Page 168 - Science at the nanoscale

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Formation and Self-Assembly at the Nanoscale
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these particles are enclosed by surface capping agents with long
hydrocarbon chains.
Further Reading
G. Cao, Nanostructures and Nanomaterials — Synthesis, Properties
and Applications (Imperial College Press, 2004).
C. P. Poole Jr., F. J. Owens, Introduction to Nanotechnology (Wiley,
2003).
R. A. L. Jones, Soft Machines — Nanotechnology and Life (Oxford
University Press, 2004).
Exercises
∗
7.1. The critical radius r in Fig. 7.3 presents a practical limit
for the smallest size particles that can be prepared in the
system. Discuss what other ways that one can use to
reduce the critical size as well as the critical Gibbs energy
∗
∆G .
7.2. Ellipsometric measurements yield a thickness of 21.1 ˚ A
for the adsorbed SAM of hexadecanethiol molecules. An
extended hexadecanethiol molecule is estimated to be
24.5 ˚ A in length. What is the tilt angle of the adsorbed
monolayer on the substrate?
7.3. A given surfactant molecule has head group with a cross-
2
sectional area of 6 ˚ A . A solution of the surfactant in a
nonpolar solvent is dispersed slowly onto the surface of
water. The volatile solvent evaporates immediately, leav-
ing behind a self-assembly of the surfactant molecules
on the surface. (i) Calculate the number of surfac- ch07
tant molecules that will be dispersed in a self-assembled
monolayer film of dimensions 15 × 30 cm. (ii) What is the
volume of 0.1 M of the surfactant solution needed to pro-
duce the film in (i)?