基材与液晶种类对液晶复合膜血液相容性的影响

从仿生学的角度设计和制备结构及组成与生物膜及血管内壁相似的聚合物/液晶复合膜,作为新一类抗凝血生物材料,并通过血液相容性试验考察复合材料的抗凝血性能.结果显示:不同基材及液晶种类的聚合物/液晶复合膜,其溶血率值均小于5%,符合生物材料溶血试验的要求;复合膜的动态凝血性能取决于基材与液晶两者之间的兼容性及配比,动态凝血性能较佳的复合膜表面粘附的血小板大多呈单个粘附状态,数量较少,且基本无变形,呈现出良好的血液相容性.     

液晶性能对聚氨酯／液晶复合膜抗凝血性能的影响

合成了3种亲水性胆甾醇液晶化合物,HO-[CH2CH2]-nO-C∧‖O-O-Chol（n=2,3,4）,用元素分析法、红外光谱、差热分析以及偏光显微镜观察对其结构进行了表征,利用聚氨酯与上述液晶化合物制备复合膜,研究了液晶性能对聚合物/液晶复合膜抗凝血性能的影响,结果表明,胆甾醇液晶化合物有利于改善聚合物材料的抗凝血性能。     

Photorefractivity in polymer dissolved liquid crystal composites composed of low-molecular-weight nematic liquid crystals and copolymer comprising mesogenic side groups

This paper describes the photorefractive effect of the liquid crystalline composite materials comprising low-molecular-weight nematic liquid crystals (L-LC), copolymer with mesogenic side groups and a small amount of photosensitizer. Copolymers with four kinds of mesogenic side groups were investigated with respect to the compatibility between the L-LC and the copolymer and the photorefractivity of the composites. Two of them could be miscible with L-LC and the composite exhibited LC phase even though the copolymer itself did not show a LC phase. High gain coefficients (> cm^K1) under the low applied dc electric field (<1V/mm) was observed when the composites showed a mesophase without any macroscopic phase separation.     

Photorefractivity in polymer dissolved liquid crystal composites composed of low-molecular-weight nematic liquid crystals and copolymer comprising mesogenic side groups

This paper describes the photorefractive effect of the liquid crystalline composite materials comprising low-molecular-weight nematic liquid crystals (L-LC), copolymer with mesogenic side groups and a small amount of photosensitizer. Copolymers with four kinds of mesogenic side groups were investigated with respect to the compatibility between the L-LC and the copolymer and the photorefractivity of the composites. Two of them could be miscible with L-LC and the composite exhibited LC phase even though the copolymer itself did not show a LC phase. High gain coefficients (>200 cm⁻¹) under the low applied dc electric field (<1 V/μm) was observed when the composites showed a mesophase without any macroscopic phase separation.     

Magnetic-field-assisted formation of alignment polymer coatings in liquid crystal cells

We describe a new method for obtaining liquid crystal (LC) layers with planar orientation in plane-parallel cells, which is based on the technology of LC-polymer interface formation in solution under the action of an applied magnetic field. The azimuthal anchoring energy of LC at the polymer surface has been determined by measuring the angle of orientation of the nematic LC director on the substrate surface as a function of the magnetic field. The LC orientation provided by the proposed method is stable, and the anisotropy of LC anchoring is comparable with that achieved using well-known methods of alignment polymer film preparation by rubbing.     

Artificial muscles based on liquid crystal elastomers

This paper presents our results on liquid crystal (LC) elastomers as artificial muscle, based on the ideas proposed by de Gennes. In the theoretical model, the material consists of a repeated series of main-chain nematic LC polymer blocks, N, and conventional rubber blocks, R, based on the lamellar phase of a triblock copolymer RNR. The motor for the contraction is the reversible macromolecular shape change of the chain, from stretched to spherical, that occurs at the nematic-to-isotropic phase transition in the main-chain nematic LC polymers.We first developed a new kind of muscle-like material based on a network of side-on nematic LC homopolymers. Side-on LC polymers were used instead of main-chain LC polymers for synthetic reasons. The first example of these materials was thermo-responsive, with a typical contraction of around 35-45% and a generated force of around 210 kPa. Subsequently, a photo-responsive material was developed, with a fast photochemically induced contraction of around 20%, triggered by UV light.We then succeeded in preparing a thermo-responsive artificial muscle, RNR, with lamellar structure, using a side-on nematic LC polymer as N block.Micrometre-sized artificial muscles were also prepared. This paper illustrates the bottom-up design of stimuli-responsive materials, in which the overall material response reflects the individual macromolecular response, using LC polymer as building block.     

新型液晶对其与聚硅氧烷复合膜抗凝血性能的影响

本研究合成出三种胆甾型液晶化合物,并用IR和DSC进行了表征.将三种液晶化合物与聚硅氧烷制成复合膜,测定其抗凝血性能,结果表明,亲水性愈高的复合膜血液相容性愈好.     

