do not alter the material properties of dendronized polymers.

Journal Article↗
PubMed2004

AFM-induced amine deprotection: triggering localized bond cleavage by application of tip/substrate voltage bias for the surface self-assembly of nanosized dendritic objects.

An alpha,alpha-dimethyl-3,5-dimethoxybenzyloxycarbonyl (DDZ)-protected amine monolayer can be selectively deprotected by the application of a voltage bias from a conducting AFM tip to afford localized nanoscale patterns that can be visualized by self-assembly of dendritic molecular objects with terminal carboxylic acid groups and different aspect ratios.

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