19 research outputs found
Self-assembly of tetra(aniline) nanowires in acidic aqueous media with ultrasonic irradiation
An environmentally friendly method is developed to explore the self-assembly of Ph/NH2-capped tetra(aniline) nanowires in acidic aqueous medium with ultrasonic irradiation.</p
Fluorescent Microporous Polyimides based on Perylene and Triazine for Highly CO<sub>2</sub>-Selective Carbon Materials
Carbon dioxide (CO<sub>2</sub>) capture
from point sources like
coal-fired power plants is a potential solution for stabilizing atmospheric
CO<sub>2</sub> content to avoid global warming. Sorbents with high
and reversible CO<sub>2</sub> uptake, high CO<sub>2</sub> selectivity,
good chemical and thermal stability, and low cost are desired for
the separation of CO<sub>2</sub> from N<sub>2</sub> in flue or natural
gas. We report here, for the first time, on the synthesis of new microporous
polyimide (PI) networks from the condensation of perylene-3,4,9,10-tetracarboxylic
dianhydride (PTCDA) and 1,3,5-triazine-2,4,6-triamine (melamine) using
a Lewis acid catalyst zinc acetate/imidazole complex. These PI network
materials, prepared in the absence and presence of dimethyl sulfoxide
(DMSO) as weak solvent template, exhibit strong fluorescence. Nitrogen-containing
carbons can be accessed from our PI networks via a simple thermal
pyrolysis route. The successful construction of new microporous PI
networks and derived N-containing carbons is shown here to provide
promising CO<sub>2</sub> sorbents with high uptake capacities (15
wt %) combined with exceptional selectivities over N<sub>2</sub> (240),
while their fluorescent properties can be exploited for simple sensing
Highly Efficient and Reversible Iodine Capture in Hexaphenylbenzene-Based Conjugated Microporous Polymers
The effective and safe capture and
storage of radioactive iodine (<sup>129</sup>I or <sup>131</sup>I)
is of significant importance during nuclear waste storage and nuclear
energy generation. Here we present detailed evidence of highly efficient
and reversible iodine capture in hexaphenylÂbenzene-based conjugated
microporous polymers (HCMPs), synthesized via BuchwaldâHartwig
(BH) cross-coupling of a hexakisÂ(4-bromoÂphenyl)Âbenzene (HBB)
core and aryl diamine linkers. The HCMPs present moderate surface
areas up to 430 m<sup>2</sup> g<sup>â1</sup>, with narrow pore
size distribution and uniform ultramicropore sizes of less than 1
nm. Porous properties are controlled by the strut lengths and rigidities
of linkers, while porosity and uptake properties can be tuned by changing
the oxidation state of the HCMPs. The presence of a high number of
amine functional groups combined with microporosity provides the HCMPs
with extremely high iodine affinity with uptake capacities up to 336
wt %, which is to the best of our knowledge the highest reported to
date. Two ways to release the adsorbed iodine were explored: either
slow release into ethanol or quick release upon heating (with a high
degree of control). Spectral studies indicate that the combination
of microporosity, amine functionality, and abundant Ï-electrons
ensured well-defined hostâguest interactions and controlled
uptake of iodine. In addition, the HCMPs could be recycled while maintaining
90% iodine uptake capacity (up to 295%). We envisage wider application
of these materials in the facile uptake and removal of unwanted oxidants
from the environment
Towards direct laser writing of actively tuneable three-dimensional photonic crystals
3D printing and actively switchable redoxâactive oligo(aniline)âbased materials are combined to create novel tuneable 3D photonic materials. By a direct laser writing process, switchable functional structures with submicrometer features are fabricated. Reversible changes in the refractive index of the written materials are generated with negligible size changes