Synthesis and characterization of liquid crystalline ionomers with polymethylhydrosiloxane main-chain- and side-chain-containing sulfonic acid groups

A novel thermotropic side-chain liquid crystalline ionomer (LCI) containing sulfonic acid groups on the side-chain was synthesized by graft copolymerization of mesogenic monomer 4-allyloxy-benzoxy-4′-methoxyphenyl (ABM) and nonemesogenic monomer 4-allyloxy-azobenzene sulfonic acid (AABS) upon polymethylhydrosiloxane (PMHS). The chemical structures of the polymers were confirmed by IR spectroscopy. DSC and TGA were used to measure the thermal properties of those polymers and the mesogenic properties were characterized by polarized optical micrography (POM), DSC, and WAXD. The clearing point temperature (T_c) of these liquid crystalline ionomers was enhanced 50–60°C compared with the polymer without ionic groups. The LCIs exhibit a broad smectic mesogenic region of 80–90°C; the thermal stability below 200°C of the polymers decreases with increasing sulfonic acid concentration. The inherent viscosity of 0.5% solutions decreased with increasing sulfonic acid concentration in the polymer chains. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1555–1561, 1998     

Synthesis,characterization, and thermomechanical properties of liquid crystalline epoxy resin containing ketone mesogen

This study focuses on the synthesis of a novel liquid crystalline epoxy resin (LCER) based on ketone mesogenic group. The chemical structure, melting range, and liquid‐crystalline phase transition behavior of the LCER were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, mass spectroscopy, differential scanning calorimetry (DSC), and polarized optical microscopy (POM). Two endothermal peaks and one exothermal peak appeared in the DSC curves. A birefringent liquid crystalline texture was observed with POM during heating. The curing reaction of the LCER was monitored by DSC using diaminodipheylmethane (DDM) and diaminodiphenylsulfone (DDS) as curing agents, respectively. The results showed that the curing reaction of LCER/DDM proceeded faster than that of LCER/DDS in the initial stage. Birefringence was observed with POM during the curing processes. The results of thermomechanical properties showed that the glass transition temperatures of the cured LCERs were higher than 230°C, and that the LCER crosslinked networks were thermally stable up to 360°C. The LCER crosslinked networks showed much higher glass transition temperature, storage modulus, and thermal conductivity, and a lower coefficient of thermal expansion both in the glassy region and the rubbery region compared to those of a common epoxy resin (diglycidyl ether of bisphenol A). POLYM. ENG. SCI., 57:424–431, 2017. © 2016 Society of Plastics Engineers     

含2种介晶基元的液晶弹性体合成与性能研究

合成了一种向列液晶单体（M1）和一种新型手液晶交联单体（M2）,与含氢聚硅氧烷（PM-HS）接枝共聚。交联剂的摩尔分数从0－20%,得到了一系列侧链液晶弹性体P1－P7。通过差式扫描量热仪（DSC）、偏光显微镜（POM）和X-射线分析等手段对聚合物的结构、液晶性能及热性能进行了表征。结果表明,聚合物P1为向列液晶聚合物,P2－P6为胆甾液晶弹性体,P7没有液晶性。随着交联单体M2摩尔分数在体系中的增加,聚合物的玻璃化转变温度（Tg）、清亮点（Ti）和介晶范围逐渐降低。     

Effect of the lateral substituent on the mesomorphic behavior of side-chain liquid-crystalline polymers containing a Schiff base ester

New polymerizable macromers containing a Schiff base ester linkage have been synthesized. These macromers were used to synthesize side-chain liquid-crystalline polymers (SCLCPs) by radical polymerization. The chemical structures of the macromers and polymers were characterized by spectroscopic techniques (FTIR, ¹H NMR, and ¹³C NMR). The mesomorphic properties of the macromers as well as the polymers were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) and confirmed by powder X-ray diffraction (PXRD). POM and DSC studies revealed that all of the macromers and polymers showed liquid crystal behavior, with their nematic phases occurring in different mesophase ranges. The macromer without a lateral unit in the mesogen (M1) showed a thermal transition at a relatively high temperature (181.4 °C), whereas the macromer with a lateral unit in the mesogen (M2) showed a thermal transition at a relatively low temperature (101.8 °C). The SCLCP from macromer M1 (HPM1) also showed a comparatively high-temperature thermal transition compared to that of the polymer from macromer M2 (HPM2). The thermal properties of the polymers were studied by thermogravimetric analysis (TGA). The polymer from the macromer with a lateral unit in the mesogen (M2) showed higher thermal stability than the polymer from the macromer without a lateral unit (M1).     

