Nano-Segregation and Directed Self-Assembly in the Formation of Functional Liquid Crystals

It is often a question that is asked: “How can you predict from the molecular architecture of a material the structure of the condensed phases it forms, and what properties would you expect the phase to exhibit?” For liquid crystals, knowing how to design materials for particular applications requires precision molecular engineering. In this article we examine how molecular topology and interactions influence phase formation and report on material design.     

溶致液晶模板法制备CuO纳米粒子

利用溶致液晶的有序结构特性,在不同的介观空间内组装不同性质的纳米粒子,从而获得具有特定功能的纳米材料。本文研究内容主要包括：利用非离子表面活性剂Brij58制备反六角相溶致液晶,以该反六角液晶为模板,以Cu（NO3）2水溶液代替体系中的水相制备铜纳米粒子。利用偏光显微镜、X射线衍射和粒度分析仪对样品进行表征。实验表明,不同浓度下形成不同相的液晶,在400℃下煅烧可得到CuO纳米材料。     

Synthesis of Gold Nanoplates in Lecithin Lamellar Liquid Crystals

Gold nanoplates mixed with spherical nanoparticles were prepared in lecithin lamellar liquid crystals containing non‐ionic surfactants as reductant. The effects of the concentrations of surfactants, reactants and salt on the formation of the nano‐products are discussed. The selective adsorption of lecithin headgroups on metal surfaces plays an important role in nanoplate formation. However, this effect is weakened by the large volume of the headgroups and only a few plates can be observed. Using biological liquid crystals as a template to synthesize the anisotropic noble metal nanoparticles will be helpful for better understanding the formation of nanostructures with controllable morphologies in biomimetic systems.     

Microsegregation: From Basic Concepts to Complexity in Liquid Crystal Self-Assembly

This review is focused on the basic concepts of microsegregation and a fundamental understanding of the formation of positionally ordered LC phases based on micro- and nanophases, interaction parameters and interfaces. Selected examples were chosen from the actual literature to illustrate the concepts. Microsegregation is the basis of classical LC phases and cybotaxis, and most importantly, it paves the way to a huge number of new LC phases. Beside the distinct modes of micellar packing motifs and liquid quasicrystals formed by self-assembly of dendritic molecules, attention is also focused on the specific effects of rigid anisometric units and polyphilicity. Honeycomb LC phases, vesicular LC phases and mesophases with 3D-lattices lead to enhanced complexity of LC self-assembly.     

胆甾型液晶的合成及显色示温液晶组成

合成并表征了两种对正烷氧基苯甲酸胆甾醇酯液晶 ,并用于显色示温混合液晶的配制。通过胆甾型液晶的选择及不同含量的调配 ,获得变色温度范围在 1 0～ 40°C、色泽鲜艳、温度感应灵敏、变色可逆的胆甾型混合液晶组成。讨论了混合液晶组成对显色示温的影响     

Improvement of the Performance of Liquid Crystal Displays by Doping with Supramolecule-Protected Metal Nanoparticles

Metal nanoparticles are now creating a new class of materials that are different from either conventional bulk materials or atoms, giving one of the smallest building blocks of matter. Metal nanoparticles have various properties based on high surface area and quantum size effects. Here we focus on the application of metal nanoparticles to liquid crystal displays, which is providing a new field in science and technology. The doping of nanoparticles into liquid crystal materials induces the modification of almost all of the physical properties of the liquid crystal, causing a reduction in the response time of liquid crystal displays. These techniques may be an alternative approach for improving the properties of liquid crystals other than chemical synthesis.     

