Synthesis of 1D Polymer/Zeolite Nanocomposites under High Pressure

Recently, simple carbon based polymers
have been synthesized at
high pressures in silicalite, a pure SiO2 zeolite with
a 3D system of mutually interconnected microchannels. These protocols
permitted otherwise unstable polymers to be stabilized and protected
from the atmosphere and to obtain an entirely novel class of nanocomposites
with modified physical properties. In these 3-D systems, channel interconnection
may prevent ideal, isolated polymer chains to be obtained. In this
work, the high pressure (5–10 GPa) synthesis of two archetypal,
linear polymers polyacetylene (PA) and polycarbonyl (pCO) in the 1D
channel system of the pure SiO2 zeolite ZSM-22 (TON) has
been performed. The two resulting nanocomposites PA/TON and pCO/TON
are organic/inorganic composite materials, which are good candidates
as highly directional semiconductors and high energy density materials,
respectively. The synthesis was performed in diamond anvil cells,
starting from dense C2H2 and CO, confined in
ZSM-22, and the nanocomposites were recovered at ambient conditions.
The monomer polymerization was proven by IR spectroscopy and synchrotron
X-ray diffraction measurements. DFT calculations were performed in
order to obtain insight about the configurations of the 1D embedded
polymers.