Polynorbornene-Based Double Stranded Ladderphanes with Cubane, Tricyclooctadiene, and Cyclooctatetraene Linkers
Date Issued
2012
Date
2012
Author(s)
Yeh, Nai-Hua
Abstract
Double stranded polybisnorbornene-based ladderphanes having different linkers,
cubane and cyclooctatetraene, are synthesized by Grubbs-I catalyst-promoted ring
opening metathesis polymerizations. Attempts to polymerize the
tricyclooctadiene-appended polynorbornene are not successful. The polymer with the
tricyclooctadiene pending group was obtained from the rhodium-catalyzed
isomerization of double stranded polybisnorbornene having cubane linker. The
polymer structures could be confirmed by nuclear magnetic resonance (NMR)
spectroscopy. Ethanolysis of polybisnorbornenes indicates that these three polymers
would be double stranded ladderphanes.
Interestingly, the tricyclooctadiene skeleton may undergo extrusion of a C2H2
moiety upon treatment with stoichiometric amount of Grubbs-I catalyst to give
α,α’−diacetoxyl-p-xylene.
The scanning tunneling microscopic (STM) image of the cubane-appended
polymeric ladderphanes suggests that these polymers, like other analogous, tend to
aggregate in an ordered manner on the highly ordered pyrolytic graphite (HOPG)
surface. As shown in Figure, dark part separates each stripe into two symmetrical
parts. The cubane moiety is nonconductive, which would match cubane part of double
stranded ladderphane.
Thermogravimetric analysis (TGA) studies indicate that theses polymers are
thermally stable until about 250 oC.
Subjects
cubane
ROMP
rhodium-catalyst
Type
thesis
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