磺化酞菁铜单分子复合膜及其光电导性研究

用吸附法制备了无脂链磺化酞菁铜LB膜,紫外光谱表明所制备的LB膜具有很高的有序性。以上述磺化酞菁铜LB膜为光生层,制备了机能分离型有机光电体。研究结果显示经结晶紫敏化后的该类光电导体具有良好的光导特性。这与磺化酞菁铜分子排列的高度有序有关。     

C_(60)/花生酸混合LB膜 Ⅰ.LB膜的X射线衍射和分子排列模型

制备了纯C60和C60／AA的混合LB膜。用X－射线衍射详细研究了它们的周期结构,表明C60分子在C60／AA混合LB膜中不是顶在花生酸疏水端头,而是包埋在花生酸分子之间。由此提出了一个新的分子排列模型。     

聚酰亚胺的各向异性

由于聚酰亚胺分子链的刚性，在成膜过程中，其分子链沿膜平面排列（取向），构成了各向异性，导致膜平面方向与垂直于膜平面方向的物性参数（如折射率、介电系数）不相同。文中总结了各种研究聚酰亚胺膜各向异性的方法，证明聚酰亚胺膜具有各向异性。     

利用STM制作有机LB膜超高密度存储器

利用有机材料制作高密度存储器是当前纳米电子学研究的一个热点.有机LB膜的有序分子排列和能精确控制厚度的膜层被认为是高密度存储器理想的基体.具有原子分辨率及纳米量级局域作用微区的扫描隧道显微镜(STM)的出现则提供了制作超高密度存储器一种有力的高技术手段.本文介绍利用STM在有机LB膜上制作超高密度存储器.以硬脂酸制备多层LB膜,其形貌由STM成像.施加于STM针尖上的脉冲偏压,在LB膜表面的局域区域产生足够的强电场,使该微区转换为低阻导电状态,以高、低阻态分别表示两种逻辑状态,就完成了一次"写入"操作.LB膜材料的高、低阻态由STM的伏安特性(I-V)和扫描隧道谱(dI/dV-V)加以表征.用幅值较小的脉冲实现"读出"操作.该材料LB膜上存储的信息能保持很长时间,显示了潜在的应用前景.     

Langmuir-Blodgett膜的低角X射线衍射分析

低角X射线衍射是研究LB膜结构的有力工具,它能确认LB膜中成膜分子的排列规则性,确定LB膜的等同周期,计算LB膜厚,确定LB膜类型,成膜分子在基片上的倾斜角度和两种分子在混合LB膜中的排列,研究成膜分子在LB膜上的聚合,LB膜在酸碱环境下的稳定性,衍射峰的奇偶起伏现象等。     

用STM第一次观察到聚乙烯晶片的折迭链结构

通常人们认为聚乙烯薄膜是绝缘体,聚乙烯晶片的表面形貌是分子链的折迭部分,多是无规排列的,不能用扫描隧道显微镜(STM)研究聚乙烯薄膜的表面形貌。我们研究了聚乙烯薄膜的电学特性和结构特性,极薄的聚乙烯晶片在强电场下,有nA级的传导电流,因此可以用STM分析聚乙烯晶片的表面形貌。我们用STM首次观察到了聚乙烯晶片表面折迭链的周期结构。     

聚酰亚胺膜的功能化及成膜过程中影响因素分析

膜分离技术以其高效节能的优势,己广泛应用于生产生活的各个领域,是解决目前能源危机和环境恶化问题的有效手段。理想的膜材料要同时具有较高的渗透性和较强的分离选择性,大量研究表明聚酰亚胺膜的综合性能突出,是制备气体分离膜的首选材料,但是由于其结构中含有极性较强的酰亚胺基团,分子链中含有苯环或芳杂环,不利于分离膜的制备和小分子物质的通过导致膜的渗透通量不高,因此需要对聚酰亚胺膜进行功能化改性来满足工业化应用的要求。介绍了聚酰亚胺膜功能化的主要手段,探讨聚酰亚胺膜成膜过程中的影响因素,展望未来聚酰亚胺膜的研究方向,为合成性能优异的聚酰亚胺膜提供理论基础。     

