侧链液晶聚乙炔的合成及性能表征

取向液晶侧链引入聚乙炔主链促使主链共轭性提高,导致获得电活性和取向性的永久结合。最近,已有不少研究组将聚炔共轭聚合物作为刚性主链应用于制备侧链液晶聚合物。文中主要阐述带有液晶侧链聚乙炔的合成、液晶性及光学性能,并根据侧链液晶基元结构对其进行分类。     

共轭高分子三阶非线性光学材料

概述了ｎ－共轭高分子材料的三阶非线性光学性质，着重讨论了化学结构对其光学非线性的影响，说明了ｎ－共轭聚合物的三阶非线性极化率主要取决于共轭主链的结构，侧链取代基的变化对其非线性影响不大，文中展望了共轭高分子材料在集成光学中的应用前景。     

用红外光谱法研究橡胶/炭黑的界面相互作用

用红外光谱法(FI-IR)研究了橡胶微观结构、炭黑表面基团对橡胶/炭黑的界面相互作用的影响。研究表明,炭黑加入后各分子基团的振动均发生红移。炭黑与富电子的分子链相互作用大,即天然橡胶(NR)>丁基橡胶(BR)>丁苯橡胶(SBR)>丁腈橡胶(NBR);对侧基的影响小于对主链的影响。极性基团丙烯腈含量(ACN)增加,除ν(C≡N)外碳链上的其它基团均发生蓝移,且支链上双键基团所受影响最大。炭黑加入后,减弱了ACN含量增加对链段间作用力的影响,随ACN含量增加各基团蓝移较纯胶的小。门尼黏度仅影响δCH2的振动峰位。     

聚氨酯型高分子二苯甲酮光引发剂的制备及性能

合成了含有2个活性羟基的二苯甲酮单体4-(2,3-二羟基)丙氧基二苯甲酮(HPBP),然后将HPBP、二异氰酸酯和N-甲基二乙醇胺进行逐步聚合反应,制备了侧链含二苯甲酮,主链含共引发剂胺的聚氨酯型高分子二苯甲酮光引发剂。红外光谱和核磁共振氢谱证实了高分子光引发剂的结构;紫外-可见吸收光谱研究表明高分子光引发剂的结构对二苯甲酮单元的最大紫外吸收几乎没有影响;用光致差示扫描量热仪研究了高分子光引发剂和HPBP引发聚氨酯丙烯酸酯(PUA)的光聚合反应,结果表明,高分子光引发剂的主链结构对其引发性能影响显著。     

聚乙烯醇侧链液晶高分子的合成与表征

合成了聚乙烯醇侧链液晶高分子并对其进行表征.利用聚乙烯醇中羟基的给质子能力和苯乙烯吡啶上氮原子的授质子能力形成的氢键,通过分子自组装合成聚乙烯醇侧链液晶高分子.这是一种热致性向列型液晶高分子.由于聚乙烯醇主链良好的柔顺性,该侧链液晶高分子具有较低的相转变温度和较宽的液晶温度范围.同时,通过氢键连接液晶基元和聚合物主链,相对减弱了液晶基元与聚合物之间的相互作用力,使它们之间保留了一定的自由性,提高了侧链液晶高分子的柔顺性,扩大了其使用范围。     

新型高分子膜在阳光下会运动

<正>据媒体报道,日本科研人员研制出了一种高分子膜,在光线照射下,这种材料的分子相对位置会发生变化。这一成果有望应用于仿生医学和太阳能电池开发。有关研究成果发表在新近一期的美国《科学》杂志上。研究人员选择能在光照下改变自身结构的偶氮苯分子,让它们与一种分子主链周围垂直密布许多侧链的刷子状高分子"聚合物刷"想     

侧链末端为磺酸基团的磺化聚砜阳离子交换膜性能研究

参照前期的研究方法,采用两步一锅法,首先在聚砜(PS)主链上引入活性基团—NCO,紧接着与对羟基苯磺酸钠(HBS)反应制备一种侧链末端为磺酸基团的磺化聚砜(PS-BS),采用流延成膜法制备相应的聚砜阳离子交换膜(PSCEM)。研究温度与PSCEMs吸水率、尺寸稳定性和质子传导率性能之间的关系,由于亲水磺酸基团远离在聚砜主链,能够形成亲水微区远离疏水主链的微相分离结构,使PSCEM在高的吸水率条件下保持较好的尺寸稳定性。在反应时间为15h条件下,制得的PSCEM在25℃和85℃的吸水率为45.1%和52.1%,吸水溶胀率仅为25.1%和55.6%,质子传导率分别为0.077S/cm和0.147S/cm,具有较好的性能。     

