含联苯基团侧链聚酰亚胺液晶取向膜的研究

制备了含联苯液晶基元侧链的三种聚酰亚胺(C 6-DABBE/ODPA,C 2-DABBE/ODPA和DABBE/ODPA),并进行了表面摩擦取向,用偏光显微镜(POM)、原子力显微镜(AFM)等方法对取向膜诱导液晶分子取向能力和打磨后取向膜的微观形貌进行了考察,研究了预倾角与摩擦强度,固化温度的依赖关系。结果表明,含6个亚甲基柔性间隔基的C 6-DABBE/ODPA取向膜对液晶分子有很好的取向能力,能获得10°以上的预倾角。打磨后的取向膜表面出现了约30 nm深的沟槽。且取向方向与打磨方向一致;随着摩擦强度的增大,预倾角呈减小的趋势;随着固化温度的升高,酰亚胺化程度提高,取向膜的预倾角也随之增大;在230℃对取向膜进行退火处理,能明显改善其取向性能。     

系列有机硅改性紫外光-热混杂固化树脂的表面性能

以有机硅改性丙烯酸环氧单酯为树脂配制了一系列紫外光-热混杂固化体系,用红外光谱(FT-IR)表征了固化过程特征吸收峰的变化;测试了有机硅链段的长短对固化膜表面水接触角、表面能和硅元素分布的影响。结果表明,在相同稀释剂条件下,丙烯酸环氧单酯光-热固化膜的表面水接触角为62.53°,表面能为47.62 mN/m,有机硅改性丙烯酸环氧单酯体系光-热固化膜的表面水接触角最高可达106.75°,相应的表面能为18.62 mN/m。有机硅改性体系中随着有机硅链段的增长,固化膜表面水接触角和表面硅元素含量逐渐增加,表面能则逐渐下降,表面元素分析也显示固化膜表面硅元素含量要比背面的高。     

系列有机硅改性紫外光-热混杂固化树脂的表面性能EI北大核心CSCD

以有机硅改性丙烯酸环氧单酯为树脂配制了一系列紫外光-热混杂固化体系,用红外光谱(FT-IR)表征了固化过程特征吸收峰的变化;测试了有机硅链段的长短对固化膜表面水接触角、表面能和硅元素分布的影响。结果表明,在相同稀释剂条件下,丙烯酸环氧单酯光-热固化膜的表面水接触角为62.53°,表面能为47.62 mN/m,有机硅改性丙烯酸环氧单酯体系光-热固化膜的表面水接触角最高可达106.75°,相应的表面能为18.62 mN/m。有机硅改性体系中随着有机硅链段的增长,固化膜表面水接触角和表面硅元素含量逐渐增加,表面能则逐渐下降,表面元素分析也显示固化膜表面硅元素含量要比背面的高。     

UV固化含氟聚丙烯酸酯的制备

以甲基丙烯酸十二氟庚酯、丙烯酸-2-乙基己酯、甲基丙烯酸羟乙酯、苯乙烯为聚合单体,偶氮二异丁腈为引发剂,通过溶液聚合制得了含氟羟基聚丙烯酸酯共聚物(PGHES),以含异氰酸酯的不饱和单体HIp与共聚物PGHES侧链上的羟基反应制得光敏性含氟聚丙烯酸酯(U-PGHES)。用傅立叶红外光谱(FT-IR)、核磁共振氢谱(1 H-NMR)表征聚合物结构;用凝胶渗透色谱(GPC)及差示扫描量热仪(DSC)表征聚合物分子量及玻璃化转变温度;用光学接触角测量仪测量了聚合物固化膜接触角并计算得到表面能。结果表明,固化膜表面能随U-PGHES中含氟量的增加而降低,当含氟量达到9%时,表面能降低趋缓。     

PS-b-PMTFPS/PS共混聚合物的接触角和表面张力

通过测定水和甘油在PS-b-PM TFPS/PS共混聚合物膜表面接触角的变化,发现在聚合物中引入少量含氟聚硅氧烷链段可以明显提高聚合物膜的憎水、憎油性,当含氟链段含量仅0.39%时,表面张力达到15.69×10-3N/m,显示出明显的低表面能特征。而热处理能有效地增强这一效果,在含氟链段含量较低时尤其明显。     

