聚甲基丙烯酸接枝炭微球

以乙炔为碳源,采用化学气相沉积法,在氩气气氛下,制备了炭微球(CMSs);并用硫酸和高锰酸钾的混合溶液对CMSs进行氧化处理,使其表面引入含氧官能团;然后用KH-570对氧化CMSs进行修饰并将甲基丙烯酸(MAA)接枝于CMSs表面,制得了接枝微粒PMAA/CMSs.用场发射扫描电子显微镜、红外光谱和热重分析对产物的结构和形貌进行了表征和分析.结果表明:采用逐步接枝法成功地将MAA接枝到CMSs表面,为CMSs在聚合物基体中分散、制备功能材料提供了途径.     

碳微球的离子化表面修饰

碳微球(CMSs)经HNO3和H2O2混酸处理后,与NaOH碱溶液进行离子化反应,考察离子化反应前后CMSs表面性质的差异;通过场发射扫描电子显微镜、元素分析等对产物的形貌和表面结构进行了分析,同时还考察了产物在不同溶剂中的溶解性差异。结果表明,HNO3和H2O2混酸处理得到的CMSs-(COOH)n与NaOH溶液进行反应后,生成大量—COONa离子基团,形成了CMSs-(COONa)n,其表层出现沟壑,在水中的分散性明显改善,亲水性显著增强;然而,NaOH对未经酸处理的CMSs修饰效果欠佳,团聚现象依然严重;由于CMSs-(COONa)n强的离子性,很难在有机溶剂中分散。     

功能化碳微球能级的电化学表征

分别采用水热法和化学气相沉积(CVD)法,制备两种同粒径(约360 nm)的碳微球(CMSs),对CVD法制备的CMSs(CCMSs)用混酸溶液(浓硫酸:浓硝酸=3:1)进行酸化处理,在其表面引入含氧官能团,而水热法制备的CMSs(HCMSs)不作处理;然后在N,N′-二环己基碳二亚胺的作用下,用1,6-己二胺分别修饰两种CMSs。通过场发射扫描电子显微镜和傅里叶红外光谱仪对产物的形貌和结构进行表征分析,采用热重分析仪和电化学工作站对产物的热稳定性和能级结构进行表征分析,并用荧光分析仪对产物的光学性能进行表征分析。结果表明:两种CMSs都满足作为聚合物太阳能电池受体材料的能级要求,且胺化修饰可以提高CMSs的LUMO能级;HCMSs在形貌、溶剂中的分散性以及热稳定性等方面都优于CCMSs,比CCMSs更适合作聚合物太阳能电池的受体材料。     

等离子体增强化学气相沉积技术制备锗反蛋白石三维光子晶体

采用溶剂蒸发对流自组装法将单分散二氧化硅(SiO2)微球组装形成三维有序胶体晶体模板,以锗烷(GeH4)为先驱体气用等离子增强化学气相沉积法在350℃填充高折射率材料锗.获得了锗反蛋白石光子晶体.通过扫描电镜、X射线衍射仪对锗反蛋白石的形貌、成分、结构进行了表征.结果表明:锗在SiO2微球空隙内填充均匀,得到的锗为多晶态.锗反蛋白石光子晶体为三维有序多孔结构.等离子体增强化学气相沉积的潜在优势在于可实现材料的低温填充,从而以高分子材料为模板进行复型,得到多种结构的三维光子晶体.     

功能化碳微球能级的电化学表征

分别采用水热法和化学气相沉积（CVD）法,制备两种同粒径（约360 nm）的碳微球（CMSs）,对CVD法制备的CMSs （CCMSs）用混酸溶液（浓硫酸：浓硝酸=3：1）进行酸化处理,在其表面引入含氧官能团,而水热法制备的CMSs（HCMSs）不作处理;然后在N,N'-二环己基碳二亚胺的作用下,用1,6-己二胺分别修饰两种CMSs。通过场发射扫描电子显微镜和傅里叶红外光谱仪对产物的形貌和结构进行表征分析,采用热重分析仪和电化学工作站对产物的热稳定性和能级结构进行表征分析,并用荧光分析仪对产物的光学性能进行表征分析。结果表明：两种CMSs都满足作为聚合物太阳能电池受体材料的能级要求,且胺化修饰可以提高CMSs的LUMO能级;HCMSs在形貌、溶剂中的分散性以及热稳定性等方面都优于CCMSs,比CCMSs更适合作聚合物太阳能电池的受体材料。     