壳聚糖-明胶液晶复合支架性能

液晶态普遍存在于生物体中,为开发新型生物支架材料和更好地模拟生物体内微环境,从仿生角度出发,制备出壳聚糖-明胶液晶复合支架;采用偏光显微镜、扫描电镜和分析天平分别表征了其织构和形态、孔隙率和吸水性。实验结果表明,壳聚糖-明胶质量比为7:3液晶支架呈现典型的胆甾相液晶织构,孔隙率和吸水性分别在95%和85%左右;其性能优于其他配比的液晶复合支架。     

Characterization of optically switchable holographic polymer-dispersed liquid crystal transmission gratings

This study characterizes the all-optical switching effect in holographic polymer-dispersed liquid crystal transmission gratings. The light-induced switching behaviors of these structures are due to the doped azobenzene-derived LC (azo-LC), which changes the refractive index of phase-separated LC within the polymer composite. This study also optimizes the polymer-dispersed liquid crystal formulation containing 15 wt.% azo-LC and 35 wt.% nematic LC to achieve a grating performance with a tunable diffraction efficiency of 78% and a fast switching-on time (0.5 s) with a relatively small light stimulus of 9 mW/cm².     

A functionally separated nanoimprinting material tailored for homeotropic liquid crystal alignment

In order to homeotropically align liquid crystals (LCs) at the nanosized surface grooves processed by nanoimprint lithography technology (NIL), we propose to design a hybrid-type homeotropic polymer material consisting of two distinct moieties with largely different thermo-mechanical properties and surface activity. Surface contact angle measurements and sum-frequency vibrational spectroscopy allow us to conclude that the polymer film is a functionally separated composite suitable for the homeotropic LC alignment processed by NIL. As one of the potential applications using the hybrid-type homeotropic polymer, we demonstrate that the nanoimprinted grooves at the polymer surface can achieve a zenithal nematic LC bistability.     

羟基磷灰石对硅橡胶复合材料抗凝血性能的影响

本研究制备了在165℃×10min条件下交联的机械共混羟基磷灰石和硅橡胶生物材料,并通过动态凝血试验、溶血率测定、血小板粘附的SEM观察等方法评价了羟基磷灰石与硅橡胶复合材料的血液相容性.结果表明,含60%羟基磷灰石的复合材料血液相容性最佳.     

Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

A facile approach to modify silicone rubber (SR) membrane for improving the blood compatibility was investigated. The hydrophobic SR surface was firstly activated by air plasma, after which an initiator was immobilized on the activated surface for atom transfer radical polymerization (ATRP). Three zwitterionic polymers were then grafted from SR membrane via surface-initiated atom transfer radical polymerization (SI-ATRP). The surface composition, wettability, and morphology of the membranes before and after modification were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (WCA) measurement, and atomic force microscopy (AFM). Results showed that zwitterionic polymers were successfully grafted from SR surfaces, which remarkably improved the wettability of the SR surface. The blood compatibility of the membranes was evaluated by protein adsorption and platelet adhesion tests in vitro. As observed, all the zwitterionic polymer modified surfaces have improved resistance to nonspecific protein adsorption and have excellent resistance to platelet adhesion, showing significantly improved blood compatibility. This work should inspire many creative uses of SR based materials for biomedical applications such as vessel, catheter, and microfluidics.     

膜材料的合金化改性

聚合物材料合金化是改善膜性能,拓宽膜材料使用范围的一种简便而有效的手段.文中对聚合物材料合金化对膜的一些物理化学性质的影响进行了探讨;并讨论了聚合物材料合金化对膜结构及膜的渗透性和选择性的影响.     

Fabrication of flexible polymer dispersed liquid crystal films using conducting polymer thin films as the driving electrodes

Conducting polymers exhibit good mechanical and interfacial compatibility with plastic substrates. We prepared an optimized coating formulation based on poly(3,4-ethylenedioxythiophene) (PEDOT) and 3-(trimethoxysilyl)propyl acrylate and fabricated a transparent electrode on poly(ethylene terephthalate) (PET) substrate. The surface resistances and transmittance of the prepared thin films were 500-600 Ω/□ and 87% at 500 nm, respectively. To evaluate the performance of the conducting polymer electrode, we fabricated a five-layer flexible polymer-dispersed liquid crystal (PDLC) device as a PET-PEDOT-PDLC-PEDOT-PET flexible film. The prepared PDLC device exhibited a low driving voltage (15 VAC), high contrast ratio (60:1), and high transmittance in the ON state (60%), characteristics that are comparable with those of conventional PDLC film based on indium tin oxide electrodes. The fabrication of conducting polymer thin films as the driving electrodes in this study showed that such films can be used as a substitute for an indium tin oxide electrode, which further enhances the flexibility of PDLC film.     