环氧液晶对木质素/聚丙烯复合材料结构和性能影响

以4,4'-二(β-羟乙氧基)联苯(BP2)、环氧氯丙烷及对苯二甲酰氯等为原料,通过取代反应合成一种小分子的环氧液晶(LCEP),将该LCEP与木质素(lignin)/聚丙烯(PP)进行共混改性,采用FT-IR、DSC、POM及TGA等对LCEP结构和液晶相转变行为进行了表征,并研究了LCEP含量对Lignin/PP复合材料物理力学性能和热性能的影响。利用SEM观察了复合材料断裂形貌,探讨其增韧增强机理。结果表明:加入4%的LCEP聚丙烯/木质素复合材料的综合性能最好,其冲击强度、弯曲强度和弯曲模量较未改性前分别提高了38.6%、30.5%和20%,热稳定性、结晶性和结晶速率也有明显提高。     

Synthesis and characterization of chiral side‐chain liquid‐crystalline polymer containing menthol ester

The synthesis of new chiral side‐chain liquid‐crystalline polysiloxanes containing p‐(allyoxy)benzoxy‐p‐chlorophenyl (ABCH) as mesogenic units and undecylenic acid menthol ester (UM) as chiral nonmesogenic units is presented. The chemical structures of monomers and polymers are confirmed by IR spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are used to measure thermal properties of those polymers. Mesogenic properties are characterized by polarized optical microscope (POM), DSC, and small‐angle X‐ray diffraction. Analytic results revealed that polymers P₀–P₆ are thermotropic liquid‐crystalline polymers with low glass transition; Polymers P₂–P₆ exhibit chiral smectic liquid‐crystalline properties with marble texture, optical rotation, and a sharp reflection at low angles in X‐ray diffraction; polymers P₀, P₁ only exhibit smectic liquid‐crystalline properties without chirality; and P₇ only exhibits chirality without liquid‐crystalline properties. All the polymers exhibit good thermal stability with temperature of 5% mass loss over 297°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2845–2851, 2003     

环氧树脂/环氧液晶/蒙脱土纳米复合材料研究

采用液晶环氧预聚物(PHQEP)与有机蒙脱土(OMMT)共混改性环氧树脂制备三元共混体系的环氧基复合材料。用X射线衍射法(XRD)测试了有机化蒙脱土在被插层前后片层间距的变化,通过DSC、TGA及SEM等对PHQEP/OMMT增韧改性环氧树脂固化体系的力学性能,热性能及微观相态结构进行了研究。结果表明:当PHQEP质量分数为5%,添加1.5%的有机蒙脱土可以使环氧树脂的冲击强度达到最大值23.43 kJ/m2,比纯环氧树脂提高2倍左右,玻璃化转变温度及5%热分解温度比纯环氧树脂分别高出15℃和27℃。PHQEP与OMMT的加入使纳米复合材料的力学性能和热性能得到明显提高。     

Synthesis and characterization of main-chain liquid crystalline copolyesters containing phosphaphenanthrene side-groups

A series of thermotropic main-chain liquid crystalline copolyesters P1-P5 containing 2-(6-oxide-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-dihydroxyphenylene (ODOPB) as non-mesogenic unit and 4,4′-dihydroxybiphenyl (DB) as mesogenic unit were prepared by polycondensation with sebacoyl chloride. The thermal and mesogenic properties were characterized by differential scanning calorimetry (DSC), polarizing optical micrography (POM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). It was found that introducing of ODOPB into polyester decreased the melting temperature (Tm) and the isotropic temperature (Ti). The copolyesters P1-P5 exhibited mesomorphic properties even when the molar ratio of the non-mesogenic monomer ODOPB to mesogenic monomer DB reached 6:4 in feed. For explaining the effect of DOPO group on the mesomorphic properties, the X-ray diffraction analysis of a low molecular weight modal compound containing ODOPB was carried out and the results show that the DOPO side-group is parallel with the most-adjacent benzene ring in the main-chain, which reveals the small effect of ODOPB on the mesogenic structure of polyesters. The thermal analysis showed that the incorporation of phosphorus-containing moieties increase the residual char of the formed liquid crystalline polymers. The thermal stability, however, decreases because the OP-O bond is less stable than the common C-C bond.     