侧向氟代四环类液晶单体的合成

以4-(反式-4-烷基环己基)-2-氟苯硼酸和卤代苯为起始原料,采用Suzuki偶联反应合成了2个系列15个侧向氟取代双烷基环己基联苯类液晶,采用1H NMR、IR和MS对其结构进行了确证。讨论了不同催化剂、反应底物量以及不同的碱对反应结果的影响,结果表明:在强碱碳酸钾作用下,Pd(PPh3)4作催化剂、4-(反式-4-烷基环己基)-2-氟代苯硼酸∶卤代苯(摩尔比)=1.1∶1时,反应选择性和收率较高,产品收率最高达89%。     

利用格氏反应制备多氟乙烷类液晶的新方法

以4-氯甲基-4′-正烷基-1,1-双环己烷与3,4,5-三氟苯腈为原料,通过格氏反应合成中间体酮,再经黄鸣龙还原得多氟乙烷类液晶化合物,总收率≥160％。     

新型苯酯苯类液晶化合物的合成与表征

以酒石酸为中心合成一种苯酯苯类高分子液晶化合物,2,3-二烯丙氧基苯甲酰氧基丁二酸对乙氧基苯甲酸对苯二酚酯(M1)。采用红外光谱仪(FT-IR)、差示扫描量热仪(DSC)、及偏光显微镜(POM)等技术进行了结构表征。实验结果表明,单体M1为热致互变向列液晶,升温过程和降温过程中均呈现纹影织构,相转变是可逆的。     

DNA-Functionalized Carbon Nanotubes: Synthesis,Self-Assembly,and Applications

Carbon nanotubes (CNTs) possess outstanding structural, mechanical, and electronic properties. Nevertheless, to achieve the full potential of CNTs, researchers must develop new purification methodologies or improvements in the existing purification and separation protocols, design and study novel functionalization chemistries that result in increased solubility of the CNTs without altering their properties, and devise a straightforward methodology for the attachment of aligned CNTs on solid substrates. To address these challenges, our group has studied the chemical functionalization of CNTs with deoxyribonucleic acid (DNA)—by covalent and non-covalent approaches—in combination with the self-assembling technique. In this short review, we will present an overview of DNA-functionalized CNTs, focusing on the main findings of our group, and the application of the DNA-CNT complexes as electrochemical biosensors.     

高效酰化催化法合成新型胆甾醇酯液晶

采用高效酰化催化法和酰氯化法分别合成了燕尾型胆甾醇酯和对称脂肪族二羧酸胆甾醇酯两类衍生物样品。采用元素分析、红外光谱、DSC、热台偏光显微镜对样品的化学结构和液晶性能进行了表征。3个对称脂肪族二羧酸胆甾醇酯样品均为胆甾型液晶,而燕尾型的支链结构对胆甾醇酯液晶的形成具有不利的影响。两种合成胆甾醇酯的酰化方法经过对比表明,高效酰化法具有反应条件温和、副反应小、不破坏反应物、产物易分离、产率高等优点,可作为胆甾醇酯液晶合成的首选方法。     

二苯乙炔类液晶的合成和相变研究

以碘代烷氧基苯与烷基苯乙炔为中间体，采用为催化剂偶联的方法合成了二苯乙炔类液晶化合物，通过对这类液晶化合物的相变研究，证实这类液晶化合物具有优良的液晶性能。     

我国手性液晶的研究进展与应用

阐述了手性液晶的结构和分类,介绍了近年来国内手性液晶的合成与研究进展情况,并着重讨论了胆甾相手性液晶的热色效应及其作为手性添加剂在显示领域的应用以及铁电液晶的非线性光学效应.     

Synthesis,Properties, and Selected Technical Applications of Magnesium Oxide Nanoparticles: A Review

In the last few decades, there has been a trend involving the use of nanoscale fillers in a variety of applications. Significant improvements have been achieved in the areas of their preparation and further applications (e.g., in industry, agriculture, and medicine). One of these promising materials is magnesium oxide (MgO), the unique properties of which make it a suitable candidate for use in a wide range of applications. Generally, MgO is a white, hygroscopic solid mineral, and its lattice consists of Mg2+ ions and O2− ions. Nanostructured MgO can be prepared through different chemical (bottom-up approach) or physical (top-down approach) routes. The required resultant properties (e.g., bandgap, crystallite size, and shape) can be achieved depending on the reaction conditions, basic starting materials, or their concentrations. In addition to its unique material properties, MgO is also potentially of interest due to its nontoxicity and environmental friendliness, which allow it to be widely used in medicine and biotechnological applications.     