1,6-己二胺对碳微球的功能化修饰

首先采用体积比为1:3的浓硝酸和浓硫酸对碳微球(CMSs)进行氧化修饰,改善其表面活性;然后在缩合剂N,N'-二环己基碳二亚胺(DCC)的作用下,用1,6-己二胺与氧化CMSs反应,制备胺化CMSs。在胺化过程中考虑缩合剂DCC用量、反应时间和反应温度的影响。采用场发射扫描电子显微镜、热重分析仪和红外光谱仪对各阶段产物进行了形貌和结构的表征与分析。结果表明:对于0.3 g氧化CMSs,DCC用量0.3 g、反应时间36 h和反应温度110℃是胺化反应的适宜条件,所得胺化产物在弱极性溶剂乙酸乙酯和氯仿中有良好的分散性,且能与常用聚合物给体材料(聚3-己基噻吩)能级匹配,有望进一步与聚合物复合,为制备聚合物太阳能电池奠定基础。     

溶剂调控苯丙氨酸衍生物自组装结构的研究

本文利用四氢呋喃与水的不同比例来对苯丙氨酸衍生物自组装聚集体进行调控,通过扫描电子显微镜(SEM)、紫外和荧光对其自组装结果进行表征。研究了苯丙氨酸衍生物自组装过程中的溶剂效应。实现了通过改变溶剂对苯丙氨酸衍生物自组装的调控。     

正丁胺对氧化铝悬浮液及其电泳沉积的影响

悬浮液的悬浮性和颗粒带电性是决定氧化铝电泳沉积的关键因素.本文研究了正丁胺的添加对不同溶剂和表面活性剂体系下氧化铝悬浮液的悬浮性能和电泳沉积的影响.结果表明,正丁胺的加入不利于以水为溶剂的悬浮液体系的悬浮性,同时造成沉积产率下降.而在醇类溶剂中,正丁胺的加入对非离子型表面活性剂的体系的表面带电性影响较大,而对醇类为溶剂的悬浮液沉积产率并无明显影响.以PEI为表面活性剂的醇类悬浮液中加入正丁胺能有效提高悬浮性和沉积产率.     

均一孔径SiO2催化剂载体的制备

利用单分散二氧化硅微球的水悬浮液,在一定条件下蒸发自组装合成了孔径均一的SiO₂载体。采用低温氮吸附、压汞、SEM表征其孔结构及表面形态。结果表明,对于300 nm以下的单分散微球,都可以利用蒸发组装得到孔径均一的载体材料,且孔径尺寸可根据微球大小调变。实验发现蒸发组装制备的载体,其孔径分布受蒸发温度的影响较大。通过对蒸发温度的考察,发现50℃蒸发组装的样品孔径分布集中有序。     

碳微球负载Ag_3PO_4的合成与其光催化性能

以碳微球(CMSs)为载体,采用离子交换法制备了CMSs负载的磷酸银复合材料(CMSs/Ag3PO4)。对合成的CMSs/Ag3PO4复合材料的相组成、表面形貌和紫外-可见(UV-Vis)吸收光谱进行了表征,通过可见光催化降解甲基橙实验对所制备的CMSs/Ag3PO4复合材料的光催化活性进行了考察。结果表明:CMSs颗粒大小在100~200 nm,CMSs/Ag3PO4颗粒大小在200~250 nm;CMSs/Ag3PO4在可见光范围有强吸收,在可见光照射下,CMSs/Ag3PO4能有效地降解甲基橙,光照射60min对甲基橙的降解率可以达到92.5%;循环使用5次后,对甲基橙的降解率仍然保持为86.2%。     

Effects of suspension properties on the fabrication of Yb2Si2O7 coatings using electrophoretic deposition

This study examines the electrophoretic deposition of Yb₂Si₂O₇ particles on SiC substrates to produce Environmental Barrier Coatings. To prepare crack-free and homogeneous green coatings, the effect of the solvent, dispersant concentration, and pH were investigated. Ethanol provided a well-dispersed suspension and crack-free coating which was shown by sedimentation tests and microstructure analysis. The effect of the dispersant concentration was investigated with zeta potential measurement and microstructure analysis with a concentration above 0.5 g/L resulting in higher ionic strength and producing cracked and uneven coatings. The ionic strength was also associated with the powder packing density with larger indentation impressions measured for loosely packed coatings. The deposition rate depended on the suspension properties influenced coating integrity with delamination evidenced by analysing the current density drop during deposition. Sintering of the green coatings having different densities and microstructure showed their importance in the preparation of uniform and dense sintered coatings.     