液晶性π-共轭聚合物的研究进展

具有液晶性的冗．共轭聚合物是近年来新兴的研究课题。π-共轭聚合物的刚性主链能作为介晶单元使其具有液晶性；另外，侧链上带有介晶单元的π-共轭聚合物也能显示出液晶性。这类具有液晶性的聚合物，在液晶态下极易通过拉伸、电场或磁场下获得链的取向。许多与π-电子离域有关的物理性能（导电性、三阶非线性光学性和电致变色性等）都会由于链在液晶态下的取向而增强。     

VUV辐射改性PET对液相沉降聚合PEDOT/PET透明导电膜的影响

以172nm真空紫外(VUV)照射聚对苯二甲酸乙二醇酯(PET)膜,再浸入Fe(OTs)3溶液吸附Fe(OTs)3和浸入3,4-乙撑二氧噻吩(EDOT)溶液引发EDOT在PET表面原位聚合,制备透明导电膜。以红外光谱、水接触角和碘量法分析照射时间对PET表面组成、浸润性和吸附性的影响;以紫外-可见分光光谱分析PEDOT的结构;以四探针测定表面电阻;研究VUV辐射对产物透明性和导电性的影响。VUV辐射在PET表面能引入羧基等含氧基团,提高PET的浸润性和吸附性。经4min辐射,水接触角从75°降到30°,Fe(OTs)3吸附量从0.9mmol/m2增加到1.3mmol/m2;经EDOT溶液浸渍,掺杂的PEDOT覆盖PET,使PET变为导电膜。VUV照射4min,所得复合膜的表面电阻可低于900Ω/□,透光率达80%。     

热塑性聚氨酯弹性体表面接触角测量及粘合性能分析

通过接触角法研究了推进剂用普通热塑性聚氨酯弹性体(BTPU)和改性后的热塑性聚氨酯弹性体(DTPU)粘合剂的表面性能,并通过进一步的分析比较了二者与推进剂中的高能硝胺黑索今(RDX)的相互作用大小,结果表明,DTPU的表面能(40.55mJ/m2)大于BTPU(34.59mJ/m2),DTPU与RDX的粘附功为81.83mJ/m2,BTPU与RDX的粘附功为72.30mJ/m2,DTPU与固体推进剂中RDX的粘结能力好于BTPU,更适用于用作固体推进剂的粘结剂。     

利用偏振激光使液晶取向

据美国HercuIes Inc.公司的研究人员报道,他们采用偏振激光这一新方法使液晶取向。在典型的液晶显示器件中,装有液晶的小室内表面涂敷一层用机械方法摩擦过的聚合物膜。该聚合物膜能使棒状液晶分子按摩擦方向取向。这种取向结构可用电的方法改变,同时改变了器件的光学性能。该公司的研究人员发明了一种不同类型的小室。在小室中一面涂敷摩擦过的聚酰亚胺;另一面涂敷摩擦过的掺有染料的聚酰亚胺。在相交的偏振片之间观察时,小室中取向了的液晶物质呈暗色。该小室经与初始取向方向平行的偏振激光照射,会使掺有染     

辐射交联聚甲基乙烯基硅氧烷-聚乙烯合金膜的XPS研究

用机械共混或溶液共混的方法,制备了γ-射线辐照交联的聚甲基乙烯基硅氧烷(PDMVS)-聚乙烯(PE)合金膜,并用 XPS,SEM 和接触角测量等研究其表面结构。XPS 结果表明,在深度～5nm 的膜表面有 PDMVS 链段的富集(只有一个例外),并得到接触角测量的支持。研究结果也表明,即使在～5nm 范围的表面有 PE 链段的富集,其最外层也存在一层很薄(～单分子层)的PDMVS,这一薄层就决定了接触角,并对膜功能有大的影响。     

含氟硅低表面能共聚物的制备与表征

将丙烯酸六氟丁酯和γ-甲基丙烯酰氧基丙基三甲氧基硅烷与(甲基)丙烯酸(酯)进行共聚,合成含氟硅共聚物.用红外光谱(FT-IR)、X射线光电子能谱(XPS)和热重分析(TGA)对共聚物的结构和性能进行表征,并测试了共聚物膜的吸水率及对水和油的接触角.XPS结果表明,共聚物膜表面的F和Si元素相对物质的量明显高于150 n...     