Conifer-Derived Metallic Nanoparticles: Green Synthesis and Biological Applications

The use of metallic nanoparticles in engineering and biomedicine disciplines has gained considerable attention. Scientists are exploring new synthesis protocols of these substances considering their small size and lucrative antimicrobial potential. Among the most economical techniques of synthesis of metallic nanoparticles via chemical routes, which includes the use of chemicals as metal reducing agents, is considered to generate nanoparticles possessing toxicity and biological risk. This limitation of chemically synthesized nanoparticles has engendered the exploration for the ecofriendly synthesis process. Biological or green synthesis approaches have emerged as an effective solution to address the limitations of conventionally synthesized nanoparticles. Nanoparticles synthesized via biological entities obtained from plant extracts exhibit superior effect in comparison to chemical methods. Recently, conifer extracts have been found to be effective in synthesizing metallic nanoparticles through a highly regulated process. The current review highlights the importance of conifers and its extracts in synthesis of metallic nanoparticles. It also discusses the different applications of the conifer extract mediated metallic nanoparticles.     

含氟的反式-1,4-二芳基环己烷类液晶合成及性能研究

优化合成一系列含氟反式-1,4-二芳基环己烷类液晶化合物,气相色谱测定含量＞99.8%,收率达67.0%,并对其性能进行了研究.     

A New Series of Kinked Liquid Crystals: 2-(6-Alkoxynaphthalen-2-yl)-6-methoxyquinolines

A new series of 2-(6-alkoxynaphthalen-2-yl)-6-methoxyquinolines (nO-NpQOMe, n = 3–8) liquid crystal compounds, a linear molecular structure with two kinks, were synthesized using a short two-step reaction with overall yields between 43% and 58%. Spectral analyses were in accord with the expected structures. Thermotropic behavior of these liquid crystal compounds were investigated using polarized optical microscopy and differential scanning calorimetry. All compounds exhibited purely enantiotropic nematic phase at the medium–high temperature range of 162.4–234.2 °C. However, short ranges of nematic phase, 20.5–16.6 °C at heating and 46.7–37.0 °C at cooling, were observed in these linear liquid-crystalline compounds with two kinks.     

Self-Assembly of pH-Labile Polymer Nanoparticles for Paclitaxel Prodrug Delivery: Formulation,Characterization, and Evaluation

The efficacy of paclitaxel (PTX) is limited due to its poor solubility, poor bioavailability, and acquired drug resistance mechanisms. Designing paclitaxel prodrugs can improve its anticancer activity and enable formulation of nanoparticles. Overall, the aim of this work is to improve the potency of paclitaxel with prodrug synthesis, nanoparticle formation, and synergistic formulation with lapatinib. Specifically, we improve potency of paclitaxel by conjugating it to α-tocopherol (vitamin E) to produce a hydrophobic prodrug (Pro); this increase in potency is indicated by the 8-fold decrease in half maximal inhibitory concentration (IC₅₀) concentration in ovarian cancer cell line, OVCA-432, used as a model system. The efficacy of the paclitaxel prodrug was further enhanced by encapsulation into pH-labile nanoparticles using Flash NanoPrecipitation (FNP), a rapid, polymer directed self-assembly method. There was an 1100-fold decrease in IC₅₀ concentration upon formulating the prodrug into nanoparticles. Notably, the prodrug formulations were 5-fold more potent than paclitaxel nanoparticles. Finally, the cytotoxic effects were further enhanced by co-encapsulating the prodrug with lapatinib (LAP). Formulating the drug combination resulted in synergistic interactions as indicated by the combination index (CI) of 0.51. Overall, these results demonstrate this prodrug combined with nanoparticle formulation and combination therapy is a promising approach for enhancing paclitaxel potency.     

Mechanisms of Orientation of Polymer Liquid Crystals (PLCs) in External Fields

Abstract

We analyze existing theories of behavior of polymer liquid crystals (PLCs) in external fields such as electric or magnetic. Against this background, we recall a fairly general theory of PLCs [77] and extend it to include effects of the external fields. We consider in particular phase transitions that PLCs undergo. In some cases the changes are qualitative only. However, we also observe significant quantitative modifications of phases caused by the presence of the fields.