T-型表面两亲分子形成的复杂纳米液晶超分子结构

T-型表面两亲分子是近年成功设计的一类三嵌段液晶分子之一,这类分子具有与三嵌段波拉两亲分子相反的拓扑构型。通过调节分子中各不相容嵌段的相对体积大小,能获得多种新型的二维多角形蜂窝状纳米结构,实现从分子水平上控制其自组装行为,获取超分子纳米结构的目的,为设计具有二维纳米结构的新型功能材料提供了崭新的途径。综述了这类表面两亲分子的自组装行为及它们形成的多种新型复杂液晶超分子结构。     

三嵌段波拉两亲液晶形成的二维多角形蜂窝状纳米结构

带侧链的波拉化合物是近年成功设计的一类三嵌段液晶分子,通过调节分子中各不相容嵌段相对体积的大小,获得了多种新型的二维多角形蜂窝状纳米结构,实现了从分子水平上控制其自组装行为,获取超分子纳米结构的目的,为设计具有二维纳米结构的新型功能材料提供了崭新的途径。综述了这类波拉两亲性分子的自组装行为及它们形成的多种新型复杂超分子结构。     

外场作用下嵌段共聚物微相形态的调控

嵌段共聚物可自组装形成均匀的、纳米尺度的规律图案,结合薄膜技术和器件制造技术,自组装嵌段共聚物在信息存储材料、能源器件、膜材料和流体力学等方面的潜在应用引起了人们广泛关注。介绍了通过施加外场调控嵌段共聚物微相形态的研究进展,并进行了展望。     

PEO-PPO-PEO嵌段共聚物在水溶液中的自组装行为及其应用

聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)嵌段共聚物是一类重要的非离子表面活性剂,在选择性溶剂中可以自组装成多种形貌的介观结构。对PEO-PPO-PEO嵌段共聚物在水溶液中自组装行为进行了综述,介绍了其自组装行为的实验研究技术;阐明了嵌段共聚物构型、分子量、温度、浓度、添加剂等因素对PEO-PPO-PEO嵌段共聚物聚集行为的调控和作用机理;介绍了嵌段共聚物自组装特性的热力学模型、分子模拟及计算机预报等研究方法和研究进展;重点介绍了PEO-PPO-PEO嵌段共聚物在介孔材料制备、药物载体、生物大分子分离、嵌段共聚物修饰等方面的应用。     

1,3,4-噻二唑类液晶化合物的研究进展

综述了近年来1,3,4-噻二唑类液晶化合物的研究进展,该类化合物形成棒状液晶、楔形液晶、弓形液晶、Polycatenar液晶、盘状液晶的分子结构及其自组装形成的液晶相结构。介绍了分子中末端基团、烷基链数目、刚性核长度等结构常数对液晶自组装结构的的影响。与含氧的杂环类似物1,3,4-噁二唑液晶化合物相比,1,3,4-噻二唑类液晶化合物的液晶性、光电性等更加优越。液晶方面类比表明,它具有更好的液晶性质。     

几何受限下的嵌段共聚物自组装

嵌段共聚物通过自组装可以形成特定的周期性纳米结构,然而这些有限种类的体相结构却无法有效满足实际应用中的众多需求.为丰富嵌段共聚物自组装的纳米结构库,几何受限的引入是最为有效的方法之一.几何受限改变了体相结构的平移对称性,嵌段高分子为了缓解这一破坏带来的结构受挫,从而形成更多的新相结构.本文以AB两嵌段高分子为例,从本体...     

嵌段共聚物自组装中的缺陷研究进展

嵌段共聚物自组装形成的各种有序相结构中都不可避免地包含有缺陷。由于相结构单元是高分子链段聚集而成的"域"而非传统意义上的原子,导致传统晶体中的缺陷理论无法有效解释嵌段共聚物自组装中的缺陷。因此,研究嵌段共聚物中的缺陷对软物质材料的应用具有重要意义。本文综述了嵌段共聚物体系中的几类典型缺陷的研究进展,重点介绍了我们在圆柱受限下单螺旋结构的缺陷调控以及六角排列柱状结构中5～7缺陷演化方面的研究工作。     

高分子科学 名词解释

正自增强高分子[self-reinforcing polymer]能以大分子结构或超分子结构的尺度形成增强体的高分子材料。由于它与基体的化学结构完全相同,则称这种增强方式为分子自增强。目前高分子自增强材料有两类:(1)采用棒状刚性链构造而成的自增强材料,其典型代表是主链液晶高分子;(2)     

