乙基纤维素／丙烯酸体系的液晶相行为研究

利用阿贝折光仪、偏光显微镜、小角光散射仪等手段系统地考察了乙基纤维素／丙烯酸（ＥＣ／ＡＡ）体系的各种织构形式和光散射图形，并对其内部结构进行了分析。     

染料掺杂胆甾相液晶激光器的光子态密度研究

从光子态密度理论出发,数值模拟在染料掺杂胆甾相液晶中光子态密度随波长分布图,结果显示,在禁带边缘532nm、592nm处光子态密度急剧升高。制作了染料掺杂胆甾相液晶激光器,实验测得光子禁带的短波与长波边沿分别为557nm、594nm。在全固态532nm脉冲激光器45度角泵浦下,得到波长为573nm激光辐射,实验结果与数值模拟结果基本一致。     

手性E型胆甾相液晶薄膜的制备与偏振特性研究

制作出一种厚度为30μm的手性E型胆甾相液晶薄膜,通过原子力显微镜测试显示其螺距为364nm。使用He-Ne激光对其出射光的偏振特性及左右圆偏振光透射特性进行测试,结果表明手性E型胆甾相液晶表现出较强的左圆偏振光透射特性,其左右圆偏振光透射比为1∶0.4。     

Effect of nonmesogenic crosslinking units on the mesogenic properties of side‐chain cholesteric liquid crystalline elastomers

A series of cyclosiloxane‐based cholesteric liquid crystalline elastomers were synthesized by using cholest‐5‐en‐3‐ol(3β)‐4‐(2‐propenyloxy)benzoate and a soft nonmesogenic crosslinking agent, acryloyl‐hexyl acrylate. The polymers were prepared in a one‐step reaction with the crosslinking contents ranging between 0 and 5.6 weight %. The effective crosslink density (M_c) was determined by swelling experiments employing Flory–Rehner models. All the polymers exhibited thermotropic LC properties and revealed a cholesteric phase. With increase of the crosslinking component in the polymers, the melting behavior disappeared and the enthalpy of transition decreased. But the temperature of glass transition and clear point changed little and did not show uptrend or downtrend. Reflection spectra of the cholesteric mesophase of the polymers showed that the reflected wavelength became broad and shifted to long wavelength with increase of the soft crosslinking component in the polymer systems. All these results originate from the effect of the soft nonmesogenic chemical crosslinking. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 625–631, 2005     

Synthesis and lyotropic behavior of mesogen‐linked cellulose acetates

Three aromatic (p‐carboxyl phenyl) esters, 4‐(benzoyloxy) benzoic acid, 4‐(4′‐methylbenzoyloxy) benzoic acid, and 4‐(4′‐chlorobenzoyloxy) benzoic acid, were synthesized and they showed nematic monotropic or thermotropic behavior. The mesogen‐linked cellulose acetates were first prepared by the reaction of aromatic (p‐carboxyl phenyl) esters with cellulose acetate through esterification in the presence of N,N‐dicyclohexylcarbodiimide (DCC) and 4‐dimethylaminopyridine (DMAP). Their degrees of mesogenic unit substitution (DS_‐meso) were between 0.27 and 0.41. It was found that they can form cholesteric lyotropic phases in dichloroacetic acid and their critical concentration was about 25 wt %. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2693–2697, 2004     

热致型胆甾酯液晶的合成与表征

合成了十一烯酸胆甾酯及对－十一烯酰氧基－苯甲酸胆甾酯，并且用POM，DSC研究了它们的液晶性质。     

Synthesis and properties of side chain cholesteric liquid‐crystalline polyacrylates containing two mesogenic groups

The synthesis of side chain cholesteric liquid‐crystalline polymers containing both 4‐cholesteryl‐4'‐acryloyloxybenzoate (M_I) and 4‐methoxyphenyl‐4'‐acryloyloxybenzoate (M_II) mesogenic side groups is described. The chemical structures of the obtained monomers and polymers are confirmed by Fourier transform infrared (FTIR) spectroscopy. The phase behavior and optical properties of the synthesized monomers and polymers were investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and thermogravimetric analyses (TGA). The homopolymer IP reveals a cholesteric phase and VIIP displays a nematic phase. The copolymers IIP–VIP exhibit, respectively, cholesteric oily‐streak texture and focal‐conic texture. The fixation of the helical pitch and oily‐streak texture of the cholesteric phase is achieved by quenching, and polymer films with different reflection colors are obtained. The experimental results demonstrate that the glass transition temperature (T_g) and the melting temperature (T_m) of the copolymers IIP–VIP decrease, whereas the isotropization temperature (T_i) and the mesomorphic temperature range (ΔT) increase with increasing content of mesogenic M_II units. TGA results indicate that the temperatures at which 5% mass loss occurred (T_5wt%) of all copolymers are >245°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1936–1941, 2003     

New thermochromic liquid–crystalline polymer: Synthesis and phase behavior

A series of new thermochromic side‐chain liquid–crystalline polymers were prepared. The chemical structures of the resulting monomers and polymers were characterized by element analyses, FTIR, ¹H‐NMR, and ¹³C‐NMR. Their mesogenic properties were investigated by differential scanning calorimetry, thermogravimetric analyses, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of dye groups on phase behavior of the polymers was discussed. The polymers P₁–P₃ showed smectic phase, and P₄–P₇ revealed cholesteric phase. The polymers containing less than 30 mol % of the dye groups showed good solubility, reversible phase transition, wider mesophase temperature ranges, and higher thermal stability. Experimental results demonstrated that the clearing temperature and mesophase temperature ranges decreased with increasing the concentration of the dye groups. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 329–335, 2005     

Preparation and properties of optical notch filters of cholesteric liquid crystals

We investigated the influence of preparative conditions of cholesteric-liquid-crystal (CLC) solid films on their cholesteric structures. They are made of poly[γ-butyl- (or )-glutamate] (PBuL(D)G and triethylene glycol dimethacrylate (TGDM), and have the ability to reflect the light in a specified wavelength region. When these films were combined with conventional colour filters, the colour reproduction region was enlarged by about 25% in the area of the CIE chromaticity diagram.     

Mesomorphic transitions in a mixture of a flexible and a semi-rigid polymer

Phase studies on a mixture of two polymers are presented, one of which is mesomorphic. We have systematically examined the influence of the molecular weight of the flexible polymer (including the oligomers) and of the semi-flexible polymer. In addition to the effect of the molecular weight, specific interactions are important for compatibility and formation of a homogeneous mesomorphic phase. The nature of this phase is demonstrated to be cholesteric and the pitch is determined.