Characterization of polyetheretherketone particle suspensions for electrophoretic deposition

Suspensions of polyetheretherketone (PEEK) using mixture of ethanol and isopropanol as solvent were prepared to carry out PEEK electrophoretic deposition (EPD). The rheological behavior and suspension structure of PEEK particles dispersed in co‐solvents were investigated over a range of pH values (1–10) and shear rates (γ = 10¹?3 × 10² s^?1). These PEEK suspensions generally exhibited a pseudoplastic flow behavior, indicating the occurrence of particle aggregation in the liquid medium. The maximum solids fraction (?_m) showed an estimated value of  ?_m = 2.9 wt %. Using a suspension with 3 wt % PEEK concentration, PEEK coatings on stainless steel substrates were obtained by EPD at constant voltage condition. The influence of the electrolyte conductivity on PEEK EPD from ethanol–isopropanol suspensions was studied. Experimental results showed that high‐conductivity ethanol‐based suspensions yield non‐uniform deposits, while low‐conductivity suspensions resulted in uniform coatings. The difference in the deposition behavior is due to the different pH of the suspensions and the relationship of pH with suspension conductivity. pH = 8 was the optimal value for this system in terms of deposition results. The surfaces of EPD PEEK coatings were homogenous and a qualitatively good adhesion between the PEEK deposits and the substrate was confirmed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40953.     

Electrospray Dense Suspensions of TiO2 Nanoparticles for Dye Sensitized Solar Cells

We report the feasibility of using electrospray to atomize dense suspension of nanoparticles with high solid concentrations. We demonstrate this principle through electrospraying dense suspensions of TiO₂ nanoparticles with 40 wt.% in ethylene glycol. A dye sensitized solar cell (DSSC) is fabricated by electrospray deposition and the power conversion efficiency up to 6.81% is demonstrated. This simple, one-step process can fabricate the active layer with uniform thickness and multiple length scales, including 25 nm TiO₂ nanoparticles, ～2 μm micro spherical particles, and ～20-μm-thick film. A judicious choice of drying temperature is important to ensure complete drying of suspension droplets while avoiding creation of hollow particles, because the hollow particles exhibit significantly lower carrier mobility and short circuit current. The very high solid concentration demonstrated in this work can potentially reduce the manufacturing cost of DSSC because less energy will be wasted on evaporating and/or recycling the organic solvent. In addition, because electrospray is compatible with roll-to-roll process and the yield is scalable through multiplexed electrosprays, the electrospray route is a promising and economically competitive approach for manufacturing DSSCs through spray deposition.

Copyright 2013 American Association for Aerosol Research     

Low-temperature fabrication of TiO<Subscript>2</Subscript> film on flexible substrate by atmospheric roll-to-roll CVD

Titanium dioxide (TiO₂) thin film was fabricated using titanium isopropoxide as a precursor through an atmospheric low-temperature roll-to-roll chemical vapor deposition method. TiO₂ was deposited on the PET substrate in the temperature range of room temperature to 100°C, and the working pressure was 740 Torr. The surface morphology of TiO₂ thin film was analyzed by field emission scanning electron microscopy and a 2D surface profiler. The results revealed that the growth rate of TiO₂ film was 31 nm/min at 100°C, and it also showed that the surface is uniform and smooth. Moreover, the lowest root mean square roughness (R _q) value of 1.87 nm was obtained for TiO₂ film prepared at 100°C. The composition of TiO₂ film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The film showed very good chemical and optical properties while increasing the substrate deposition temperature. The UV–Vis spectroscopy analysis revealed that TiO₂ films exhibited excellent optical transmittance, more than 91% observed in the visible region.     

Optimization of chemical and electrochemical parameters for the preparation of n-type Bi2Te2.7Se0.3 thin films by electrodeposition

A 2^3–1 fractional factorial design comprising four runs and three centre points was applied in order to optimize the electrodeposition process to find a compound with the best stoichiometry leading to a Bi₂Te_2.7Se_0.3 thin film suitable for thermoelectric applications. The key factors considered were the deposition potential, the percentage of bismuth and the percentage of selenium in the solution. The Bi^III, Se^IV, Te^IV electrolyte mixtures in 1 M HNO₃ (pH 0), allowed deposition of ternary alloys to be achieved at room temperature on stainless steel substrates. The deposition mechanism was investigated by linear voltammetry. The films were characterized by micropobe analysis, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The XRD patterns of the film show that the as-deposited are polycrystalline and isostructural to Bi₂Te₃. The SEM study shows that the film is covered by crystallites while the AFM image reveals a low level of roughness.     

