Bulk quantities of nitrogen-rich graphitic carbon nitride are synthesized via a facile reactive pyrolysis process with a mixture of melamine and cyanuric chloride as the molecular precursors. Scanning electron microscopy and transmission electron microscopy studies show that micrometer-sized hollow vessels with high aspect ratios have been successfully elaborated without the designed addition of any catalyst or template. The composition of the prepared carbon nitride determined by combustion method is C(3)N(4.91)H(1.00)O(0.22), with the N/C ratio to be 1.64, indicating a high nitrogen content. X-ray diffraction pattern reveals the regular stacking of graphene CN(x) monolayers along the (002) direction with the presence of turbostratic ordering of C and N atoms in the a-b basal planes. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy investigations provide further evidence for graphite-like sp(2)-bonded building blocks based on both triazine and heptazine ring units bridged by 3-fold coordinated nitrogen atoms. The optical properties of the sample are investigated by UV-vis absorption and photoluminescence spectroscopy, which show features characteristic of pi-pi* and n-pi* electronic transitions involving lone pairs of nitrogen atoms. Thermogravimetric analysis curves of the synthesized graphitic carbon nitride hollow vessels show typical weight loss steps related to the volatilization of triazine and heptazine structural units.
Carvone,
a naturally abundant chiral cyclic α,β-unsaturated carbonyl
compound, was chemically transformed into cyclic exo-methylene conjugated dienes. The exo-methylene
group had high reactivity in cationic polymerization and was efficiently
polymerized in a controlled manner via regioselective 1,4-conjugated
additions using initiating systems effective for living cationic polymerization
of vinyl ethers. The obtained polymers with 1,3-cyclohexenyl units
and tetra-substituted olefins in the main chain showed high glass
transition temperatures over 110 °C. The chiral monomer underwent
stereospecific polymerization to result in polymers with low solubility
and weak packing of the rigid main chain in the lamellar layers. The
racemic mixture resulted in soluble amorphous polymers, which were
subsequently hydrogenated into cycloolefin polymers with enhanced
thermal properties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.