光纤基底TiNi形状记忆合金薄膜制备工艺

将TiNi基记忆合金薄膜与光纤相结合可制成智能化、集成化且成本经济的微机电系统和微传感器件.本文采用磁控溅射法在二氧化硅光纤基底上制备TiNi记忆合金薄膜,系统讨论了溅射工艺参数以及后续退火处理对薄膜质量的影响.采用自研制光纤镀膜掩膜装置在直径为125μm的光纤圆周表面上形成均匀薄膜.实验表明:在靶基距、背底真空度、Ar气流量和溅射时间一定的条件下,溅射功率存在最佳值;溅射压强较大时,薄膜沉积速率较低,但薄膜表面粗糙度较小.进行退火处理后,薄膜形成较良好的晶体结构,Ti_49.09Ni_50.91薄膜中马氏体B19′相和奥氏体B2相共存,但以B19′为主.根据本文研究结果,在玻璃光纤基底上制备高质量的TiNi基记忆合金薄膜是可实现的,本工作为下一步研制微机电系统和微型传感器做了基础准备.     

TBOR-shaped electro-optic modulator with dual output based on double-layer graphene

We proposed an electro-optic modulator with two-bus one-ring (TBOR) structure to improve the extinction ratio and reduce insert loss. It has a dual output compared with one-bus one-ring structure. In addition, double-layer graphene makes it possible for the modulation in the visible to mid-infrared wavelength range. It shows that this new electro-optic modulator can present two switching states well with low insertion loss, high absorption and high extinction ratio. At $\lambda =1550\text{ nm}$, when the switching states are based on the chemical potential, ${\mu }_{\mathrm{c}}=0.38\text{ eV}$ and ${\mu }_{\mathrm{c}}=0.4\text{ eV}$, the insertion losses of both output ports are less than 2 dB, the absorption of the output port coupled via a micro-ring reaches 45 dB and the extinction ratio reaches 14 dB. When the refractive index of the dielectric material is 4.2, the applied voltage will be less than 1.2 V, thus can be used in low-voltage CMOS technology.     

The direct architecture of carbon fiber‐carbon nanofiber hierarchical reinforcements for superior interfacial properties of CF/epoxy composites

A simple and efficient chemical method was developed to graft directly carbon nanofibers (CNFs) onto carbon fiber (CF) surface to construct a CF‐CNF hierarchical reinforcing structure. The grafted CF reinforcements via covalent ester linkage at low temperature without any usage of dendrimer or catalyst was investigated by FTIR, X‐ray photoelectron spectroscopy, Raman, scanning electron microscopy, atomic force microscopy, dynamic contact angle analysis, and single fiber tensile testing. The results indicated that the CNFs with high density could effectively increase the polarity, wettability, and roughness of the CF surface. Simultaneous enhancements of the interfacial shear strength, flexural strength, and dynamic mechanical properties as well as the tensile strength of CFs were achieved, for an increase of 75.8%, 21.9%, 21.7%, and 0.5%, respectively. We believe the facile and effective method may provide a novel and promising interface design strategy for next‐generation advanced composite structures.     

Pseudapenes A–C,sesquiterpenoids from the marine-derived fungus Pseudallescheria apiosperma F52-1

Three sesquiterpenoids pseudapenes A–C (1–3) were isolated from the marine-derived fungus Pseudallescheria apiosperma F52-1. Pseudapene A (1) has an unprecedented 2-methyl-5-methylene-3-(2-methylbut-2-ene)-dicyclo(3, 3, 0)-octane carbon skeleton and pseudapenes B (2) and C (3) possess an unique 2-methyl-4-methylene-2-(2-methylpent-2-ene)-dicyclo(3, 2, 0)-heptane chemical scaffold. Their structures were determined by use of MS and NMR spectroscopic data, and ECD, optical rotation and ¹³C NMR calculations.     

Mechanical Properties Comparison of Various Ratios of L-Lactide Grafted Sisal Fibers and Untreated Sisal Fibers Reinforced Poly (lactic acid) Composites

Composites composed of the mixed fibers of L-lactide (LA) grafted sisal fiber (SF-g-LA) and untreated sisal fiber (USF) in a poly (lactic acid) (PLA) matrix were prepared with SF-g-LA/USF fibers ratios of 0, 1:9, 3:7, 5:5, 7:3, 9:1, and 1. The mechanical properties and the interfacial performance of the mixed SF reinforced PLA composites were investigated. The results of the study showed that the introduction of SF-g-LA improved the tensile strength, tensile modulus, flexural strength and flexural modulus of the mixed SF reinforced PLA composites compared with pure PLA or PLA composites with only USF, resulting from the improved interfacial adhesion between SF-g-LA and the PLA matrix. In addition, the introduction of some amount of USF enhanced the reinforcing efficiency of the mixed SF in the composites compared to the PLA composites with only SF-g-LA, owing to the good mechanical properties of USF itself. Furthermore, as for the tensile strength and tensile modulus of the mixed SF reinforced PLA composites, the optimal ratio of SF-g-LA and USF was 7:3, whereas for the flexural modulus of the mixed SF reinforced PLA composites, the optimal mixed ratio of SF-g-LA and USF was 3:7.     