环境响应性两亲嵌段共聚物的自组装及其药物控释研究进展

两亲嵌段共聚物形成的胶束、囊泡等典型的自组装体可作为纳米医药载体,用于药物的控释,其研究已成为当前胶化、医药和生物学科交叉领域的热点。尤其是聚乙二醇型两亲嵌段共聚物,不仅具有良好的生物相容性,而且通过适当的分子设计可形成对环境具有刺激响应的纳米载体。本文着重综述了这类两亲嵌段共聚物的自组装及其在药物控释方面的研究,总结了影响自组装的因素,并介绍了控释药物的机理。     

以三嵌段共聚物为模板介孔氧化铝的形貌控制合成

以三嵌段共聚物作为结构导向剂,采用水热法合成了片状和棒状介孔氧化铝,采用X射线衍射仪、场发射透射电子显微镜、低温氮气吸脱附实验对合成的介孔氧化铝的晶相、形貌和介孔结构进行表征。研究结果表明,三嵌段共聚物的引入能够有效调控氧化铝的形貌、介孔结构以及孔参数。三嵌段共聚物在氧化铝前驱体表面的吸附诱导了晶体的取向生长,并最终形成了棒状氧化铝。     

Lipid crystallization: from self-assembly to hierarchical and biological ordering

Lipid crystallization is ubiquitous in nature, observed in biological structures as well as in commercial products and applications. In a dehydrated state most of the lipids form well ordered crystals, whereas in an aqueous environment they self-assemble into various crystalline, liquid crystalline or sometimes macroscopically disordered phases. Lipid self-organization extends further to hierarchical levels including structured emulsions and nanostructured particles. Many consumer products including cosmetics, foods and medicines account for such lipid architectures. Cell membranes primarily consist of planar lipid bilayers; however sub-cellular biomembranes are more of a convoluted type. Some of the biological entities have lipids in truly crystalline form; yet liquid crystalline lipid phases are prevalent, in general. Crystallization of fats - triglyceride lipids - has been relatively well documented and reviewed more often, but this review features other areas where lipid organization is crucial and diverse. Some recent advances along with a few explicit examples of model lipid phases and biological evidences are also reported.     

Phase behavior of thermotropic liquid crystalline/conducting polymer blends

Summary Liquid crystalline/conducting polymer blends have been prepared. The conductingpolymer [poly(2,5-dimethoxyphenylene vinylene)] retards the liquid crystallinity of the liquid crystalline polymer (hydroxypropyl cellulose), while the liquid crystalline polymer reduces the conductivity of the conducting polymer. However, blends with 17% conducting polymer were both liquid crystalline and conductive. Dedicated to Prof. Dragutin Fleš on the occasion of his 70th birthday     

Electrooptical‐responsive microsphere with ferroelectric liquid crystalline segments

We synthesized a ferroelectric liquid crystalline monomer (4‐[4′‐(7‐octeneloxy)benzoyloxy]benzoate‐2‐methylbutyester, OBBM) possessing both carboxyl p‐benzolxybenzoate and carboxyl (s)‐(‐)‐2‐methylbutylester as a mesogenic group in its side chain. The liquid crystalline and styrene monomers were employed to make matrices of microspheres prepared by dispersion, suspension, or emulsion polymerization. In this study, we investigated, in detail, physicochemical properties, thermal responses, and electrooptical responses of the microspheres possessing liquid crystalline abilities. The ferroelectric liquid crystalline monomer OBBM had a thermotropic liquid crystalline ability, two‐phase transition temperatures, and a Smectic C* texture, which is characteristic of ferroelectric liquid crystalline substances. The microspheres prepared also exhibited a liquid crystalline ability, and the phase‐transition temperatures toward the liquid crystalline segments into the microspheres prepared by copolymerizing the liquid crystalline and styrene monomers could be decreased with increasing of the styrene monomer. Furthermore, we found that the microspheres remarkably exhibited electrooptical responses at about 8 V. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2490–2499, 2001     

液晶热性能的研究

讨论了液晶聚合物及相应的液晶单体的热性能,指出液晶聚合物的液晶温度区间总量宽于液晶单体。通常在侧链液晶聚合物中第二种单体的引 导致液晶温度区间变宽。     

Intriguing liquid crystalline behavior of liquid crystalline polyrotaxane containing azobenzene mesogens

A series of liquid crystalline polyrotaxanes containing azobenzene mesogenic moieties (AzoPR) with different length of spacer were synthesized, and the relationship between the spacer length and the liquid crystalline behavior was investigated. The molecular characterization of the AzoPR was performed with ¹H NMR, FT-IR, and gel permeation chromatography. The thermal stability was investigated via thermogravimetric analysis. Their phase structures and liquid crystalline properties were studied by differential scanning calorimetry, polarized optical microscopy and wide-angle X-ray diffraction. The experimental results suggested that AzoPR with spacer length of 2 and 4 failed to show the liquid crystalline behavior, and AzoPR with spacer length of 6 showed the columnar nematic phase. However, when the spacer length increases to 11, the columnar nematic phase formed, meanwhile, the liquid crystalline domains with high ordered structure were developed by azobenzene mesogens.     