三明治型酞菁铽LB膜的制备研究

采用表面压-面积（π-A）等温曲线和紫外-可见吸收光谱研究了三明治型酞菁铽（TbPcPc＊）分子在langmuir膜及其langmuir-blodgett（LB）膜中分子的存在状态和光谱特性．实验结果发现TbPcPc＊分子在亚相表面可以形成稳定的langmuir膜，在langmuir中以edge-on方式面对面的排列，且具有较好的成膜性能，可以制成多层X型LB膜。TbPcPc＊分子在氯仿溶液和LB膜中形成了H-聚集体，形成LB膜后，由于双酞菁分子之间排列紧密，相互作用加强，使得薄膜中分子聚集体的吸收峰相对于溶液中聚集体的吸收峰发生了一定的红移。     

聚酰亚胺及其LB膜光电导性研究进展

对芳香性聚酰亚胺及其Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ膜的光电导性研究作了总结,讨论了分子链结构、取向、掺杂等因素对其光电导性的笔电荷转移络合物的光电导机理。结果表明,给电子基团的引入有利于分子链间电荷转移络合物的形成,从而提高其光敏性;大分子链的堆积和高度有序的排列、取向,有利于光生载流子的定向全和光电导性能的提高。     

LB膜的制备及表征研究进展

LB膜技术是基于分子水平制备精确有序、厚度可控的超薄膜的先进技术,广泛应用于组装纳米功能材料和分子器件。介绍了LB膜技术的研究发展历程,综述了LB膜的制备方法、制备过程和表征手段,对LB膜技术未来发展趋势进行了展望。     

Magnetic properties of ferrocenylmethylacrylate-N-dodecylacryl-amide copolymer Langmuir–Blodgett films

Langmuir–Blodgett (LB) films of the copolymer with ferrocenyl-methyl-acrylate (FcMA) and N-dodecyl-acrylamide (DDA) were fabricated. The magnetic moment of these LB films became about twenty times larger than that of the powder. In addition, the LB films had a magnetic anisotropy depending on the dipping direction. The FTIR results suggested that the polymer chains in the LB films were preferably aligned with the perpendicular of the dipping direction. These results were discussed by the intermolecular electron transfer.     

Optical and electrical properties of merocyanine dye LB films by various time of UV irradiation and heat treatment

The Langmuir-Blodgett (LB) technique provides many possibilities for the control of film thickness, dimensions, and molecular structures on the nanometer scale. Various kinds of dye molecules have been found to form the J-aggregation which has been used as sensitizers of silver halide photography for long time. In recent years, they attract attention as model systems for investigating the ultra-fast exciton dynamics, materials for ultra-fast nonlinear optical devices, fluorescence probes for mitochondrial membranes. We fabricated the merocyanine dye LB films with arachidic acid (AA). In order to observe the J-aggregation of the merocyanine dye LB films, CdCl2 and KHCO3 solutions were added in subphase. From the optical absorption spectra of the mixed dye LB films (6Me-Ds:AA = 1:2) at different layers, the optical absorption peak was about 520 nm. However, the optical absorption peak of the LB films was shifted to 600 nm, when CdCl2 and KHCO3 solutions were added. This is the consequence result to the J-aggregation of the merocyanine dye. We also investigated the optical absorption peak of the LB films according to various time at 60 degrees C and 275 nm UV. We measured the STM morphology of the merocyanine dye LB film (1 layer) before UV irradiation and heat treatment. The morphology size of the LB film on HOPG was 5 nm. The roughness and molecular size were about 66.163 pm and 0.176 nm, respectively. The J-aggregation of this type was also accompanied by large morphological changes. We analyze the morphology and electrical properties of the LB films by the scanning tunneling microscopy (STM).     

Proteolytically Degradable Photo‐Polymerized Hydrogels Made From PEG–Fibrinogen Adducts

We develop a biomaterial based on protein–polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate‐functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein–polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non‐cross‐linked and UV cross‐linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20 kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free‐radical polymerization cross‐linking reaction in the hydrogel precursor solution. As expected, the conjugated protein‐polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free‐radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross‐linking kinetics and stiffness of the cross‐linked hydrogel are highly influenced by the protein–polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein–polymer conjugates proves to be were different from those of the non‐conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG–protein adduct. A more complete understanding of the molecular complexities associated with this type of protein‐polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins.     

