JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 137
·期 38
·49143
·
IF 2.52
Qian Zhang,Guokang Chen,Kun Wu,Jun Shi,Liyan Liang,Mangeng Lu
A biphenyl type liquid crystal epoxy (LCE) monomer 4,4′-di(2,3-epoxyhexyloxy)biphenyl (LCBP4) containing flexible chain was synthesized and the curing behavior was investigated using 4,4′-diaminodiphenylmethane (DDM) as the curing agent. The effect of curing condition on the formation of the liquid crystalline phase was examined. The cured samples show good mechanical properties and thermal stabilities. Moreover, the relationship between thermal conductivity and structure of liquid crystalline domain was also discussed. The samples show high thermal conductivity up to 0.28–0.31 W/(m*K), which is 1.5 times as high as that of conventional epoxy systems. In addition, thermal conductive filler, Al 2 O 3 , was introduced into LCBP4/DDM to obtain higher thermal conductive composites. When the content of Al 2 O 3 was 80 wt%, the thermal conductivity of the composite reached to 1.86 W/(m*K), while that of diglycidyl ether of bisphenol A (Bis-A) epoxy resin/DDM/Al 2 O 3 was 1.15 W/(m*K). Compared with Bis-A epoxy resin, the formation of liquid crystal domains in the cured LCE resin enhanced the thermal conductivity synergistically with the presence of Al 2 O 3 . Furthermore, the introduction of Al 2 O 3 also slightly increased the thermal stabilities of the cured LCE.
研究领域:
材料科学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
CELLULOSE
·
2019
·Vol. 26
·期 15
·8351-8365
·
IF 3.917
Jia Wei,Liu Yun
Abstract We systematically compare the different properties of cellulose nanocrystals (CNCs) obtained by oxalic acid and sulfuric acid hydrolysis methods. The variant characteristics of two kinds of CNCs were confirmed by XRD, DLS, Zeta, TGA, and SEM techniques. When CNCs were mixed with PEG, and the chiral nematic tissue of CNCs was retained in the solid film to observe the liquid crystal phase by evaporation-induced self-assembly. The brilliant snowflake-like pattern of CNC film was observed through oxalic acid instead of sulfuric acid. More importantly, carboxylated CNCs prepared by oxalic acid was easily formed a liquid crystal phase by adding cationic solutions into 1.27% CNC solution. The extra properties of CNCs obtained by oxalate dihydrate contribute to its potential application prospects in optical devices and chiral separation. Graphic abstract
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Energy Materials
·
2021
·
IF 6.024
Haoran Xu,Sheng Chen,Shaonan Chen,Rui Qiao,Hui Li,Hang Luo,Dou Zhang
When one considers that outstanding dielectric polymers satisfy the developed requirements in the electronic and electrical industries, it is necessary to explore the structure–property relationship of all-organic polymer dielectrics. In this paper, two kinds of side-chain sulfonyl-containing dipolar polymers based on polyolefin main chains, poly{2,5-bis[(4-(methylsulfonyl)phenyl)oxycarbonyl]styrenes} (PBSO2) and poly{2,5-bis[(4-(methylsulfonyl)ethyl)oxycarbonyl]styrenes} (PESO2), were prepared via radical polymerization. The effect of the side-chain structure on the phase behavior, phase structure, dielectric property, and energy storage of dipolar polymers was investigated. The results showed that PBSO2 possessed a high glass transition temperature (Tg ≈ 195 °C) and formed the columnar nematic phase owing to the rigid side-chain structure. A dielectric constant of 20.8 (25 °C, 103 Hz) was obtained for the polymer PBSO2 due to the highly orientational polarization and the possible interfacial polarization between the amorphous phase and liquid crystalline phase, which is 18% higher than that of PESO2. However, PBSO2 exhibited a low breakdown strength because of the low band gap of ≈3.46 eV and brittleness of the film. In contrast, a low Tg of 78 °C and isotropic phase were found in the polymer PESO2. In addition, a discharge energy density of 6.2 J/m3 at 270 MV/m was achieved, which was attributed to the high dipole density. This study indicates that it is effective to improve the dielectric constant by introducing a liquid crystalline phase into a dipolar polymer, which offers a route for synthesizing high-performance dielectric polymers.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
LIQUID CRYSTALS
·
2020
·
IF 2.908
Ying Liu,Xiaoshan Zhen,Sheng Gao,Qingbin Xue,Zaijun Lu
To study the mesophase formation mechanism of polybenzoxazine, a novel linear benzoxazine oligomer bearing cholesteryl side groups [poly(PC-AC)] was designed and synthesised through thermally activated ring-opening polymerisation of a monofunctional benzoxazine monomer (PC-AC). The PC-AC was obtained by Mannich condensation reaction using mesomorphic amine of cholesteryl 4-aminobenzoate, p-cresol and paraformaldehyde as starting materials. During the isothermal polymerisation of PC-AC monomer, the phase evolution from a crystal phase to an isotropic molten phase and then to a liquid crystal (LC) phase was observed. Since it is PC-AC oligomers that form the LC phase, ‘polymerisation-induced LC’ mechanism is put forward. We believe that the structure factors including the confined formation of intramolecular hydrogen bonding and the side chain position of mesogenic units also play an important role in the formation of the LC phase. Furthermore, poly(PC-AC) exhibits a smectic mesophase. This work provides new insight into the LC phase formation mechanism of polybenzoxazines. This is very helpful to guide the rational design and synthesis of polymers with high thermal conductivity and high-temperature resistance.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Meng Fu,Xiangming Li,Zepeng Zhang