阴极真空弧源沉积氟化类金刚石薄膜的结构与性能研究

采用脉冲磁过滤阴极真空弧源沉积系统(FCVA)在单晶硅基片上制备了含氟量不同的一系列氟化类金刚石膜(a-C:F).重点研究了氟掺杂对非晶态碳基薄膜结构、机械性能和疏水性能的影响.薄膜的成分和结构采用X射线光电子能谱仪(XPS)和激光拉曼光谱(Raman)进行了表征,薄膜表面形貌和粗糙度采用原子力显微镜(AFM)进行了分析.使用纳米压痕仪测量了薄膜硬度,纳米划痕仪测量了膜基结合力.采用躺滴法测量薄膜与双蒸水之间的接触角来评价其疏水性能.结果表明,随着CF4流量的逐渐增加,薄膜的氟化程度逐渐增强,膜中最大氟含量达45.6 at%;薄膜呈典型的类金刚石状结构,但薄膜的无序化程度增强;由于-CFn+的刻蚀,薄膜表面更加致密化、粗糙度逐渐减小.薄膜的机械性能良好,硬度在12GPa以上.薄膜的疏水性能得到增强,与双蒸水之间的最大接触角达106°,接近于聚四氟乙烯(PTFE,110°).     

Electrical contact properties between the accumulation layer and metal electrodes in ultrathin poly(3-hexylthiophene)(P3HT) field effect transistors

Probing contact properties between an ultrathin conjugated polymer film and metal electrodes in field effect transistors (FETs) is crucial not only to understanding charge transport properties in the accumulation layer but also in building organic sensors with high sensitivity. We investigated the contact properties between gold electrodes and poly(3-hexylthiophene) (P3HT) as a function of film thickness using gated four-point sheet resistance measurements. In an FET with a 2 nm thick P3HT film, a large voltage drop of 1.9 V (V(D) = -3 V) corresponding to a contact resistance of 2.3 × 10(8) Ω was observed. An effective FET mobility of 1.4 × 10(-3) cm(2)/(V s) was calculated when the voltage drop at the contacts was factored out, which is approximately a factor of 3 greater than the two-contact FET mobility of 5.5 × 10(-4) cm(2)/(V s). A sharp decrease in the ratio of the contact resistance to the channel resistance was observed with increasing film thickness up to a thickness of approximately 6 nm, separating a contact limited regime from a charge transport limited regime. The origin of the large contact resistance observed in the device prepared with an ultrathin P3HT film is discussed in light of results from X-ray diffraction (XRD) and atomic force microscopy (AFM) studies.     

Geometrically tuned and chemically switched wetting properties of silicon nanotips

The wetting properties of silicon nanotips (SiNTs) are discussed. SiNTs were prepared by single step dry etching of silicon wafers in an electron cyclotron resonance plasma of silane, methane, argon and hydrogen and water contact angles were measured as a function of their aspect ratio (α) and the inter-tip distance. The hydrophilic nature of the SiNTs is tunable with α and the inter-tip distance. Super-hydrophilicity with water contact angles close to 2° was observed with α>12 (length ～1500?nm). Upon coating a 1500?nm long SiNT with TiO(2), the water contact angle jumped from 2° to ～140°, demonstrating a switchover from super-hydrophilic to hydrophobic surface properties.     

丙纶和涤纶集尘极表面的液滴浸入扩散动力学特性

为揭示冲洗水流经丙纶、涤纶集尘极表面浸入扩散过程的一般规律, 解决传统湿式静电技术由集尘极材料选择及表面水膜布置不均引发的系列问题, 利用高速摄像系统测量不同体积和性质的液滴在丙纶纤维织物(840A)和涤纶纤维织物(728)表面扩散面积和液滴高度随时间的变化关系, 得到液滴浸入扩散动力学特性。结果表明: 水液滴与840A的接触角θ为136.2°, 与728的θ为52.5°, 乙醇液滴与840A的θ为41.9°, 与728的θ为46.5°; 液滴扩散可分为扩散初期和后期两个阶段; 水、乙醇液滴在728表面的扩散形状均为椭圆, 扩散过程分别符合ExpAssoc、Hill分布; 水、乙醇液滴在840A表面的扩散形状为圆和椭圆, 乙醇液滴扩散过程符合Hill分布; 织物表面纹理结构、液滴体积和性质、织物厚度、材料表面自由能对液滴扩散过程有明显影响。      

Synthesis and photoluminescent properties of nanocrystalline CaMoO4 thin film via chemical solution processing

Stoichiometric CaMoO4 thin film was successfully fabricated based on chemical solution processing. The thin films were deposited on Si(100) substrates by means of the spin-coating technique. X-ray diffraction reveals that the CaMoO4 thin film prepared are pure and well crystalline thin films. Atom Force Microscope photographs indicate that the film prepared possesses a homogeneous and dense surface morphology. The average grain size of the films was 40-50 nm, and the root-mean-square (RMS) of the surface roughness and the average surface roughness of the film measured were 2.161 nm and 1.726 nm respectively. The photoluminescent properties of calcium molybdate thin film under ultraviolet light excitation were systematically measured from 12 K to room temperature and a green emission band of the films were observed. The results of present work confirm that the chemical solution processing is a promising technology on the fabrication of CaMoO4 thin film.     

