8 research outputs found
Can Chain-Reaction Polymerization of Octadecyl Acrylate Occur in Crystal?
Octadecyl acrylate
was proven to exist in rotator phases, and the
mechanism of its chain-reaction photopolymerization was revealed.
The polymorphic behavior of octadecyl acrylate was studied by differential
scanning calorimeter (DSC) and X-ray diffraction, which concluded
that octadecyl acrylate exhibits two rotator phases (<i>R</i><sub>II</sub> and <i>R</i><sub>I</sub>), one orthorhombic
crystal phase (<i>C</i><sub>ort</sub>), and one triclinic
crystal phase (<i>C</i><sub>tri</sub>) phase. The chain-reaction
photopolymerization of four phases of octadecyl acrylate were studied
by photo-DSC, and the theoretical possibilities of one-dimension chain
propagation in <i>R</i><sub>II</sub>, <i>R</i><sub>I</sub>, and <i>C</i><sub>ort</sub> phases were analyzed
by using the molecular dynamics simulation results. Combining the
experimental and calculation results, the chain-reaction polymerization
mechanism either intralayer or interlayer was discussed and disclosed.
The question of whether the chain-reaction polymerization of octadecyl
acrylate can occur in crystal was answered, and the reason was explained
0 + 0 = 2: Changeover of Stability and Photopolymerization Kinetics for the Rotator Phase of Long-Chain Acrylate through the Ultra-Addition Effect in Binary Systems
The
stability and lowest existing temperature for the rotator phase
of long-chain acrylate were improved remarkably simply through the
ultra-addition effect of physical blending of two long-chain acrylates,
which leads to a wider operation window and better rotator-state photopolymerization.
Hexadecyl acrylate (HDA) and tetradecyl acrylate (TDA) were proved
existing rotator phase like previously reported octadecyl acrylate
(ODA). The binary rotator phase systems were constructed by mixing
HDA or TDA with ODA and investigated in detail through thermal analysis,
X-ray diffraction, and photopolymerization kinetics. The chain-reaction
photopolymerization conversion of the binary system significantly
increased to 60% from near 0 for pure acrylate, which realized “0
+ 0 = 2”. The mechanism of such an ultra-addition effect was
explained on the basis of X-ray diffraction data and calculation of
the geometric model. The effect of difference in chain length between
two components on this enhancement was studied, and a threshold value
was found
Cationic Ring-Opening Photopolymerization of Long-Chain Epoxides in the Rotator Phase: Confirmation, Mechanism, and Combination
Rotator-phase photopolymerization has been developed
in the field
of free-radical addition polymerization since the photopolymerization
in the rotator phase was first proposed, and other mechanisms urgently
need to be extended. Herein, four long-chain glycidyl ethers were
synthesized, and their polymorphic behavior was studied by differential
scanning calorimetry and X-ray diffraction. Among all, the octadecyl
glycidyl ether (OGE) and the hexadecyl glycidyl ether (HGE) are proven
existing rotator phases. The cationic ring-opening photopolymerization
of the OGE in the rotator phase was achieved, and the highest conversion
reached 68.6% at 30 °C, which is even higher than that of liquid-state
photopolymerization at adjacent higher temperatures (27.2% at 40 °C).
The mechanism was discussed and explained with the aid of a molecular
dynamic simulation. In order to further develop the cationic ring-opening
photopolymerization in rotator phases at relatively low temperatures,
three types of long-chain compounds were chosen to separately blend
with the OGE to construct binary systems. The conversion of the OGE
at 20 °C (17% in the pure OGE system) could be obviously improved
in all binary systems, and the maximum conversion could reach 56%.
Subsequently, the interactions of different long-chain compounds on
the OGE and the effect on polymerization behavior are both discussed
Cationic Ring-Opening Photopolymerization of Long-Chain Epoxides in the Rotator Phase: Confirmation, Mechanism, and Combination
Rotator-phase photopolymerization has been developed
in the field
of free-radical addition polymerization since the photopolymerization
in the rotator phase was first proposed, and other mechanisms urgently
need to be extended. Herein, four long-chain glycidyl ethers were
synthesized, and their polymorphic behavior was studied by differential
scanning calorimetry and X-ray diffraction. Among all, the octadecyl
glycidyl ether (OGE) and the hexadecyl glycidyl ether (HGE) are proven
existing rotator phases. The cationic ring-opening photopolymerization
of the OGE in the rotator phase was achieved, and the highest conversion
reached 68.6% at 30 °C, which is even higher than that of liquid-state
photopolymerization at adjacent higher temperatures (27.2% at 40 °C).
The mechanism was discussed and explained with the aid of a molecular
dynamic simulation. In order to further develop the cationic ring-opening
photopolymerization in rotator phases at relatively low temperatures,
three types of long-chain compounds were chosen to separately blend
with the OGE to construct binary systems. The conversion of the OGE
at 20 °C (17% in the pure OGE system) could be obviously improved
in all binary systems, and the maximum conversion could reach 56%.
