C O M M U N I C A T I O N S
microlenses could be obtained by filling, curing, and peeling. Such
arrays could functionally be similar to the calcite microlenses that
are found on the arms of brittle stars.20
In conclusion, we have prepared self-assembled bubble arrays
from an azide-substituted PPE 4. Thermal cross-linking of these
arrays leads to their collapse under formation of self-assembled
picoliter hole arrays with a density of approximately 40 000 holes/
mm2. These microstructures have great potential as microanalytical
tools and as matrices for the fabrication of microlens or micro-
OLED arrays.
Acknowledgment. U.B., J.W., and B.E. thank the Department
of Energy (DE-FG02-03ER46029) and the National Science
Foundation (CHE 0138659) for generous funding. L.S., J.P., and
M.S. thank the National Science Foundation (DMR 00962640) and
the PRF for generous support. M.S. thanks Prof. Royce Murray
(UNC) for discussions on picoliter breakers.
Supporting Information Available: Synthesis and characterization
of polymer 4 and monomer 2 (PDF). This material is available free of
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Figure 2. Cross section of the bubble array. x and z axes are identical to
those in Figure 1. Top: Interconnected bubble arrays from 4 “as obtained”.
Bottom: The array was heated from 25 to 300 °C for 60 min, and the
confocal laser micrograph was taken after cooling the sample to ambient
temperature. Scale bar ) 5 µm. The shrinking of the bubble arrays in the
third dimension (thickness direction) is visible. Cup-shaped, isolated
picovials or picoliter beakers have formed.
Pt-catalyzed cross-linking.19 The use of the cross-linked azide-PPE
microcups as matrix is particularly interesting, because arrays of
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