碳纤维复合材料的激光清洗等离子体光谱在线检测研究

近年来碳纤维复合材料（CFRP）由于性能优异，受到工业领域广泛关注。采用激光清洗技术预处理碳纤维复合材料表面的污染物和环氧树脂等杂质，有利于改善碳纤维复合材料表面性能，提高碳纤维复合材料胶接界面的结合强度。在线检测激光清洗过程，实时判断碳纤维复合材料的表面清洗质量，是保证激光清洗效果的关键环节，也是激光清洗装置自动化、集成化的核心技术。激光诱导等离子体光谱技术可以快速分析材料表面元素变化，实现在线检测激光清洗表面状态，在激光清洗领域有很广的应用前景。采用Nd∶YAG高能量脉冲激光器产生的1 064 nm激光在空气环境中诱导产生等离子体，利用改进型光栅光谱仪(ME5000)获取等离子体光谱，在线检测激光清洗碳纤维复合材料。研究外界空气环境对等离子体光谱检测结果的影响，发现350~700 nm波段的元素谱线可用于碳纤维复合材料表面物质成分分析；采用电子扫描显微镜观测的激光清洗表面形貌和X射线电子能谱仪测得的元素变化共同表征等离子体光谱检测的有效性，通过采集不同激光能量以及不同作用次数的等离子体光谱图，获得碳纤维复合材料表层树脂物质通过激光单次清洗干净的阈值，研究激光清洗质量与激光诱导等离子体谱线成分及其强度变化的关系。结果表明：在获取的激光诱导等离子体光谱中，光谱图中谱线波长在393.3 nm的S(Ⅱ)和589.5 nm的S(Ⅱ)谱线可有效在线表征碳纤维复合材料表面清洗质量；激光单次去除干净表面环氧树脂的阈值为10.68 mJ；低激光能量时需要清洗多次可以去除干净表面树脂；高激光能量时清洗单次可使表面树脂去除干净，多次清洗易造成基体损伤。实验结果为激光清洗碳纤维复合材料的智能集成化应用提供工艺依据和技术支持。     

Recent advances in photofunctional polymorphs of molecular materials

Recently, molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors, lighting display, and cell imaging. Crystalline polymorph is an intriguing phenomenon that the presence of multiple packing and aggregate architectures of the same molecular system. The studies on polymorphs for molecule-based fluorophores provide the opportunities to adjust the mode of molecular packing and photophysical properties, which will help to illustrate the structure-property relationship. In this review, we focus on the recent progress in various feasible methods of molecule-based crystalline polymorphism growth and their adjustable photofunctional properties, which will open up possibilities of variant optical applications. Firstly, several effective ways to prepare and screen polymorphs are sorted out. And then, we discuss the discrepant properties and multifunctional applications (such as sensors, laser, and OFET, etc.). Finally, the development trends and future prospects of these polymorphs are also briefly introduced.     

氮化硼纳米管-纳米片分级结构的制备及光学和吸附特性

将五硼酸铵、 氨硼烷络合物和氧化镁混合, 球磨均匀后, 在1200 ℃及0.6 L/min流动氨气保护条件下退火6 h, 即可在氧化铝基片上收集到白色毛状产物. 采用X射线衍射(XRD), 红外光谱(FTIR)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 拉曼光谱(Raman)、 紫外-可见吸收光谱(UV-Vis)和荧光光谱(PL)对产物进行了表征. 结果表明, 样品呈一维线状分级结构, 长度大于5 mm, 中间为竹节状空心结构, 内部管径为50~350 nm, 外径范围为200~800 nm. 分级结构表面负载了大量氮化硼(BN)纳米薄片, 单个薄片厚度约为13 nm. 薄片弯曲褶皱, 相互交织, 构成1个氮化硼片层, 其厚度约为50~200 nm. UV-Vis和PL光谱测试结果表明, 氮化硼纳米管(BNNT)分级结构在紫外光材料领域具有一定的应用潜力, 且对亚甲基蓝具有良好的吸附能力(7 min即可吸附71%, 107 min时可吸附96%). 对比实验结果表明, BNNT的生长机理遵循气-液-固相(VLS)模型, 而表面负载的超薄BN片的生长机理遵循气-固相(VS)模型.     

Ultrastretchable and conductive core/sheath hydrogel fibers with multifunctionality

Conductive hydrogels with ionic compounds possess great potential for the development of soft smart devices. A dielectric scarfskin is typically required for these devices to prevent short circuiting, leading to devices with lower stretchability than the hydrogel. Henceforth, commonly used dielectric materials, such as PDMS and Ecoflex, cannot be largely stretched. Hydrogel devices with ultrastretchability are required to accommodate hostile application environments. Herein, we propose a hydrogel fiber coated with a dielectric layer that can be stretched to over 2000% of its initial length. The fiber remains conductive when stretched to ~1300%. In addition, the core/sheath hydrogel fiber can be endowed with a variety of functional properties, such as electroluminescence (EL), photoluminescence (PL), and magnetic‐responsiveness, demonstrating scalability of the resultant fiber. The present work can pave the way for numerous next‐generation soft devices, such as smart textiles and wearable electronics. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 272–280