四苯基乙烯室温液晶发光材料的制备与表征

发光液晶兼具发光性能和液晶的有序性,作为一种具有重要应用前景的功能材料而受到研究人员的广泛关注。本工作采用离子自组装法制备了一种兼具聚集诱导发光和液晶性质的四苯基乙烯衍生物(TPE-Chol)。通过吸收光谱、荧光光谱和X射线衍射等实验对TPE-Chol的光物理性质和液晶结构进行了详细研究。实验结果表明,TPE-Chol在室温状态下具有液晶结构,并且表现出典型的聚集诱导发光行为,是一种新型室温液晶发光材料,在液晶显示等领域具有潜在的应用价值。     

Synthesis,characterization, and application of semi‐interpenetrating liquid crystalline polymer networks LCP/PS

Attempts to extend the IPN technology to liquid crystalline polymer (LCP) systems have been made in search for a new approach for enhancing the compatibility of liquid crystalline polymer with engineering thermoplastics. A new type of interpenetrating polymer network based on liquid crystalline polymer : semi‐interpenetrating liquid crystalline polymer network comprising liquid crystalline polymer PET/60PHB (LCP) and crosslinked polystyrene (PS) (for short: semi‐ILCPN LCP/PS) has been successfully prepared. The compatibility and thermal properties of the semi‐ILCPN LCP/PS with different amount of crosslinking agent were investigated by FTIR, SEM, DSC, and TGA, respectively. Furthermore, the possible application of the semi‐ILCPN LCP/PS as a new kind of compatibilizer in PPO/LCP blends was also studied and discussed. Well‐compatibilized PPO/LCP composites with considerably improved mechanical properties were obtained. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1141–1150, 2000     

Development of co-continuous structure in liquid crystalline polyester

We investigated liquid crystallization of liquid crystalline polyester BB-5 during isothermal annealing by digital high-fidelity microscope and light scattering. A liquid crystalline spherical domain having a radius of micrometers appeared by annealing at around 180 °C. The domain grew dendritically in all directions. Neighboring liquid crystalline regions coalesced and then interconnected. The interconnected structure changed to a co-continuous two-phase structure with increasing ordering of the liquid crystalline phase, and the interface between the liquid crystalline phase and the isotropic phase became smoother over time. Liquid crystallization stopped before volume filling the whole space, and the liquid crystalline phase and isotropic phase coexisted. The liquid crystalline region became narrower with an increase in the temperature of the liquid crystallization. Such structural development is different from the liquid-liquid phase separation via spinodal decomposition, and it may be attributed to the segregation of non-liquid crystallizable low molecular weight molecules from the growth front by fractionation of the molecular weight distribution during the liquid crystallization in terms of the instability of the diffusion-controlled interface.     

Synthesis and characterization of optically active liquid crystalline polyacrylates containing mesogenic phenylbenzoate groups

A series of novel side chain liquid crystalline polyacrylates with pendant chiral groups were synthesized. It was found that monomers with electron releasing -OC₄H₉ terminal groups seem beneficial for the formation of liquid crystalline phases. Copolymerization of the monomers was carried out and the physical properties of the copolymers were investigated. All synthesized polymers revealed liquid crystalline phases and appeared highly thermally stable with decomposition temperatures (T_d) at 10% weight loss greater than 384 °C and about 50% weight loss occurred beyond 442 °C under nitrogen atmosphere. Two miscible chiral compounds were also synthesized and used as chiral dopants to induce cholesteric liquid crystalline phases of polymers. Liquid crystalline phases of the polymers were investigated using DSC and XRD, and confirmed with POM technique. The optical properties of the induced cholesteric liquid crystalline polymers were investigated using UV-vis spectrometer. The appearance and the color variation of the polymer films before and after UV irradiation were also investigated. Typical helical morphology of the cholesteric liquid crystalline film was analyzed by SEM technique.     

联苯类液晶环氧树脂的合成研究

采用二步法合成液晶环氧树脂,首先合成含有刚性棒状介晶基元的联苯类环氧预聚体,将介晶基团通过共价键接入环氧树脂网络,再通过固化反应得到高度交联的液晶热固性树脂.探讨了固化剂及碱的用量、反应温度等对合成液晶的影响,利用IR与DSC等分析手段对合成的单官能团液晶环氧化合物（SCEP）和液晶环氧树脂进行结构表征,结果表明合成的物质为低分子液晶环氧化合物.