5 research outputs found
Synthesis of 1,3,5-Tris(phenylamino) Benzene Derivatives and Experimental and Theoretical Investigations of Their Antioxidation Mechanism
1,3,5-TrisÂ(phenylamino) benzene and
a series of its substitution
derivatives were synthesized. The structure of the as-synthesized
products was confirmed by nuclear magnetic resonance spectroscopy
and high resolution mass spectra. Moreover, the antioxidation behavior
of 1,3,5-trisÂ(phenylamino) benzene and its substitution derivatives
as antioxidants in several ester oils was evaluated by a rotary oxygen
bomb test and pressurized differential scanning calorimetry, while
theoretical calculations were conducted to examine their antioxidation
mechanism. It was found that 1,3,5-trisÂ(phenylamino) benzene exhibits
better antioxidation ability at elevated temperature (150 and 210
°C) than commonly used commercial antioxidant diphenylamine.
In the meantime, the substitution groups exhibit significant effects
on the antioxidation behavior of 1,3,5-trisÂ(phenylamino) benzene and
its derivatives. This is because the substituents result in changes
in the molecular structure and electronic effect of the as-synthesized
products, thereby causing s change in their antioxidation behavior
Enzymatic Oligomerization of <i>p</i>‑Methoxyphenol and Phenylamine Providing Poly(<i>p</i>‑methoxyphenol-phenylamine) with Improved Antioxidant Performance in Ester Oils
PolyÂ(<i>p</i>-methoxyphenol-phenylamine), denoted as
PÂ(MOP-PA), was synthesized via the enzymatic oligomerization of <i>p</i>-methoxyphenol and phenylamine monomers in the presence
of horseradish. The structure of the as-synthesized product was confirmed
by Fourier transform infrared spectrometry, time-of-flight mass spectrometry,
and elemental analysis, and the oligomerization process was studied
by high-performance liquid chromatography. Moreover, the antioxidation
behavior of PÂ(MOP-PA) as an antioxidant in several ester oils was
evaluated by rotary oxygen bomb test and pressurized differential
scanning calorimetry, and its antioxidant mechanism was discussed.
It was found that, as the antioxidant in various base oils, PÂ(MOP-PA)
exhibits excellent antioxidation ability at elevated temperatures
of 150 and 210 °C. In addition, PÂ(MOP-PA) has an antioxidant
ability that is better than that of polyÂ(<i>p</i>-methoxyphenol),
and it exhibits an antioxidation ability in synthetic ester oil, such
as di-iso-octyl sebacate, that is much better than that of several
commonly used commercial hindered phenolic antioxidants
Tribological Properties of Tungsten Disulfide Nanoparticles Surface-Capped by Oleylamine and Maleic Anhydride Dodecyl Ester as Additive in Diisooctylsebacate
Oleylamine
(OM) and maleic anhydride dodecyl ester (MADE, synthesized
at our laboratory) were adopted as the surface modifiers to prepare
OM/MADE-capped tungsten disulfide (WS<sub>2</sub>) nanoparticles.
An X-ray diffractometer and a transmission electron microscope were
performed to analyze the microstructure and phase ingredients of the
OM/MADE-capped WS<sub>2</sub> nanoparticles. Moreover, a four-ball
friction and wear tester and a reciprocating tribometer were employed
to evaluate the tribological properties of the surface-capped WS<sub>2</sub> nanoparticles as the lubricant additive in diisooctylsebacate
(DIOS) from room temperature to 150 °C. The morphology of the
worn steel surfaces and wear scars and their chemical states were
investigated with a scanning electron microscope, three-dimensional
profilometry, and an X-ray photoelectron spectroscope. Results show
that OM-capped WS<sub>2</sub> nanoparticles nearly have no effect
on the tribological properties of the DIOS base oil. The OM/MADE-capped
WS<sub>2</sub> nanoparticles added in the same base stock at a concentration
of 2.0% (mass fraction), however, exhibit good dispersibility and
result in greatly improved tribological properties. The reason lies
in that, after surface-capping by MADE containing polar group and
OM containing coordination group, the OM/MADE-capped WS<sub>2</sub> particulates added in the base oil are well adsorbed on the sliding
surfaces of the steel–steel contact to afford a chemisorption
film with a low shear force. At the same time, OM/MADE-capped WS<sub>2</sub> nanoparticles as the additive in DIOS base oil take part
in tribochemical reactions to form tribofilm composed of WO<sub>3</sub> and iron oxides on sliding surfaces, which also contributes to reducing
the friction and wear of the steel sliding contact
Ferromagnetism and Microwave Electromagnetism of Iron-Doped Titanium Nitride Nanocrystals
Titanium nitride (TiN) nanocrystals doped with different
dosages
of iron were prepared by calcinating nanotubular titanic acid precursor
in flowing ammonia. The structure of as-prepared Fe-doped TiN nanocrystals
was characterized, and their ferromagnetism and microwave electromagnetism
were investigated. It has been found that as-prepared Fe-doped TiN
nanocrystals exhibit distinct room temperature ferromagnetic properties
and improved microwave electromagnetic loss behavior when compared
with the undoped counterpart. Considering the crystal structure and
chemical feature of as-synthesized products, we suppose that structural
defects are responsible for the observed ferromagnetism and microwave
electromagnetism of as-synthesized Fe-doped TiN, and it may be feasible
to tune the magnetic and electromagnetic properties by manipulating
the generation of the structural defects. Hopefully, the present research
is to shed light on Fe-doped TiN nanocrystal as a promising microwave
absorption material and to help acquiring insights into the origin
of ferromagnetism and microwave electromagnetism in a broad range
of nanostructures, thereby broadening the scope of dilute magnetic
and electromagnetic wave absorbing materials
Preparation of Graphene Sheets by Electrochemical Exfoliation of Graphite in Confined Space and Their Application in Transparent Conductive Films
A novel
electrochemical exfoliation mode was established to prepare
graphene sheets efficiently with potential applications in transparent
conductive films. The graphite electrode was coated with paraffin
to keep the electrochemical exfoliation in confined space in the presence
of concentrated sodium hydroxide as the electrolyte, yielding ∼100%
low-defect (the D band to G band intensity ratio, <i>I</i><sub>D</sub>/<i>I</i><sub>G</sub> = 0.26) graphene sheets.
Furthermore, ozone was first detected with ozone test strips, and
the effect of ozone on the exfoliation of graphite foil and the microstructure
of the as-prepared graphene sheets was investigated. Findings indicate
that upon applying a low voltage (3 V) on the graphite foil partially
coated with paraffin wax that the coating can prevent the insufficiently
intercalated graphite sheets from prematurely peeling off from the
graphite electrode thereby affording few-layer (<5 layers) holey
graphene sheets in a yield of as much as 60%. Besides, the ozone generated
during the electrochemical exfoliation process plays a crucial role
in the exfoliation of graphite, and the amount of defect in the as-prepared
graphene sheets is dependent on electrolytic potential and electrode
distance. Moreover, the graphene-based transparent conductive films
prepared by simple modified vacuum filtration exhibit an excellent
transparency and a low sheet resistance after being treated with NH<sub>4</sub>NO<sub>3</sub> and annealing (∼1.21 kΩ/□
at ∼72.4% transmittance)