基于Bergman环化反应合成刷状高分子

以含有烯二炔结构的枝状化合物单体在真空、282℃条件下,通过Bergman环化反应,热聚合为具有刚性的共轭主干、带有枝状化合物侧链的刷状高分子聚合物。核磁共振光谱、广角光散射、凝胶色谱、红外光谱、紫外-可见光谱等表征结果,证明所合成的两种聚合产物确实是具有共轭结构的刷状高分子。     

高分子链运动对氧气扩散行为的影响

以聚乙烯(PE)为研究对象,基于分子动力学模拟从温度、结构和扩散激活能等角度来研究高分子链长、主链段活跃性、端基运动和分子链取向对氧气分子(O_2)在聚乙烯中扩散行为的影响。基于COMPASS力场构建具有三维周期性边界的扩散模型(O_2/PE),对该模型优化得到的稳定构型进行分子动力学模拟。结果表明,高分子链运动对气体的扩散行为有较大的影响。对高分子链端基均方位移(MSD)以及末端距与扩散系数的关联分析表明,主链活跃性提高,有利于形成更多的"扩散通道",使分子扩散速率提高。短链活跃性高于长链,柔顺性低于长链,分子链越短自身碰撞频率越低,因此分子跃迁的自由体积增大,扩散速率升高。此外,施加拉伸载荷会使高分子链沿载荷方向取向,降低晶胞对称性,使分子扩散速率显著提升。     

用粘度法估算高分予链的构型特征

高分子稀溶液的研究工作,主要是在溶液中表征高分子的一些结构参数,例如分子量,分子的尺寸和形态,高分子与溶剂的相互作用等;以及发展高分子的溶液理论。从实验测定方面来说,有热力学的方法(沸点升高、冰点下降、渗透压、光散射等。)和动力学的方法(粘度、超速离心,光子相关光谱等。)本文介绍如何用最简单的粘度法来估算高分子链的构型特征。     

Influence of the Association of Rigid and Flexible Macromolecules on Their Compatibility

Consideration is given to a melt of rigid rodlike macromolecules whose side mainchain links are capable of associating with active end groups of flexible chains (it is assumed that each flexible chain has only one active end group), thus forming associated complexes. It is shown that with decrease in the temperature the association facilitates substantial improvement in the compatibility of rigid and flexible molecules in the melt.     

Spherical particle preparation of Na+-ion conductive Na4Zr2Si3O12 by mist pyrolysis

Spherical polycrystalline particles of Na₄Zr₂Si₃O₁₂ (NZS) have been prepared by a mist pyrolysis technique with alkoxide ethanol solution. Firing the precursor particles, obtained by pyrolysing at 550 °C, yielded the NZS with the highest S/N ratio and the least second phase at 1000 °C. Each spherical particle with an average size of 0.5 m was composed of primary particles of 0.1 m diameter after firing. Comparing the particle formation process with the sol-gel, alkoxide pyrolysis and the aqueous solution processes, it would appear that the primary particle size of the mist-pyrolysed NZS depends on the size and residual alkyl group content of the precursor polymers.     

壳聚糖醋酸水溶液粘度行为的研究EI

在研究壳聚糖醋酸水溶液粘度行为的实验基础上,研究了前人提出的描述聚电解质溶液粘度与浓度经验关系的适用性,并且提出了一套较为合理的常数确定方法。同时提出了一个新的经验式,该经验式不仅浓度适用范围较宽,而且能适用于其他类型的聚电解质溶液体系。文中还讨论了柔性链聚电解质溶液粘度行为与刚性链聚电解质溶液粘度行为的差别以及产生这种差别的原因。     

Acetonitrile covalent adduct chemical ionization mass spectrometry for double bond localization in non-methylene-interrupted polyene fatty acid methyl esters