Here we demonstrate a novel magnetic functional material composed of montmorillonite (Mt) with superparamagnetic coating Fe 3 O 4 dispersed in the aqueous solution. Colloidal stability can be obtained through keeping 2 < pH < 3. After applying an external magnetic field, Mt@Fe 3 O 4 exhibits long-range order and liquid crystalline phase. The transmittance of the liquid crystal is dependent on the solid content of Mt@Fe 3 O 4 , magnetic field strength and magnetic field direction. We also observe reflective phenomena when we modulate the magnetic field. The photonic bandgap can be tuned by changing the angle between incident light and magnetic field. The varying observation points also make a difference to the reflection. This facile approach for fabricating Mt@Fe 3 O 4 with ordered periodic structures and optically tunable property is of interest for a variety of advanced optics applications with low cost and environment-friendly.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2021
·Vol. 36
·期 2
·230-238
·
IF 0.957
Xiong Yan,Tan Peng,Liu Qi,Liu Kaixuan,Tan Junjun
Hydroxyapatite (HA) nanorods were synthesized using a citrate-assisted hydrothermal method. NaH 2 PO 4 , Na 2 HPO 4 , and Na 3 PO 4 were used as the phosphate sources and the influences of pH value were investigated. The XRD results show that pure hexagonal HA can be synthesized using Na 3 PO 4 ·12H 2 O as the phosphate source with the citrate solution pH ranging from 5.0 to 7.6. The zeta potential evaluation demonstrates that as-synthesized HA nanorods are colloidally stable and the aqueous dispersion can be maintained homogenous without any sediment or creaming for more than at least a month. The Ca/P molar ratio of the HA nanorods is about 1.60, indicating that the HA nanorods are calcium-deficient hydroxyapatite. Besides, owing to the excellent colloidal stability and rod-like morphology with a high aspect ratio (>6), the HA aqueous dispersion undergoes a phase transition from an isotropic state to a liquid crystalline state upon increasing the particle concentration to 17wt%. The completely liquid crystalline phase forms when the particle concentration reaches above 30wt%.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2014
·
IF 2.354
Yajie Jiang,Tao Geng,Qiuxiao Li,Guojin Li,Hongbin Ju
The salt-free catanionic surfactant dodecyltrimethylammonium decanoate (DTAD) was synthesized by a novel method. Phase behavior and phase structure of DTAD with water at full concentration range were studied at 20–45 °C, using differential scanning calorimetry (DSC), freeze-fracture transmission electron microscopy (FF-TEM), polarization microscopy, and small-angle X-ray diffraction (XRD) techniques. The DTAD–water system formed a large aqueous multi-phase region, a large lamellar liquid crystal (L α phase) region, and a hydrated crystal phase. The densely packed vesicles and the lamellar structure induced the formation of aqueous multi-phase region. With increasing temperature, the multi-phase region and the L α phase region reduced, and the isotropic solution phase (L 1 phase) appeared.
研究领域:
表面化学
·
胶体科学
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale Advances
·
2020
·Vol. 2
·期 4
·1523-1530
·
IF 0
Ting Qu,Song Guan,Xiaoxiong Zheng,Aihua Chen
The highly ordered perpendicularly aligned cylindrical and lamellar microdomains within block copolymer (BCP) films have important applications in diverse fields. However, the fast normal orientation of self-assembled nanostructures on arbitrary substrates without tedious pre- and postprocessing has been a challenging issue in manufacturing miniaturized devices. Here, we outline the potential for extending the hierarchical self-assembly within azobenzene-containing PS-b-PMA(Az) films to inherently assist in the formation of normally aligned domains using a rapid thermal annealing process (140 °C for 5 min). Liquid crystalline (LC) mesogens in PS-b-PMA(Az) films self-assemble to form a parallelly aligned sematic phase after thermal annealing, as confirmed by grazing-incidence small-angle X-ray scattering (GISAXS), wide-angle X-ray diffraction (WAXD) and ultraviolet-visible (UV-vis) spectra. This sub-phase contributes to broadening of the PS-cylinder-phase window (0.083 ≤ fPS < 0.49) and ∼12 nm PS cylinder structures. Perpendicular cylinders or lamellae are observed on various substrates, such as silicon wafers, flexible polyethylene terephthalate (PET) sheets and conductive aluminum foils. Additionally, the good reactive ion etching (RIE) rate difference between the two blocks makes these BCPs more attractive for advancing the field of BCP lithographic applications for fabricating flexible microelectronic devices.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
REACTIVE & FUNCTIONAL POLYMERS
·
2018
·
IF 2.975
Huan Liu,Qing-Quan Liu,Li Tian,Lin-Yan Wang,Kai Xu,Qian-Xin Chen,Bao-Li Ou
A Schiff-base moiety was introduced into the chemical structure of benzoxazine through the Mannich reaction . With alternative imine groups (C N) and benzene rings in the chain segment, these highly π-conjugated systems favored the formation of strong intermolecular hydrogen bonds to the hydroxyl groups generated during polymerization, leading to a thermally initiated cationic polymerization mechanism. Compared with the bisphenol-A-based benzoxazine, the benzoxazine with the Schiff-base moiety needs higher energy to facilitate the realization of polymerization and to increase polymerization degree. In addition to the influences on the polymerization, the highly π-conjugated Schiff-base acting as a mesogenic moiety is found to form liquid crystal (LC) phases, like the nematic phase and smectic phase . Interestingly, some LC-rich domains can be stabilized by the polybenzoxazine network, which will contribute to form nitrogen-rich ordered porous carbon at the carbonization stage. For N 2 and CO 2 adsorption–desorption process, the carbon exhibits an enhanced CO 2 adsorption performance, suggesting their capture and separation capacity for CO 2 .