Mechanical properties of carbon nanotube reinforced polymer nanocomposites: A coarse-grained model

In this work, a coarse-grained (CG) model of carbon nanotube (CNT) reinforced polymer matrix composites is developed. A distinguishing feature of the CG model is the ability to capture interactions between polymer chains and nanotubes. The CG potentials for nanotubes and polymer chains are calibrated using the strain energy conservation between CG models and full atomistic systems. The applicability and efficiency of the CG model in predicting the elastic properties of CNT/polymer composites are evaluated through verification processes with molecular simulations. The simulation results reveal that the CG model is able to estimate the mechanical properties of the nanocomposites with high accuracy and low computational cost. The effect of the volume fraction of CNT reinforcements on the Young's modulus of the nanocomposites is investigated. The application of the method in the modeling of large unit cells with randomly distributed CNT reinforcements is examined. The established CG model will enable the simulation of reinforced polymer matrix composites across a wide range of length scales from nano to mesoscale.     

Microscopic and spectroscopic study of self-ordering in poly(3-hexylthiophene)/carbon nanotubes nanocomposites

Poly(3-hexylthiophene)-single-walled carbon nanotubes (SWNTs) composites were studied using UV-visible absorbance and Raman spectroscopy, scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). Monolayers of regioregular poly(3-hexyl thiophene) (rrP3HT) adsorbed on SWNTs have been imaged using scanning tunneling microscopy (STM) to obtain measurements of the chiral angles at which the thiophene polymer chains wrap around individual carbon nanotubes (41-48 degrees with respect to nanotube axis) and polymer interchain spacings (1.68 angstroms). The rrP3HT interchain distance is greater for rrP3HT monolayers adsorbed onto the curved surfaces of SWNTs than on the flat surfaces of highly ordered pyrolytic graphite samples (1.4 angstroms). UV-vis spectroscopic data provided strong evidence for increased interchain interactions in composites of rrP3HT and SWNTs compared to the pure polymer. The STM local-probe studies of the native polymer and the composites further confirmed that the rrP3HT interacts with carbon nanotubes to produce a highly ordered material at the molecular level.     

聚苯乙炔单分子膜成膜特性研究

研究了聚苯乙炔单分子膜的成膜特性及其结构，结果表明，聚苯乙炔能在较大的表面压范围内形成稳定的单分子膜，并具有不可重复压缩性，表面压力的各向异性和松弛特性，ＴＥＭ照片显示，聚苯乙炔分子链在单分子膜中是有序排列的，转移比和ＸＰＳ研究证明，单分子膜向铝片的沉积是成功的。     

Anisotropic behaviour of the glass transition temperature in thin films of Langmuir-Blodgett deposited side chain polymers

Langmuir-Blodgett (LB) films of side chain polyamic acids were formed, deposited onto optical waveguides and imidized via heating to the corresponding polyimides on the optical waveguides. The LB film formation of the side chain polyamic acids, the imidization reaction and the glass transition behaviour of the polyimide thin films were investigated. Polarisation dependent waveguide mode spectroscopy was applied therefore. It was found that the glass transition temperature (Tg) of bulk and LB thin film samples of these polymers are identical and only depend on the spacer length between the side chain and backbone, not on film thickness. Our investigation shows that in the case of the ultrathin film geometry, the glass transition temperature exhibits an anisotropic behaviour. We find the classical kink in the temperature scan (a change in slope of the free volume vs. temperature plot) due to the thermal expansion change at Tg, in p-polarisation only, which is perpendicular to the main chain orientation. In the s-polarisation measurements (parallel to the main chains) no kink was found, only an offset in the vicinity of Tg. We attribute the anisotropic thermal behaviour to a transition, the freezing of segmental motion, in the side chains only.     

Moiré pattern induced by the electronic coupling between 1-octanol self-assembled monolayers and graphite surface

Two-dimensional self-assembly of 1-octanol molecules on a graphite surface is investigated using scanning tunneling microscopy (STM) at the solid/liquid interface. STM images reveal that this molecule self-assembles into a compact hydrogen-bonded herringbone nanoarchitecture. Molecules are preferentially arranged in a head-to-head and tail-to-tail fashion. A Moiré pattern appears in the STM images when the 1-octanol layer is covering the graphite surface. The large Moiré stripes are perpendicular to the 1-octanol lamellae. Interpretation of the STM images suggests that the Moiré periodicity is governed by the electronic properties of the graphite surface and the 1-octanol layer periodicity.     

聚苯乙烯超微粒子的STM观察

发现扫描隧道显微镜可对聚苯乙烯超微粒子进行观察。用水悬浮液及苯饱和溶液使聚苯乙烯表面溶胀后，都可得到清晰的STM像，并首次从溶胀表面的高分辨率STM像观察到高分子链的精细结构和链的镶嵌式自组装形态。