Self-assembly of ABC coil-rod-coil triblock molecules with perforated lamellar mesophases

The synthesis and characterization of ABC coil-rod-coil triblock (monomer) and ABCBA coil-rod-coil-rod-coil triblock dimer (dimer) molecules of docosyl 4′-[4′-[methyloxypoly(ethyleneoxy)ethyloxy]-4-biphenylcarboxyloxy]-4-biphenyl carboxylate with poly(ethylene oxide) (PEO) coil are described. The self-assembling behavior of triblock molecules is characterized by a combination of techniques consisting of differential scanning calorimetry (DSC), thermal polarized optical microscopy (POM), and X-ray diffraction (XRD) measurement. Monomer and dimer self-assemble into three lamellar crystalline phases (k₁, k₂, and k₃) and 3D-hexagonally perforated lamellar (HPL) and 2D-hexagonal columnar (col) liquid crystalline phases as temperature increases. In addition to the phases exhibited by monomer, dimer shows 3D-tetragonally perforated lamellar (TPL) and spherical micellar (M) liquid crystalline phases. These results demonstrate that simple dimerization of coil-rod-coil molecule by connecting PEO block induces 3D-tetragonally perforated lamellar and spherical micellar mesophases.     

大规模集成电路封装用联苯型环氧树脂的制备及其结构与性能

采用３,3′,5,5′-四甲基-4,4′-联苯二酚与环氧氯丙烷在18-冠-6-醚(CE18)为相转移催化剂作用下,利用两步加碱法合成了联苯型环氧树脂（TMBP）,在反应温度为80 ℃、反应时间为8 h、NaOH用量为0.2 mol时,产率达83 ％。用核磁共振、红外光谱、X射线衍射、热台偏光显微镜和DSC对所制备的产物进行了结构表征。结果表明,合成的产物为TMBP,具有良好的结晶性,熔点为107.8 ℃,在冷却过程中出现液晶态。TMBP熔融黏度极低（0.02 Paos,150 ℃）,用TMBP与酚醛环氧树脂（ECN）共混,可降低体系的黏度,从而提高硅微粉的填充量和大规模集成电路封装材料的流动性。     

表面结构不同的纳米二氧化硅原位改性聚甲醛的研究

分别选用环氧基纳米二氧化硅（SiO2）(RNSE)和甲基纳米SiO2(DNS)为填料,通过原位聚合法制备了聚甲醛(POM)/纳米SiO2复合材料,采用场发射扫描电子显微镜、热重分析仪、差示扫描量热仪、偏光显微镜和X射线衍射仪对所得复合材料的结构、热稳定性和结晶行为进行了研究。结果表明,纳米SiO2的用量和表面结构不仅影响了其在复合材料中的分散性,而且对复合材料的热稳定性和结晶行为影响显著;当RNSE的用量少于1 %（质量分数,下同）时,其在POM基体中具有较好的分散性,且相对于DNS,RNSE的分散性更好;纳米SiO2加速了POM结晶,减小了球晶尺寸,提高了结晶度,而且RNSE比DNS对POM的结晶具有更显著的促进作用,但纳米SiO2没有改变POM的晶体结构;引入纳米SiO2降低了POM的热稳定性。     

Curing and Thermal Properties of PEPEB Liquid Crystalline Diepoxide/Aromatic Diamine

The liquid crystalline epoxy resin p-phenylene di[4-2-(2,3-epoxypropyl)ethoxy] benzoate (PEPEB) was synthesized. The curing behavior of the liquid crystalline epoxy resin (LCER) with 4,4-diaminodiphenylmethane (DDM) was studied by fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and torsional braid analysis (TBA). Morphology of curing product was observed by polarized optical microscopy (POM) at different temperatures. Nonisothermal curing kinetics of this system were investigated by DSC. Results show that the PEPEB has a smectic liquid crystalline structure, and the melting point, T _m, is 119°C, the clearing point is 184°C. The cured-system's gel point, T _I , is 83.5°C; cure temperature, T _P , is 111.6°C; and the disposal temperature, T _f , is 145.8°C; activation energy of curing reaction is 4.84 KJ/mol. Observation by POM shows that with the upgrade of initial curing temperature, the filament structure of this system transferred from anisotropy to isotropy.     

