Synthesis and phase behavior of chiral side‐chain liquid‐crystalline polysiloxanes containing two mesogenic groups

The synthesis of chiral side‐chain liquid‐crystalline polysiloxanes containing both cholesteryl undecylenate (M_I) and 4‐allyloxy‐benzoyl‐4‐(S‐2‐ethylhexanoyl) p‐benzenediol bisate (M_II) mesogenic side groups was examined. The chemical structures of the obtained monomers and polymers were confirmed with Fourier transform infrared spectroscopy or ¹H‐NMR techniques. The mesomorphic properties and phase behavior of the synthesized monomers and polymers were investigated with polarizing optical microscopy, differential scanning calorimetry, and thermogravimetric analysis (TGA). Copolymers IIP–IVP revealed a smectic‐A phase, and VP and VIP revealed a smectic‐A phase and a cholesteric phase. The experimental results demonstrated that the glass‐transition temperature, the clearing‐point temperature, and the mesomorphic temperature range of IIP–VIP increased with an increase in the concentration of mesogenic M_I units. TGA showed that the temperatures at which 5% mass losses occurred were greater than 300°C for all the polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2670–2676, 2002     

2001—2002年国外塑料工业进展

收集了2001年7月到2002年6月有关国外塑料工业的相关期刊资料，介绍了2001年到2002年国外塑料工业的发展情况，提供了世界各地域塑料原材料的产量及构成比，日本，美国，加拿大，德国，法国，比利时，墨西哥，芬兰，西班牙等国家的树脂产量，消费量及增长率，以及日本，西欧，北美等地区的不同品种塑料原料消费量和增长率统计，按通用热塑性树脂（聚乙烯，聚丙烯，聚苯乙烯，聚氯乙烯，ABS树脂），工程塑料（尼龙，聚碳酸酯，聚甲醛，热塑性聚酯，聚苯醚），通用热固性树脂（酚醛，聚氨酯，不饱和树脂，环氧树脂），特种工程塑料（聚苯硫醚，液晶聚合物，聚醚醚酮）不同品种的顺序，对树脂的产量，消费量及合成工艺，产品应用开发，树脂品种的延伸及应用的进一步扩展等有关技术作了详细的介绍。     

Synthesis and mesomorphic properties of side‐chain cholesteric liquid‐crystalline polymers containing menthyl groups

A series of new cholesteric liquid‐crystalline polysiloxanes ( P₁ – P₅ ) derived from menthyl groups were synthesized. The chemical structures of the monomers and polymers were characterized with Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, and elemental analyses. The mesomorphic properties and thermal behavior were investigated with differential scanning calorimetry, polarizing optical microscopy, thermogravimetric analysis, and X‐ray diffraction measurements. The influence of the polymer structure on the thermal behavior was discussed. The monomer diosgeninyl 4‐allyloxybenzoate exhibited a typical cholesteric oily‐streak texture and a focal‐conic texture. Polymers P₁ – P₅ showed thermotropic liquid‐crystalline properties. P₁ displayed a smectic fan‐shaped texture, P₂ – P₅ showed a cholesteric Grandjean texture, and P₆ and P₇ did not show mesomorphic properties. The experimental results demonstrated that the glass‐transition temperature and the clearing temperature decreased, and the mesomorphic properties weakened with an increasing concentration of menthyl units. Moreover, P₁ – P₅ exhibited wide mesophase temperature ranges and high thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5559–5565, 2006     

Synthesis, characterization and biodegradation of biodegradable-cum-photoactive liquid-crystalline copolyesters derived from ferulic acid

Novel biodegradable-cum-photoactive liquid-crystalline copolyester was prepared by melt polycondensation of ferulic acid (FA), 4-hydroxybenzoic acid (HBA) and d,l-lactic acid (LA) in the presence of acetic anhydride and a transesterification catalyst. The chemical structures and properties of the synthesized copolyesters were characterized by means of viscosity measurements, Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (¹H NMR), differential scanning calorimetry (DSC), thermogravimetry (TGA), polarizing light microscopy (PLM) and ultraviolet spectroscopy (UV). It was found that modestly increasing LA content and adjusting feed ratios could enhance the solubility and biodegradability of the copolyesters, still retaining the liquid crystallinity. The obtained copolyester could degrade in phosphate buffer solution (pH 7.2) with enzyme proteinase K, and could crosslink by UV-irradiation at ambient temperature.     

