Synthesis of a series of chiral copolymers with azo groups and investigations of reversible liquid crystalline alignment induced by the LB films of these materials

A series of liquid crystalline copolymers, poly{2-hydroxyethyl methacrylate}-co-{6-[4-(S-2-methyl-1-butyloxycarbonylphenylazo)phenoxy]hexyl methacrylate} with an azobenzene moiety as photoreactive mesogenic unit, was prepared and investigated by using DSC, polarized optical microscopy and X-ray diffraction. The results show that these polymers exhibit smectic phases. Z-type Langmuir-Blodgett films of these copolymers were successfully deposited onto calcium fluoride and quartz. Reversible homeotropic and planar liquid crystal alignments were induced by using the photochromism of the LB films of one of the copolymers containing 20.6 mol % of the azo unit.

Ionic conductivity of polymer gel electrolytes based on poly(polyethylene glycol dimethacrylate)

Gel electrolytes have been prepared by thermal polymerization of poly(polyethylene glycol dimethacrylate) (P(PEGD)) in the presence of propylene carbonate (PC) and alkali metal salts, such as LiClO4, LICF(3)SO(3) and LiBF4. The conductivity was studied by means of impedance spectroscopy, and it is found that the temperature dependence of conductivities follow a Arrhenius relationship when the molar percentage of PC is higher than 75% or LiClO4 concentration is lower than 0.9 mol/l. However, when LiCF3SO3 or LiBF4 is used instead of LiClO4 as the salt, the situation is different. For LICF(3)SO(3), the Arrhenius relationship almost holds true for all the salt concentrations studied; while for LiBF4, the Arrhenius equation hardly fits for any salt concentration. The dependence of activation energy on salt concentration is also examined, both for LiClO4 and LiCF3SO3, the values of E(a) tend to reach a minimum value with increasing salt concentration. Copyright (C) 1996 Elsevier Science Ltd.

MOLECULAR-STATE OF GRAFT-COPOLYMERS IN THE INTERFACIAL AREA OF POLYOLEFIN AND POLAR POLYMER

In order to characterize the interface in polymer blends, a new method is suggested, in which the interface is exposed by selectively dissolving in solvent. By means of X-ray photoelectron spectrometry, we studied the molecular state in the interfacial ar

INFLUENCE OF ESTER GROUP-SIZE IN PMAS ON BETA-PHASE CRYSTALLIZATION OF PVF2 IN HIGHLY ORIENTED FILMS OF PVF2/PMAS BLENDS

Influence of ester group size in polymethacrylates (PMAs) , including PMMA, PEMA and PBMA, on beta phase crystallization of poly(vinylidene fluoride) (PVF2) in highly oriented films of PVF2/PMAs=80/20 blends has been investigated by FTIR and TEM. The melt-drawn films of pure PVF2 consist of highly oriented lamellae, in which the alpha phase is predominant. Adding a given amount of PMAs (20 wt%) into PVF2 results in formation of fibrillar crystals and increase of relative amount of the beta phase. The influence extent is in order of PMMA > PEMA > PBMA, regarding the ester group size in the PMAs.

MISCIBILITY OF POLY(N-VINYL-2-PYRROLIDONE) WITH POLY(ETHER SULFONE) AND 2 PHENOLPHTHALEIN-BASED POLYMERS

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) with poly(ether sulphone) and two phenolphthalein-based polymers, viz. phenolphthalein poly(ether ether sulphone) and phenolphthalein poly(ether ether ketone) were prepared by casting from a common solvent and studied by differential scanning calorimetry. It was found that all the PVP blends are miscible and show a single, composition-dependent glass transition temperature (T(g)). The T(g)-composition dependence has been analysed by the use of the Gordon-Taylor equation. The values of the k parameter in the Gordon-Taylor equation obtained are all not high for the three pairs, in accordance with the fact that there is no strongly specific interaction between PVP and any of the other polymers.

MISCIBILITY OF POLY(N-VINYL-2-PYRROLIDONE) WITH A COPOLYAMIDE

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) with a copolyamide (CoPA) randomly composed of 1:1:1 (wt) nylon 6, nylon 66 and nylon 610 structural units were prepared by casting from a common solvent. They were found to be miscible and show a single, composition-dependent glass transition temperature (T(g)). The addition of PVP to CoPA significantly lowers the crystallinity owing to an increasing T(g) of the system. The observed miscibility is proposed to be the result of specific interactions between the proton acceptor groups of PVP and the amide groups of CoPA.

CRYSTALLIZATION OF POLY(ARYL-ETHER-ETHER-KETONE)S BLENDS

The crystallization and melting behaviour of poly(aryl-ether-ether-ketone) (PEEK) in blends with another polymer of the same family containing a bulky pendant phenolphthalein group (PEK-C) have been investigated by thermal methods. The small interaction energy density of the polymer pair (B = -8.99 J/cm3), evaluated from equilibrium melting point depression, is consistent with the T(g) data that indicate partial miscibility in the melt. Two conjugated phases are in equilibrium at 430-degrees-C: one is crystallizable and contains about 35 wt% of PEK-C; the other, containing only 15 wt% of PEEK, does not form crystals upon cooling and it interferes with the development of spherulites in the sample. The analysis of kinetic data according to nucleation theories shows that crystallization of PEEK in the explored temperature range takes place in Regime III and that a transition to Regime II might be a consequence of an increase in the amount of non-crystallizable molecules in the PEEK-rich phase. A composition independent value of the end surface free energy of PEEK lamellae has been derived from kinetic data (sigma-e = 40 +/- 4 erg/cm2) in excellent agreement with previous thermodynamic estimates. A new value for the equilibrium melting temperature of PEEK (T(m)-degrees = 639 K) has been obtained; it is about 30-degrees-C lower than the commonly accepted value and it explains better the "memory effect" in the crystallization from the melt of this high performance polymer.