Electrodeposition of ZnSe

The conditions of the electrodeposition of a thin film of polycrystalline ZnSe phase on copper substrate from aqueous baths were studied. The electrochemical behavior of Zn²⁺ and H₂SeO₃ species was investigated using cyclic voltammetry. Thin films were deposited potentiostatically on copper substrate and the influence of deposition parameters such as deposition potential, H₂SeO₃ and ZnSO₄ concentration, and temperature of bath on the crystallinity and on the chemical composition of the film is discussed. The ZnSe layers were characterized by X-ray diffraction, X-ray energy dispersive spectroscopy and scanning electron microscopy.     

Electrolytic in-process dressing grinding performance of a multi-layer brazed coarse-grained diamond wheel using an electrolyte containing carbon microspheres

An electrolyte containing carbon microspheres (CMSs) was prepared for electrolytic dressing of a multi-layer brazed coarse-grained diamond wheel. And the influence of CMSs on the electrolytic in-process dressing grinding performance of Si₃N₄ ceramics with the brazed wheel was investigated. The results indicate that the CMSs can increase the electrolytic capacity of the electrolyte, which increases the thickness of the oxide film formed on the brazed wheel surface, and the worn diamond grit can easily fall off from the bonding matrix. In addition, the CMSs were adsorbed and distributed on the film, which effectively improves its densification and adhesion strength. This thicker and denser oxide film can improve the polishing effect of the brazed wheel. Thus, a better machined surface quality and less subsurface damage of the Si₃N₄ ceramics can be obtained by the multi-layer brazed coarse-grained diamond wheel with electrolyte containing CMSs.     

Growth of nanolaminate structure of tetragonal zirconia by pulsed laser deposition

Alumina/zirconia (Al₂O₃/ZrO₂) multilayer thin films were deposited on Si (100) substrates at an optimized oxygen partial pressure of 3 Pa at room temperature by pulsed laser deposition. The Al₂O₃/ZrO₂ multilayers of 10:10, 5:10, 5:5, and 4:4 nm with 40 bilayers were deposited alternately in order to stabilize a high-temperature phase of zirconia at room temperature. All these films were characterized by X-ray diffraction (XRD), cross-sectional transmission electron microscopy (XTEM), and atomic force microscopy. The XRD studies of all the multilayer films showed only a tetragonal structure of zirconia and amorphous alumina. The high-temperature XRD studies of a typical 5:5-nm film indicated the formation of tetragonal zirconia at room temperature and high thermal stability. It was found that the critical layer thickness of zirconia is ≤10 nm, below which tetragonal zirconia is formed at room temperature. The XTEM studies on the as-deposited (Al₂O₃/ZrO₂) 5:10-nm multilayer film showed distinct formation of multilayers with sharp interface and consists of mainly tetragonal phase and amorphous alumina, whereas the annealed film (5:10 nm) showed the inter-diffusion of layers at the interface.     

Particle size separation by alternating electrophoretic deposition

This paper describes a study of the size distribution of the particles deposited under different frequencies by alternating electrophoretic deposition. A low concentration suspension of SnO₂ particles was prepared in acetone and particles of SnO₂ were deposited on electrodes by the low frequency alternating electrophoretic deposition method. Scanning electron microscopy (SEM) showed that increasing the frequency from 0 to 1000 Hz reduces the average size of the SnO₂ particles deposited. Particle size distributions obtained from the SEM images show the sizing capability of the alternating electrophoretic deposition method.     

Structure and stability analyses of collagen hydrolysate coacervates triggered by ethanol in aqueous solution

The coacervation of collagen hydrolysate (CH) in aqueous solution was triggered by ethanol as poor solvent which has a significant effect on the aggregation and rearrangement of CH macromolecules. In this work, the static coacervation was performed to investigate the influences on coacervates morphology. CH concentration and ethanol temperature had significant influences on coacervates morphology. Treatment for the CH solution of high concentration by lower temperature ethanol (<25°C) tended to form the microspheres morphology. High temperature ethanol was not conducive to CH coacervation, while enhanced the CH solubilization in water-ethanol. By directly mixing CH solution and ethanol under agitation, dispersed nanospheres could be successfully obtained in suspension. The turbidity and absorbance tests were carried out to further study the CH coacervation behaviors. The stability of milky suspension induced by ethanol was evaluated by a self-built light transmittance measurement. The result showed that the absorbance and turbidity of CH suspension increased with increasing the V_EtOH ratio and CH concentration. The milky suspension with high V_EtOH would turn clear gradually due to the CH solubilization in water–alcohol. The maximum absorbance presented at pH around 7 where the charges of CH molecules were negative. The coacervation behaviors of CH were very different from that of collagen and gelatin, owing to its lower molecular weight.