当前工程塑料改性及加工的主要课题（III）

综述了用途广泛的几种工程塑料的改性和加工技术的进步及人们关注的重点。     

Manipulating ordered structure of ionic liquid crystalline polymers through tuning the alkyl spacer length

The fabrication of ordered structure is very important for the applications of ionic liquid crystalline polymers (ILCPs) or polymerized (ionic liquid crystal) (PILC). In this paper, we reported a facile approach to manipulate the ordered structure of ILCPs through adjusting the length of alkyl spacer. We designed and synthesized a series of ILCPs contained imidazolium, poly(2,5-bis{[m-(4-butoxy-4′-imidazolium phenyl) m-alkyl] oxy carbonyl} styrene bis (fluoroborate) salts) (denoted as P_4-m−BF₄, m represents the number of carbon in the alkyl spacers and m = 2, 4, 6, 10) via radical polymerization. Combined differential scanning calorimetry (DSC), polarized light microscopy (PLM), X-ray scattering, and two-dimensional wide-angle X-ray diffraction (2D WAXD), we found that the ordered structure of this ILCPs can transfer from smectic A phase (SmA) to hexagonal columnar (Φ_H) phase with the increase of spacer. Furthermore, these results were confirmed by reconstructed relative electron density map using fast fourier transform algorithm (FFT). The result revealed that the increase of alkyl spacer would affect the interaction between ions and side chain, and induce the packing of the side chains. It was evident that the alkyl spacer played an important role in the constructing of ordered structure and offered a new method to fabricate different ordered structure of ILCPs.     

Surface pretreatment of glass fiber-reinforced liquid crystalline polymer composites by excimer laser for adhesive bonding

This paper reports the results of using a new laser surface pretreatment technique to improve the strength of adhesive joints. A high power KrF excimer laser at 248 nm output was used to surface-treat a glass fiber-reinforced liquid crystalline polymer (LCP) composite. With optimum process parameters, the polymer matrix at the surface was etched away efficiently and the bare fibers anchored on the matrix were left dangling and undamaged. The surface morphology produced by this new technique resulted in high quality adhesive joints. Both lap-joint and butt-joint configurations were investigated. A 350% improvement in the butt-joint strength was achieved by this new pretreatment technique as compared with that of the untreated one.     

Synthesis and characterization of side-chain liquid crystalline polyoxetanes containing 4-(alkanyloxy)phenyl 4-pentylbenzoate side groups

The synthesis and characterization of side-chain liquid-crystalline polyoxetanes containing 4-(alkanyloxy)phenyl 4-pentylbenzoate side groups is presented. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction measurements were used to characterize the mesomorphic properties of the polyoxetanes. Those polymers with three to five methylene units in the spacers exhibit the enantiotropic smectic A and a nematic phaser, whereas the polymers with longer spacers (n = 6 or 12) display polymorphism of smectic phases. The polyoxetane backbones are amorphous in nature. No side chain crystallization occurred for any of the polyoxetanes synthesized in this study.     

基于线性互补问题的多体系统接触/碰撞动力学研究

多体系统往往包含大量的接触/碰撞行为,这些非光滑事件的存在造成了动力学方程的不连续或分段连续,给数值求解带来了很大的困难。为综合考虑平顺接触与碰撞,采用基于线性互补问题的非光滑动力学方法,首先在当前时刻为起点的短时间内对对缝隙函数进行均匀化,然后与法向接触力建立标准线性互补方程,最后将线性互补方程改造为一组非线性代数方程,通过非线性迭代可直接求解接触力。算例结果表明,采用该方法不需在接触状态发生改变时切换模型,且严格满足互补关系,保证了接触力的非负性。研究成果可成为求解多柔体系统接触/碰撞问题的新途径。     

高速网络PPP协议的实现及其安全机制的研究

研究了PPP协议在高速SDH／SONET光纤网络上的实现技术,并将其应用到高速路由器的工程实践中,实现的PPP协议软件向下和底层硬件驱动程序接口处理收到的PPP报文;向上和网络层协议IP,IPX接口将IP／IPX报文送交IP／IPX协议处理,形成发送网络层报文的控制机制。还研究了PPP协议的安全问题,包括协议的加密和认证机制,确保报文转发过程中的高速和安全性。