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2025
·
IF 9.7
Yanqiu Du,Jianxiang Shen,Haidong Li,Yang Jiang,Xuejie Liu,Wenqiang Hua,Nan Yan
Self-organization of anisotropic nanostructures into polymer/inorganic superstructures are of great research interest for various applications owing to their enhanced directional properties, such as plasmonics and catalysis. However, the controllable assembly and oriented growth of nanorods in solution without external template assistance remains a great challenge. Here, we report a facile Hofmeister-effect-based assembly strategy for fabricating ordered arrangements of polyethylene glycol-tethered gold nanorods (AuNRs@PEG) with controlled orientation and dimension. By adjusting the concentration of typical kosmotropic ions, we can precisely modulate the hydrophilic-to-hydrophobic transition of PEG ligands by the dehydration of PEG polymer ligands, enabling controlled nucleation and growth of nanorods in solution. The weak hydrophobicity of PEG ligands drives lying-down nanorods to form 2D smectic liquid crystalline phases, which serves as templates for hierarchical growth into 3D liquid crystalline phases. In contrast, the strong hydrophobicity induces standing nanorods to form hexagonally packed monolayer superlattices and face-centered cubic (FCC) superlattices. Additionally, we achieve in-situ transitions between solid–solid superstructures from smectic liquid crystalline to hexagonal packing by altering environmental conditions. This work provides a significant enhancement to the resources available for the fabrication of diverse anisotropic structures and reconfigurable materials.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2023
·
IF 6
Shibing Chen,Liangbin Lin,Sining Zheng,Hongyu Guo,Fafu Yang
The regulation of circularly polarized luminescence (CPL) signal is of great significance for practical application but rarely reported. In this work, the sign inversion of CPL based on assemblies in smectic mesophase and suspension was developed. Two stable conformers of (1S)-camphanic-decorated biscyanostilbene accounted for the formation of two different helical superstructures. Smectic mesophase was found to be a bilayer structure consisted of cis -like conformer and emitted right-handed CPL with a g lum of −0.019, while chiral assembly in suspension was made up of trans -like conformer and exhibited left-handed CPL with a g lum of 0.018. This research supplied a new strategy to tune the inverted CPL signal of homogeneous organic molecular system by simple external condition control.
研究领域:
材料科学
·
光学
·
分子化学
✓ 已验证
DOI
高影响因子
LIQUID CRYSTALS
·
2018
·
IF 2.636
Liyuan Ren,Longyan Duan,Qiang Weng,Pei Chen,Yafei Hou,Aiai Gao,Xinbing Chen,Zhongwei An
A series of 1-methyl-1H-benzimidazole-based compounds, 2-(4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-1-methyl- 1H-1,3-benzimidazole derivatives (nPPMx-M) with terminal hydrogen, methyl and nitro moieties (coded as nPPMH-M, nPPMM-M and nPPMN-M, respectively), were prepared and their structures were characterised. The compounds display enantiotropic smectic mesophases for hydrogen and methyl terminated compounds (nPPMH-M and nPPMM-M), and enantiotropic nematic mesophases for nitro terminated compounds (nPPMN-M) with short alkoxy chain below than 10 carbon atoms, where the mesophase ranges are 24–72°C and 74–104°C on heating and cooling processes for nPPMH-M, 90–119°C and 110–135°C for nPPMM-M, and 102–129°C and 113–207°C for nPPMN-M, respectively. It is noted that the compounds nPPMx-M exhibit much lower melting points and much wider mesophase range both in heating and cooling than non-1-methyl substituted analogs, which are ascribed to the disruption of hydrogen bonding among the molecules caused by methyl substitution at 1-position of benzimidazole. Meanwhile, among the compounds nPPMx-M, much wider mesophase ranges are obtained for nPPMM-M and nPPMN-M, indicating a much high mesophase stability for the compounds bearing terminal moiety (CH3 and NO2).
研究领域:
材料化学
·
物理化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）