EFFECT OF MOLECULAR-WEIGHT OF PMMA ON BETA PHASE CRYSTALLIZATION IN HIGHLY ORIENTED PVF2 FILMS

Polyvinylidene fluoride (PVF_2) exhibits at least four crystalline phases (α, β, γ, and δ). Among them, β phase is the most important one because it is directly related to the piezoand pyro-electric activities of PVF_2. In recent years, more attention has been paid to the β

EFFECT OF CRYSTAL-FIELD AND BONDING PROPERTIES ON SPECTRAL STRUCTURE OF EU-2+

Five Eu~(2+)-doped simple fluorides and six Eu~(2+)-doped complex fluorides are synthesized by solid reactions. The strength of the crystal-field at the sites of Eu~(2+) ion, and the degroe of covalenco of Eu—F bond in these hosts are discussed. The f-f transition emission of Eu~(2+) ion is observed in the hosts which has lower coordination number and strong crystal-field. The f-f transition emission of Eu~(2+) ion is observed for the first time in the simple fluoride AlF_3.

STUDY ON ION-IMPLANTATION OF EUROPIUM INTO CAF2 SINGLE-CRYSTAL

CaF_2 single crystal is very useful as optical host materials. It has been systematically studied and widely used in thermoluminescence that rare earth ions were doped into CaF_2 single crystal with chemical methods. However, the ion implan-

Studies on the hemolytic activity of tentacle extracts of jellyfish Rhopilema esculentum Kishinouye: Application of orthogonal test

The present work is first reporting the hemolytic activity of venom from jellyfish Rhopilema esculentum Kishinouye extracted by different phosphate buffer solutions and incubated at different temperature according to the orthogonal test L6(1) x 3(6). Of the seven controllable independent variables, incubated temperature and phenylmethylsulfonyl fluoride (PMSF) had strongest effect on the hemolytic activity. (c) 2006 Elsevier B.V. All rights reserved.

基于PVDF的亚μN微力传感器的研究

本文设计了一种新颖的微力感知传感器及其标定方法,以获得亚μN(micro Newton)的可靠的、高精度力反馈信息。可靠的、高精度的微力感知和控制在提高微装配的效率上具有重要的作用。目前微装配中还没有可靠的亚μN分辨率的传感器。本文以PVDF(polyvinylidene fluoride)为基本材料,建立出PVDF传感器所受的微力与输出电压之间的关系模型,开发出相应的信号处理电路,并对PVDF传感器的上述模型进行了标定。实验结果表明本文开发的PVDF传感器具有亚μN的分辨率,同时验证了本文建立的PVDF传感器模型的正确性,并证明了信号处理电路以及标定方法是有效的。本文设计的微力传感器为微装配和微操作中微接触力的反馈控制提供了可靠的解决方法,并将促进微装配和微操作的自动化加工技术水平,实现微型装备的可靠、高产量的批量制造。

氟代谢平衡及其在地方性氟中毒防治中的应用研究

本文通过氟代谢平衡法，研究了大鼠在不同氟摄入量条件下以及食物高钙、高蛋白质、酸性饮水、碱性饮水，大鼠氟的摄入、排泄和蓄积的特征；并对氟代谢的指标之一，尿氟含量在地方性氟中毒防治中的应用进行了分析；同时，以大鼠氟代谢作为低氟玉米样品氟富集的载体，采用生物富集方法，探索性测定了测定超低氟含量玉米样品。通过实验观察，得到以下几点主要认识： 1. 氟的蓄积量从高到低的次序是：常规食料组＞碱性饮水组＞酸性饮水组＞富蛋白饲料组＞富钙饲料组。高钙和高蛋白饮食减少了大鼠的饮水量和摄食量，使高氟含量的饮水和食物进入机体的量减少，从而减少了摄氟量。高钙食物和高蛋白质食物，促使尿氟浓度显著增高，骨氟浓度减低，降低了大鼠的氟蓄积。高钙食物使粪排氟量比例增加，高蛋白食物使尿排氟量比例增加。 2. 大鼠生长过程中，一般在3个月时代谢旺盛，摄氟量、蓄积量和排氟量大幅增加。 3. 大鼠摄入过量氟导致骨形态学改变。随着实验时间加长，大鼠摄氟量增加，电镜下骨细胞出现凋亡和坏死数量增多，有的成骨细胞出现细胞器变性，骨基质发育不良；骺板仅见软骨细胞减少，未见细胞器变性，软骨基质未见异常。 4. 人群群体尿氟，对于氟中毒评价病情、环境氟暴露有重要意义，在地方性氟中毒防治工作中是一个可用于实际工作的指标。判定病区与非病区表准的人群尿氟几何均数为：成人1.6mg/L，儿童1.4mg/L。 5. 利用大鼠氟代谢平衡法测得新鲜玉米氟含量为：0.35mg/kg，其范围可能在0.01~0.69mg/kg之间，此方面还需进一步研究。