Surface tension of liquid Cu and anisotropy of its wetting of sapphire

Precise surface tension data of liquid Cu are fundamental for studying its interaction with differently oriented single crystalline sapphire surfaces. For this reason, the surface tension of liquid Cu was measured covering a wide temperature interval of 1058 °C ≤ T ≤ 1413 °C. To avoid contamination of the sample from contact with container walls, the measurement was performed contactlessly in an electromagnetic levitation furnace using the oscillating drop method. A fast digital CMOS-camera (400 fps) recorded top view images of the oscillating sample. From an analysis of the frequency spectrum the surface tension was determined. The measured surface tension of Cu was used to calculate interfacial energies from contact angles of liquid Cu droplets, deposited on the C(0001), A(11-20), R(1-102) and M(10-10) surfaces of sapphire substrates. These were measured by means of the sessile drop method at 1100 °C using a drop dispenser. Within the first minutes of contact with the sapphire substrates, the contact angles of liquid Cu droplets rise to their equilibrium values. From these, in addition to interfacial energies also works of adhesion were determined.     

Relationships between water wettability and ice adhesion

Ice formation and accretion may hinder the operation of many systems critical to national infrastructure, including airplanes, power lines, windmills, ships, and telecommunications equipment. Yet despite the pervasiveness of the icing problem, the fundamentals of ice adhesion have received relatively little attention in the scientific literature and it is not widely understood which attributes must be tuned to systematically design "icephobic" surfaces that are resistant to icing. Here we probe the relationships between advancing/receding water contact angles and the strength of ice adhesion to bare steel and twenty-one different test coatings (～200-300 nm thick) applied to the nominally smooth steel discs. Contact angles are measured using a commercially available goniometer, whereas the average strengths of ice adhesion are evaluated with a custom-built laboratory-scale adhesion apparatus. The coatings investigated comprise commercially available polymers and fluorinated polyhedral oligomeric silsesquioxane (fluorodecyl POSS), a low-surface-energy additive known to enhance liquid repellency. Ice adhesion strength correlates strongly with the practical work of adhesion required to remove a liquid water drop from each test surface (i.e., with the quantity [1 + cos θ(rec)]), and the average strength of ice adhesion was reduced by as much as a factor of 4.2 when bare steel discs were coated with fluorodecyl POSS-containing materials. We argue that any further appreciable reduction in ice adhesion strength will require textured surfaces, as no known materials exhibit receding water contact angles on smooth/flat surfaces that are significantly above those reported here (i.e., the values of [1 + cos θ(rec)] reported here have essentially reached a minimum for known materials).     

Effect of ZrO2 on the alkali feldspar-aluminosilicate interface

The contact angles of the alkali feldspars containing 0, 4, 8 and 12 vol % ZrO₂ on the aluminosilicate substrate were measured by sessile drop method. During the heating from 1350 to 1520° C and the holding at 1350° C, the contact angles were generally increased with increasing ZrO₂ content. 8 vol % ZrO₂ in the melt drop was very effective to raise the contact angles and 12 vol % ZrO₂ was barely sufficient to maintain the contact angles at around 90° or larger at elevated temperatures. The SEM micrographs indicated that ZrO₂ particles were scattered throughout the drop and also located in the interface between the drop and substrate. The dissolution of the substrate by liquid feldspar and the diffusion of ZrO₂ in the substrate were also observed. The cause of the increase in contact angle with increasing ZrO₂ content are discussed.     

酸碱处理对聚酰亚胺薄膜的表面改性

采用酸碱处理的方法对聚酰亚胺(PI)薄膜表面改性。利用万能试验机和热失重仪考察了处理前后PI薄膜力学性能和热性能的变化情况,并通过傅立叶红外光谱仪、原子力显微镜及视频接触角仪对PI薄膜改性前后表面性能进行了表征。结果表明,经酸碱处理后,PI薄膜表面化学组成和表面形貌均发生变化,表面亲水性增大;当处理时间为4min时,力学性能保持在97%以上,热稳定性略有下降;均方根粗糙度从1.057nm增大到3.002nm,接触角从77.32°下降到46.70°,粘接功提高了38.20%。