C O M M U N I C A T I O N S
Scheme 3. Polymerization of 1-Octyl-4-vinyl-1,2,3-triazole, 9, to
Give the Corresponding Homopolymer, 11
equivalent of methacrylate or R-methyl styrene systems. The first
step involves in situ generation of an azide derivative (Caution)6
followed by formation of the triazole nucleus. The resulting hydroxy
Figure 2. Structure and functional diversity in the 4-vinyl-1,2,3-triazole
monomer library.
functionalized triazole, 7, can then be readily dehydrated with POCl
to afford a high yield of the desired 1-substituted-4-R-methylvinyl-
,2,3-triazole, 8 (Scheme 2). The corresponding vinyl derivatives
3
1
various functional groups to be prepared in high yields. Subsequent
homo- and copolymerization of these novel functionalized mono-
mers was achieved under “living” conditions utilizing RAFT
techniques to give polymeric materials with unique physical
properties, combining many attractive features of more established
systems. It is anticipated that this new family of vinyl monomers
will significantly extend the range of functional materials that can
be prepared when compared to traditional monomers, such as
styrene, vinylpyridine, and meth/acrylates.
could be prepared easily by applying the same strategy to but-3-
yn-1-ol.
An important aspect of these synthetic strategies is the inherent
versatility in the range of alkyl/aryl halides or mesylates that can
be used as precursors. Moreover, both pathways alleviate the need
for synthesis and isolation of organic azides, which further increases
the range of possible structures while at the same time decreasing
6
safety concerns. As shown in Figure 2, these approaches have
provided access to a spectrum of triazole-based functional mono-
mers with the substituent at N-1 ranging from alkyl/aryl to
heteroatom-containing (cf. meth/acrylate systems).
Acknowledgment. We thank the National Science Foundation
for support of this work (CHE-0514031, DMR 0317514 and the
MRSEC program (UCSB MRL), DMR-0520415) as well as the
Mitsubishi Chemical Company.
Polymerization of the triazole monomers to give both homopoly-
mers as well as copolymers was examined under reversible addition
7
fragmentation chain transfer (RAFT) conditions. For example,
RAFT polymerization of a 500:1 mixture of 9 and an initiating
system consisting of dithioester, 10, and 20 mol % of AIBN (relative
to 10) in DMF at 70 °C resulted in a living polymerization system
with excellent control over molecular weight and polydispersity
Supporting Information Available: Experimental details and
spectroscopic/analytical data for monomers and polymers. This material
is available free of charge via the Internet at http://pubs.acs.org.
References
(Mn(exp) ) 44.9 kDa; Mn(theor) ) 44.0 kDa; PDI ) 1.08). Homopo-
lymerization and copolymerization of all the triazole monomers
shown in Figure 2 under RAFT conditions proceed with a high
degree of control to give materials with a wide range of physical
properties. Significantly, the physical properties of these homo/
copolymers were found to be dramatically influenced by incorpora-
tion of the triazole monomer. To illustrate this point, the homopoly-
mer based on polymerization of the n-octyl derivative, 11, displays
significantly different properties when compared to those of
comparable styrenic, vinyl pyridine, or acrylate-based materials.
For example, the glass transition temperature of 11 is 23 °C,
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while the T values for poly(n-octyl acrylate) and poly(4-octylsty-
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8
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of the polar nature of the triazole nucleus on the physical properties
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in methanol, in sharp contrast to the corresponding octyl-substituted
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which are totally insoluble in methanol. Similarly enhanced
properties were observed for the homopolymer based on the phenyl
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(
(
(
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In summary, we have introduced a new monomer family based
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2
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