Temperature-dependent formation of dendrimer islands from ring structures

Fang I. Li, Perry H Leo, John A. Barnard

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Previously unobserved high surface mobility and phase transformation phenomena in condensed, micron-scale dendrimer structures are documented using atomic force microscopy. Stratified dendrimer rings (a unique morphology resulting from microdroplet evaporation of dendrimer-alcohol solutions on mica) undergo dramatic temperature, time, and dendrimer-generation-dependent morphological changes associated with large-scale molecular rearrangements and partial melting. These transformations produce ring structures consisting of a highly stable first monolayer of the scalloped structure in equilibrium with spherical cap shaped dendrimer islands that form at the center of each pre-existing scallop (creating a "pearl necklace" structure). A generation-dependent critical temperature for dendrimer melting is determined. As-evaporated structures can be stabilized against thermally driven rearrangements by holding them at room temperature before annealing. Analysis of the dendrimer island shapes reveals a dependence of island contact angle on contact line curvature (island size) that varies systematically with dendrimer generation. A negative line tension, τ is deduced in these systems. The morphological transformations in this system indicate the potential for creating complex, dendrimer-based multilevel structures and macroscopic-scale arrays using, for example, droplet-on-demand or dip pen nanolithography techniques, coupled with appropriate annealing and stabilizing treatments.

Original languageEnglish (US)
Pages (from-to)16497-16504
Number of pages8
JournalJournal of Physical Chemistry B
Volume112
Issue number51
DOIs
StatePublished - Dec 25 2008

Fingerprint

Dendrimers
ring structures
dendrimers
Temperature
temperature
Melting
melting
Annealing
spherical caps
Nanolithography
pens
annealing
Mica
mica
Contacts (fluid mechanics)
Contact angle
phase transformations
Monolayers
Atomic force microscopy
critical temperature

Cite this

Temperature-dependent formation of dendrimer islands from ring structures. / Li, Fang I.; Leo, Perry H; Barnard, John A.

In: Journal of Physical Chemistry B, Vol. 112, No. 51, 25.12.2008, p. 16497-16504.

Research output: Contribution to journalArticle

Li, Fang I. ; Leo, Perry H ; Barnard, John A. / Temperature-dependent formation of dendrimer islands from ring structures. In: Journal of Physical Chemistry B. 2008 ; Vol. 112, No. 51. pp. 16497-16504.
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