热致性液晶固化剂增韧环氧树脂的研究

合成了一种环氧树脂的热致性液晶固化剂,利用红外光谱、偏光显微镜（POM）、差热分析仪（DSC）、元素分析等手段确认其结构。将此液晶固化剂加入环氧树脂／二氨基二苯砜（DDS）固化体系中,测试了固化物的力学性能,并用热重量分析仪（TG）、DSC测试了固化物的玻璃化转变（Tg)和热失重温度（Td),用偏光显微镜（POM）以不同配比的环氧树脂／液晶固化剂体系的固化样品形貌进行观察。结果表明：加入不到3％的液晶固化剂,可以使环氧固化物的拉伸强度提高50％,冲击强度提高一倍,Tg和Td明显提高,偏光显微镜照片表明液晶固化剂的加入使固体体系出现了相分离。     

Polyacetylenes bearing mesogenic side groups: synthesis and properties. Part 3. Influence of flexible spacer length and tail functionality

We report on the synthesis of some novel liquid crystalline polyacetylenes derived from monosubstituted acetylenic monomers where the acetylenic moiety is linked through a short spacer (one or three methylene units and an ether bridge) to a biphenyl mesogenic core. The influence of length and functionality of the terminal groups on the thermal behaviour and on the nature of the mesophases is discussed. All the monomers show liquid crystalline behaviour. Polymerisations are carried out in solution with typical metathesis catalysts based on Mo and W and yield polyacetylenes with fairly high MW soluble in common organic solvents. Polymers are fully characterised by GPC, FT-IR, and ¹H NMR techniques; their thermal and morphological behaviour has been studied by TGA, DSC, POM and X-ray diffraction experiments.     

Protective Effects of Hydrogen Sulfide in Hypoxic Human Umbilical Vein Endothelial Cells: A Possible Mitochondria-Dependent Pathway

The aim of the study was to investigate the protective effects of sodium hydrosulfide (NaHS), a H₂S donor, against hypoxia-induced injury in human umbilical vein endothelial cells (HUVECs) and also to look into the possible mechanisms by which H₂S exerts this protective effect. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and scratch wound healing assay were chosen to measure the cell viability and migration-promoting effects. The fluorescent probe, DCFH-DA and 5,5′,6,6′-Tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide (JC-1) were applied to detect the reactive oxygen species (ROS) level and mitochondrial membrane potential (ΔΨ_m). Furthermore, western blots were used to measure the expressions of the apoptosis-related proteins. Under hypoxic conditions, 300 μM and 600 μM of H₂S could protect HUVECs against hypoxia-induced injury, as determined by MTT assay. Following the treatment of 60 μM NaHS for 18 h, scratch wound healing assays indicated that the scratch became much narrower than control group. After treatment with 60 μM, 120 μM, and 600 μM NaHS, and hypoxia for 30 min, flow cytometry demonstrated that the ROS concentrations decreased to 95.08% ± 5.52%, 73.14% ± 3.36%, and 73.51% ± 3.05%, respectively, compared with the control group. In addition, the JC-1 assay showed NaHS had a protective effect on mitochondria damage. Additionally, NaHS increased Bcl-2 expression and decreased the expression of Bax, Caspase-3 and Caspase-9 in a dose-dependent way. Our results suggest that H₂S can protect endothelial cells and promote migration under hypoxic condition in HUVECs. These effects are partially associated with the preservation of mitochondrial function mediated by regulating the mitochondrial-dependent apoptotic pathway.     

Synthesis of LC p-Biphenyl di{4-[2-(2,3-epoxypropyl)ethoxy] benzoate} and Curing Kinetics with Succinic Anhydride

A liquid crystalline (LC) diepoxide of p-biphenyl di{4-[2-(2,3-epoxypropyl)ethoxy] benzoate} (p-BPEPEB) was synthesized from allyl 2-hydroxyethyl ether, 4-hydroxy ethyl benzoate, 4,4-biphenol and m-chloroperoxybenzoic acid (MCPBA). Its structure was characterized by FTIR, ¹HNMR. The thermal properties and liquid crystalline behavior were investigated by using DSC, POM and XRD. The results show that the p-BPEPEB has a smectic liquid crystalline structure, and the melting point is 155°C. The curing kinetics of p-BPEPEB with succinic anhydride was investigated by nonisothermal DSC method. The results show that the cured system's initial temperature T_i is 90.8°C; peak temperature T_p is 128.4°C and finishing temperature T_f is 144.7°C. The apparent activation energy Ea is 213.69 KJ/mol, and with the increase of conversion rate the value reduces.     