Subsequently, the interactions of different long-chain compounds on
the OGE and the effect on polymerization behavior are both discussed
Cationic Ring-Opening Photopolymerization of Long-Chain Epoxides in the Rotator Phase: Confirmation, Mechanism, and Combination
Rotator-phase photopolymerization has been developed
in the field
of free-radical addition polymerization since the photopolymerization
in the rotator phase was first proposed, and other mechanisms urgently
need to be extended. Herein, four long-chain glycidyl ethers were
synthesized, and their polymorphic behavior was studied by differential
scanning calorimetry and X-ray diffraction. Among all, the octadecyl
glycidyl ether (OGE) and the hexadecyl glycidyl ether (HGE) are proven
existing rotator phases. The cationic ring-opening photopolymerization
of the OGE in the rotator phase was achieved, and the highest conversion
reached 68.6% at 30 °C, which is even higher than that of liquid-state
photopolymerization at adjacent higher temperatures (27.2% at 40 °C).
The mechanism was discussed and explained with the aid of a molecular
dynamic simulation. In order to further develop the cationic ring-opening
photopolymerization in rotator phases at relatively low temperatures,
three types of long-chain compounds were chosen to separately blend
with the OGE to construct binary systems. The conversion of the OGE
at 20 °C (17% in the pure OGE system) could be obviously improved
in all binary systems, and the maximum conversion could reach 56%.
Subsequently, the interactions of different long-chain compounds on
the OGE and the effect on polymerization behavior are both discussed
Cationic Ring-Opening Photopolymerization of Long-Chain Epoxides in the Rotator Phase: Confirmation, Mechanism, and Combination
Rotator-phase photopolymerization has been developed
in the field
of free-radical addition polymerization since the photopolymerization
in the rotator phase was first proposed, and other mechanisms urgently
need to be extended. Herein, four long-chain glycidyl ethers were
synthesized, and their polymorphic behavior was studied by differential
scanning calorimetry and X-ray diffraction. Among all, the octadecyl
glycidyl ether (OGE) and the hexadecyl glycidyl ether (HGE) are proven
existing rotator phases. The cationic ring-opening photopolymerization
of the OGE in the rotator phase was achieved, and the highest conversion
reached 68.6% at 30 °C, which is even higher than that of liquid-state
photopolymerization at adjacent higher temperatures (27.2% at 40 °C).
The mechanism was discussed and explained with the aid of a molecular
dynamic simulation. In order to further develop the cationic ring-opening
photopolymerization in rotator phases at relatively low temperatures,
three types of long-chain compounds were chosen to separately blend
with the OGE to construct binary systems. The conversion of the OGE
at 20 °C (17% in the pure OGE system) could be obviously improved
in all binary systems, and the maximum conversion could reach 56%.
Subsequently, the interactions of different long-chain compounds on
the OGE and the effect on polymerization behavior are both discussed
Cationic Ring-Opening Photopolymerization of Long-Chain Epoxides in the Rotator Phase: Confirmation, Mechanism, and Combination
Rotator-phase photopolymerization has been developed
in the field
of free-radical addition polymerization since the photopolymerization
in the rotator phase was first proposed, and other mechanisms urgently
need to be extended. Herein, four long-chain glycidyl ethers were
synthesized, and their polymorphic behavior was studied by differential
scanning calorimetry and X-ray diffraction. Among all, the octadecyl
glycidyl ether (OGE) and the hexadecyl glycidyl ether (HGE) are proven
existing rotator phases. The cationic ring-opening photopolymerization
of the OGE in the rotator phase was achieved, and the highest conversion
reached 68.6% at 30 °C, which is even higher than that of liquid-state
photopolymerization at adjacent higher temperatures (27.2% at 40 °C).
The mechanism was discussed and explained with the aid of a molecular
dynamic simulation. In order to further develop the cationic ring-opening
photopolymerization in rotator phases at relatively low temperatures,
three types of long-chain compounds were chosen to separately blend
with the OGE to construct binary systems. The conversion of the OGE
at 20 °C (17% in the pure OGE system) could be obviously improved
in all binary systems, and the maximum conversion could reach 56%.
Subsequently, the interactions of different long-chain compounds on
the OGE and the effect on polymerization behavior are both discussed
Thermal Properties and Kinetics of Al/α-MnO2 Nanostructure Thermite
<div><p>In this work, thermal properties and kinetics of Al-nanoparticles/α-MnO2 nanorods thermite were reported. The α-MnO2 nanorods were synthesized using a hydrothermal method and were characterized by X-ray powder diffraction (XRD) and X-ray photoelectron spectra (XPS), then combined with Al nanoparticles based on the ultrasonic mixing method to prepare the nanostructure thermite. Besides, both pure components and mixture were characterized by field emission scanning electron microscopy (FE-SEM) to observe their morphologies and structures. Subsequently, the thermal properties of Al/α-MnO2 nanostructure thermite were studied on the basis of thermogravimetric-differential scanning calorimetry (TG-DSC). According to the TG-DSC tests, the calculation results of activation energy for kinetics of Al/α-MnO2 thermite were obtained using different isoconversional methods. It was found that Al/α-MnO2 nanostructure thermite has high heat release and low onset temperature, and the heat release of the nanostructure thermite was approximately 1146.6 J g -1.</p></div