2 research outputs found
Correlating Structure with Thermal Properties for a Series of 1‑Alkyl-4-methyl-1,2,4-triazolium Ionic Liquids
Thermal properties (<i>T</i><sub>m</sub> and <i>T</i><sub>d</sub>) are reported for
a series of 1-alkyl-4-methyl-1,2,4-triazolium
ionic liquids where the alkyl chain length R and anion [X<sup>–</sup>] were varied. The highest melting transitions were observed when
a longer alkyl chain or smaller anion was employed. Thermal stability
was the greatest when anions with weak hydrogen bonding capability
were used. Correlations were also made between <sup>1</sup>H NMR chemical
shift values in acetone-<i>d</i><sub>6</sub> and the hydrogen
bonding capability of the anion
Marangoni Instability Driven Surface Relief Grating in an Azobenzene-Containing Polymer Film
The Marangoni effect describes fluid
flow near an interface in
response to a surface tension gradient. Here, we demonstrate that
the Marangoni effect is the underlying mechanism for flow driven feature
formation in an azobenzene-containing polymer film; features formed
in azobenzene-containing polymers are often referred to as surface
relief gratings or SRGs. An amorphous polyÂ(4-(acryloylÂoxyhexylÂoxy)-4′-pentylÂazobenzene)
was synthesized and studied as a model polymer. To isolate the surface
tension driven flow from the surface tension pattern inscription step,
the surface tension gradient was preprogrammed via photoisomerization
of azobenzene in a glassy polymer film without forming topographical
features. Subsequently, the latent image was developed in the absence
of light by annealing above the glass transition temperature where
the polymer is a liquid. The polymer flow direction was controlled
with precision by inducing different surface tension changes in the
exposed regions, in accordance with expectation based on the Marangoni
effect. Finally, the height of the formed features decreased upon
extensive thermal annealing due to capillary leveling with two distinct
rates. A scaling analysis revealed that those rates originated from
dissimilar capillary velocities associated with different azobenzene
isomers