联苯型环氧液晶改性环氧塑封材料的性能研究

合成了一种端环氧基的联苯型液晶(LCEP),采用红外光谱(FT-IR)、示差扫描量热法(DSC)和偏光显微镜(POM)对其结构和热性能进行了分析,并以LCEP、环氧树脂、无机粉体(Al2O3和AlN)制备了环氧塑封料,通过对其力学性能、导热系数、线膨胀系数、电性能及热稳定性的测试研究了LCEP及无机粉体的加入对塑封料性能的影响。结果表明:加入LCEP后,塑封材料的冲击性能、弯曲性能均有所提高。同时,塑封料的导热系数、介电常数、热分解温度随着Al2O3、AlN含量的增加而增大,LCEP对于提高材料的导热性和热稳定性也有一定贡献。而线膨胀系数、介电损耗随着Al2O3和AlN含量的增加而降低,加入LCEP后塑封料的线膨胀系数略有降低。     

Copper(II) Complexes Containing Natural Flavonoid Pomiferin Show Considerable In Vitro Cytotoxicity and Anti-inflammatory Effects

A series of new heteroleptic copper(II) complexes of the composition [Cu(L)(bpy)]NO₃·2MeOH (1), [Cu(L)(dimebpy)]NO₃·2H₂O (2), [Cu(L)(phen)]NO₃·2MeOH (3), [Cu(L)(bphen)]NO₃·MeOH (4), [Cu(L)(dppz)]NO₃·MeOH (5) was prepared, where HL = 3-(3,4-dihydroxyphenyl)-5-hydroxy-8,8-dimethyl-6-(3-methylbut-2-ene-1-yl)-4H,8H-benzo[1,2-b:3,4-b′]dipyran-4-one, (pomiferin) and bpy = 2,2′-bipyridine, dimebpy = 4,4′-dimethyl-2,2′-bipyridine, phen = 1,10-phenanthroline, bphen = 4,7-diphenyl-1,10-phenanthroline, and dppz = dipyrido[3,2-a:2′,3′-c]phenazine. The complexes were characterized using elemental analysis, infrared and UV/Vis spectroscopies, mass spectrometry, thermal analysis and conductivity measurements. The in vitro cytotoxicity, screened against eight human cancer cell lines (breast adenocarcinoma (MCF-7), osteosarcoma (HOS), lung adenocarcinoma (A549), prostate adenocarcinoma (PC-3), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), colorectal adenocarcinoma (Caco-2) and monocytic leukemia (THP-1), revealed the complexes as effective antiproliferative agents, with the IC₅₀ values of 2.2–13.0 μM for the best performing complexes 3 and 5. All the complexes 1–5 showed the best activity against the A2780R cells (IC₅₀ = 2.2–6.6 μM), and moreover, the complexes demonstrated relatively low toxicity on healthy human hepatocytes, with IC₅₀ > 100 μM. The complexes were evaluated by the Annexin V/propidium iodide apoptosis assay, induction of cell cycle modifications in A2780 cells, production of reactive oxygen species (ROS), perturbation of mitochondrial membrane potential, inhibition of apoptosis and inflammation-related signaling pathways (NF-κB/AP-1 activity, NF-κB translocation, TNF-α secretion), and tested for nuclease mimicking activity. The obtained results revealed the corresponding complexes to be effective antiproliferative and anti-inflammatory agents.     

LCP与PA66共混物的DSC分析与相容性研究

用溶液共混的方法制备热致聚酯酰胺液晶（LCP）和尼龙66（PA－66）共混物,用DSC、POM、WAXD等手段对共混物进行了表征。DSC和POM研究结果表明,LCP与PA－66之间有较好的相容性,LCP能在PA－66中较均匀分散,LCP的加入影响了PA－66的熔融和结晶行为,少量的LCP有利于PA－66的结晶,WAXD结果表明,LCP掺入了PA－66的结晶过程、形成共晶。     

Human DDX3X Unwinds Japanese Encephalitis and Zika Viral 5′ Terminal Regions

Flavivirus genus includes many deadly viruses such as the Japanese encephalitis virus (JEV) and Zika virus (ZIKV). The 5′ terminal regions (TR) of flaviviruses interact with human proteins and such interactions are critical for viral replication. One of the human proteins identified to interact with the 5′ TR of JEV is the DEAD-box helicase, DDX3X. In this study, we in vitro transcribed the 5′ TR of JEV and demonstrated its direct interaction with recombinant DDX3X (K_d of 1.66 ± 0.21 µM) using microscale thermophoresis (MST). Due to the proposed structural similarities of 5′ and 3′ TRs of flaviviruses, we investigated if the ZIKV 5′ TR could also interact with human DDX3X. Our MST studies suggested that DDX3X recognizes ZIKV 5′ TR with a K_d of 7.05 ± 0.75 µM. Next, we performed helicase assays that suggested that the binding of DDX3X leads to the unwinding of JEV and ZIKV 5′ TRs. Overall, our data indicate, for the first time, that DDX3X can directly bind and unwind in vitro transcribed flaviviral TRs. In summary, our work indicates that DDX3X could be further explored as a therapeutic target to inhibit Flaviviral replication