Covalent adduct chemical ionization (CACI) using a product of acetonitrile self-reaction, (1-methyleneimino)-1-ethenylium (MIE; CH2=C=N+=CH2), has been investigated as a method for localizing double bonds in a series of 16 non-methylene-interrupted fatty acid methyl esters (NMI-FAME) of polyenes with three and more double bonds. As with polyunsaturated homoallylic (methylene-interrupted) FAME and conjugated dienes, MIE (m/z 54) reacts across double bonds to yield molecular ions 54 mass units above the parent analyte. [M + 54]+ ions of several 20- and 22-carbon FAME that include one double bond in the C2-C3 position separated by two to five methylene units from a three, four, or five C homoallylic system dissociated according to rules for the homoallylic system, with an additional fragment corresponding to cleavage between the lone double bond and the carboxyl group and defining the position of the lone double bond. Triene FAME with both methylene and ethylene interruption yielded characteristic fragments distinguishable from homoallylic trienes. Fragmentation of fully conjugated trienes in the MS-1 spectra yields ratios of [M + 54]+/[M + 54 - 32]+ (loss of methanol) near unity, which distinguishes them from homoallylic FAME having a ratio of 8 or more; collisionally activated dissociation of [M + 54]+ yields a series of ions, including some rearrangement products, indicative of double bond position. Unlike conjugated dienes, fully conjugated triene diagnostic ion signal ratios did not follow any pattern based on double bond geometry. Partially conjugated trienes behave similarly to monoenes and conjugated dienes, yielding [M + 54]+/[M + 54 - 32]+ of 2-3 and, permitting them to be assigned as partially conjugated FAME using the MS-1 spectrum. They yield unique MS/MS spectra with weaker but assignable fragment ions, along with a diagnostic fragment that locates the lone double bond and permits 6,10,12-octatrienoate to be distinguished from 6,8,12-octatrienoate. The presence of a triple bond did not affect fragment formation in a methylene-interrupted yne-ene but did change fragments in a conjugated yne-ene. These data extend the principle of double bond localization by acetonitrile CACI-MS/MS to double bond structure in complex FAME found in nature.     

Coating of CaTiO3 on titanium substrates by hydrothermal reactions using calcium-ethylene diamine tetra acetic acid chelate

Titanium plates were treated in [Ti(O₂)EDTA]^2-– -Ca(EDTA)^2- mixed solutions and/or Ca(EDTA)^2- solutions (where EDTA is ethylene diamine tetra acetic acid) at pH 9–13 and 150–250 °C for 0.5–12 h. The film, about 50 m thick, and consisting of mixtures of CaTiO₃ and TiO₂ was formed in 0.01 M [Ti(O₂)EDTA]^2- – 0.01 M Ca(EDTA)^2- mixed solution at pH 13 and 250 °C for 6 h. The film consisted of large icosahedral and hexagonal particles, of about 10 m diameter, and small aggregated particles, of about 1 m diameter. On the other hand, the film, about 20 m thick, consisted of hexagonal plate-like CaTiO₃ particles, of about 1 m diameter, was formed in 0.01 M Ca(EDTA)^2- solution at pH 13 and 250 °C for 6 h. The thickness of both films increased with time, where the film formation rate in 0.01 M [Ti(O₂)EDTA]^2- – 0.01 M Ca(EDTA)^2- mixed solution was much faster. The CaTiO₃ film formed on the surface of titanium promoted the precipitation of hydroxyapatite on the substrate by the hydrothermal reactions in Ca(EDTA)^2-–PO ₄ ^3- mixed solutions.     

Rheological Model of Flow of a Material with a Variable Structure under Superplastic Deformation

Versions of rheological models describing the phenomenological behavior of materials in the superplasticity state with allowance for the elastic component and without allowance for it have been presented. Consideration has been given to the basic indications of manifestation of superplastic properties from the viewpoint of the influence of the dimensions of the structural components on them. Analytical dependences of the governing relations of the mechanics of a deformable rigid body, which allow for the influence of the applied stresses, the structure, and the temperature on the rate of superplastic deformation (SPD) and enable one to calculate the shear viscosity and the rheological dependences of SPD for deformable aluminum alloys AMg4 and AMg6 with a prepared ultrafinegrained structure, have been given.     