羽毛角蛋白/PVA复合纳米纤维膜的制备及表征

以羽毛角蛋白(FK)和聚乙烯醇(PVA)为原料,水为溶剂,通过静电纺丝技术制备了FK/PVA复合纳米纤维膜.探讨了复合纳米纤维中FK与PVA的相容性,研究了FK的添加对纤维膜微观形貌、结晶度、热稳定性、亲水性等性能的影响.SEM结果表明,在聚合物总质量分数为14％的条件下制备的FK/PVA复合纳米纤维,表面平整光滑,平均直径为250～320 nm,FK含量越大,直径越小.FTIR结果表明,FK与PVA具有良好的相容性,分子间存在氢键作用力.XRD结果表明,FK的加入破坏了PVA分子的规整排列,复合纳米纤维膜的结晶度下降.TG分析与接触角测试结果表明,随着体系中FK配比的增大,复合纳米纤维膜的热稳定性和亲水性均得到提高.     

医用高分子复合材料

高分子复合材料的开发、利用是改善生物材料生物相容性的一条有效途径。本文首先介绍了通过高分子材料与无机物、金属、非金属碳及高分子本身复合来提高材料生物相容性研究的进展。然后,着重讨论了高分子复合材料的微相分离结构与抗凝血性能的关系。最后,概述了高分子材料和生体成分、组织的复合作用。     

SiO2/Mg（OH）2复合阻燃剂的阻燃性能研究

以SiO2/Mg(OH)2复合粉体为阻燃剂,与聚烯烃弹性体(POE)熔融共混制备了复合材料,采用灼热丝试验对其阻燃性能进行了测试,利用SEM和EDS观察POE复合材料的断面形貌、界面相容性及阻燃剂在基体中的分散行为,并对POE复合材料的力学性能进行了测试。结果表明SiO2/Mg(OH)2复合阻燃剂在POE中分散良好,界面相容性优良,具有良好阻燃效果,且可改善聚合物材料力学性能,是一种适宜推广的新型无机阻燃剂。     

Effect of the dielectric layer with photo-controllable surface relief on liquid crystal devices

We present experimental results for the dielectric layer effect on the electro-optical properties of liquid crystal (LC) devices together with numerical simulations. The photo-controllable polymer is used as a dielectric material on which the alignment agent of the LC is prepared. The surface relief structure can be induced on the dielectric polymer layer by photo-irradiation for fabricating LC microlens arrays or wide-viewing LC displays. It is found that the operation voltage of the LC device decreases with increasing the dielectric constant or with decreasing the layer thickness of the polymer. The experimental data agree well with theoretical results predicted from a simple dielectric model in the continuum theory.     

Polydimethylsiloxane (PDMS) Composite Membrane Fabricated on the Inner Surface of a Ceramic Hollow Fiber: From Single-Channel to Multi-Channel

The fabrication of a separation layer on the inner surface of a hollow fiber (HF) substrate to form an HF composite membrane offers exciting opportunities for industrial applications, although challenges remain. This work reports on the fabrication of a polydimethylsiloxane (PDMS) composite membrane on the inner surface of a single-channel or multi-channel ceramic HF via a proposed coating/cross-flow approach. The nanostructures and transport properties of the PDMS HF composite membranes were optimized by controlling the polymer concentration and coating time. The morphology, surface chemistry, interfacial adhesion, and separation performance of the membranes were characterized by field-emission scanning electron microscope (FE-SEM), attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, the nano-indentation/scratch technique, and pervaporation (PV) recovery of bio-butanol, respectively. The formation mechanism for the deposition of the PDMS layer onto the inner surface of the ceramic HF was studied in detail. The optimized inner surface of the PDMS/ceramic HF composite membranes with a thin and defect-free separation layer exhibited a high flux of ~1800 g·m⁻²·h⁻¹ and an excellent separation factor of 35–38 for 1 wt% n-butanol/water mixtures at 60 °C. The facile coating/cross-flow methodology proposed here shows great potential for fabricating inner-surface polymer-coated HFs that have broad applications including membranes, adsorbents, composite materials, and more.     

Preparation of gas separation membranes by plasma polymerization with fluoro compounds

Plasma polymerization coatings were applied for the preparation of gas separation membranes. Mainly fluoro compounds were used as coating materials. The membranes showed good separation characteristics with high flux for gaseous systems. The plasma polymerization composite parameter given by W/FM plays an important role in obtaining excellent separation characteristics. The correlation between the conversion rate DR/FM, where DR is the deposition rate of plasma polymer, and W/FM is useful to consider the plasma polymer character under the different plasma polymerization conditions (discharge power W and monomer flow rate F). The proper conditions for membrane preparation lie in the intermediate region between the region in which the monomer flow rate is deficient and that in which the discharge power is deficient. Furthermore, the plasma polymerization coatings with the higher molecular weight monomer gave the higher separation characteristics. Plasma polymer composite membranes in this study showed superiority for the molecular sieve type of separation over the solution-diffusion type of separation.