Synthesis and characterization of novel D–A porphyrin-containing copolymers for polymer solar cells

A novel asymmetrical D–A zinc porphyrin derivative with dimehtyl triphenylamine (donor unit) and methyl benzoate (acceptor unit) as para-arms was first synthesized. Then, two new copolymers (P1 and P2) containing D–A zinc porphyrin derivatives were synthesized by the Stille coupling method and applied in PSCs. Their structures, photophysical and electrochemical properties were characterized by ¹H NMR, ¹³C NMR, gel permeation chromatography, thermogravimetric analysis, UV–vis absorption spectroscopy, photoluminescence spectroscopy, and cyclic voltammetry. The two copolymers exhibited good thermal stability and film-forming ability. The results showed that P1 containing D–A zinc porphyrin exhibits a strong absorption in the range of 400–500 nm. By the introduction of thiophene derivative with 4,7-di(4-hexylthiophen-2-yl)benzothiadiazole (T-DTBT) conjugated side-chain unit, P2 showed broader absorption in the region of 300–650 nm than P1. The photoluminescence spectra made clear that charge transfer between the whole main chain and side chain can be effective. Cyclic voltammograms revealed that the LUMO energy levels of P2 was reduced in comparison with P1 due to the introduction of electron-deficient T-DTBT conjugated side-chain unit, indicating that electron-injection and transporting properties have been improved. Polymer solar cells were fabricated based on the blend of the copolymers and methanofullerene[6,6]-phenyl C₆₁-butyric acid methyl ester (PC₆₁BM). The PSC based on P2:PC₆₁BM (1:2, w/w) exhibited a power conversion efficiency of 1.26% under AM 1.5, 100 mW cm⁻².     

Structure-fracture measurements of particulate gels

Images on a micron scale and the stress-strain behaviour of gel structures during tension were simultaneously recorded in real time using a mini fracture cell under the confocal laser scanning microscope (CLSM). -lactoglobulin gels tailor-made to vary in density, connectivity, thickness of strands and size of aggregates and clusters were used as a food model system. Amylopectin and gelatin were used to generate different types of -lactoglobulin network microstructures and also as a second continuous phase.Both rheological and structural differences in fragility between -lactoglobulin gels were verified according to the density of their aggregated network structure. A dense gel has a more brittle behaviour where the clusters are rigid and the crack propagates smoothly compared to a gel with an open network structure, which has a discontinuous crack growth, via a winding pathway around clusters, and also break-up of the pores far from the crack tip. Differences in the stretchability of the aggregated -lactoglobulin structure, induced by addition of amylopectin solution, were proved and related to differences in stress-strain behaviour and crack propagation.Gelatin gels in the pores between the -lactoglobulin clusters do not affect the structure of the -lactoglobulin network but make the fracture fragile giving a smooth fracture surface, cause continuous crack growth and fracture propagation through -lactoglobulin clusters. This is a consequence of that the mixed gel follows the behaviour of the gelatin gel when the gelatin phase is stronger than the -lactoglobulin network.     

Synthesis and thermal behaviour of alkaline earth cyclo-octaphosphates

Hydrated alkaline earth cyclo-octaphosphates were made by adding an aqueous solution of alkaline earth chlorides into an aqueous solution of sodium cyclo-octaphosphate. Thermal properties of the compounds were studied by TG-DTA analysis. The water of crystallization was removed below 200°C. The cyclo-octaphosphates decomposed to produce many phosphate species up to about 500°C, and they finally reorganized to metaphosphates. The overall thermal reaction of alkaline earth cyclo-octaphosphates can be written by the equation. M4(PO3)8 · nH2O 4M(PO3)2 + nH2O     

Structure-performance-fouling studies of polysulfone microfiltration hollow fibre membranes

Hollow fibre microfiltration membranes were prepared by solution spinning process using polymer dope containing different amounts of polysulfone (PS), polyvinylpyrollidone (PVP) and ${\bf \textit{N}}$ , ${\bf \textit{N}}$ -dimethylformamide (DMF). Spinning dope having PS: PVP: DMF (w/w) of 15: 5: 80, 15: 7: 78 and 17: 8: 75 were used for spinning to obtain hollow fibres having different dimensions (outer and inner diameters) and pore characteristics. Relatively high water permeability was observed for hollow fibre membrane spun from 15?wt.?% solution than 17?wt.?% PS solution having the same PVP/PS ratio of 0·47. Decrease of the PVP/PS ratio to 0·33 in the dope solution of 15?wt.?% PS solution produced hollow fibre membrane with lower flux. By changing the spinning parameters, fibre with different dimensions were obtained without a significant change in microstructural morphology. The flux decline due to fouling for the permeation of PEO/BSA solution was maximum for the hollow fibre membrane obtained from 15?wt.?% PS solution while a steady flux with slight fouling was observed for the hollow fibre membrane obtained from 17?wt.?% PS solution, when the PVP/PS ratio was 0·47.