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991.
The booming development of organometal halide perovskites in recent years has prompted the exploration of morphology‐control strategies to improve their performance in photovoltaic, photonic, and optoelectronic applications. However, the preparation of organometal halide perovskites with high hierarchical architecture is still highly challenging and a general morphology‐control method for various organometal halide perovskites has not been achieved. A mild and scalable method to prepare organometal halide perovskites in inverse opal morphology is presented that uses a polystyrene‐based artificial opal as hard template. Our method is flexible and compatible with different halides and organic ammonium compositions. Thus, the perovskite inverse opal maintains the advantage of straightforward structure and band gap engineering. Furthermore, optoelectronic investigations reveal that morphology exerted influence on the conducting nature of organometal halide perovskites. 相似文献
992.
Silver‐Assisted Chemical Etching on Silicon with Polyvinylpyrrolidone‐Mediated Formation of Silver Dendrites 下载免费PDF全文
Metal‐assisted chemical etching (MaCE) on silicon (Si)—mediated by polyvinylpyrrolidone (PVP)—is systematically investigated herein. It is found that the morphologies and crystallographic natures of the grown silver (Ag) dendrites can be significantly modulated, with the presence of PVP in the MaCE process leading to the formation of faceted Ag dendrites preferentially along the (111) crystallographic phase, rather than along the (200) phase. Further explorations of the PVP‐mediated effect on Si etching are also revealed. In contrast to the aligned Si nanowires formed by MaCE without PVP addition, only distributed nanopores with sizes of 200 to 400 nm appear on the Si surfaces in the presence of PVP. The origin of surface polishing on Si in the PVP‐mediated MaCE process can be attributed to the distinct transport pathway of holes supplied by the Ag+ ions, where the holes are injected directly into the primary Ag seeds, rather than through Ag dendrites, thus leading to the isotropic etching of the Si surface. 相似文献
993.
Effect of polyethylene glycol on the crystallization and impact properties of polylactide‐based blends 下载免费PDF全文
Polylactide (PLA) was plasticized by polyethylene glycols (PEGs) with five different molecular weights (Mw = 200–20,000 g/mol). The effects of content and molecular weight of PEG on the crystallization and impact properties of PLA were studied by wide‐angle X‐ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy, and V‐notched impact tests, respectively. The results revealed that PEG‐10,000 could significantly improve the crystallization capacity and impact toughness of PLA. When the PEG‐10,000 content ranged from 0 to 20 wt%, the increases in both V‐notched Izod and Charpy impact strengths of PLA/PEG‐10,000 blends were 206.10% and 137.25%, respectively. Meanwhile, the crystallinity of PLA/PEG‐10,000 blends increased from 3.95% to 43.42%. For 10 wt% PEG content, the crystallization and impact properties of PLA/PEG blends mainly depended upon PEG molecular weight. With increasing the Mw of PEG, the crystallinity and impact strength of PLA/PEG blends first decreased and then increased. The introduction of PEG reduced the intermolecular force and enhanced the mobility of PLA chains, thus improving the crystallization capacity and flexibility of PLA. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
994.
Two liquid phases were formed as the addition of a certain amount of biological buffer 3-(N-morpholino)propane sulfonic acid (MOPS) in the aqueous solutions of tetrahydrofuran (THF) or 1,3-dioxolane. To evaluate the feasibility of recovering the cyclic ethers from their aqueous solutions with the aid of MOPS, we determined experimentally the phase diagrams of the ternary systems of {cyclic ether (THF or 1,3-dioxolane) + water + MOPS} at T = 298.15 K under atmospheric pressure. In this study, the solubility data of MOPS in water and in the mixed solvents of water/cyclic ethers were obtained from the results of a series of density measurements, while the (liquid + liquid) and the (solid + liquid + liquid) phase boundaries were determined by visually inspection. Additionally, the tie-line results for (liquid + liquid) equilibrium (LLE) and for (solid + liquid + liquid) equilibrium (SLLE) were measured using an analytical method. The reliability of the experimental LLE tie-line results data was validated by using the Othmer–Tobias correlation. These LLE tie-line values were correlated well with the NRTL model. The phase diagrams obtained from this study reveal that MOPS is a feasible green auxiliary agent to recover the cyclic ethers from their aqueous solutions, especially for 1,3-dioxolane. 相似文献
995.
(Solid + liquid) equilibrium data for indomethacin (IMC) and nicotinamide (NCT) in both methanol (MeOH) and methanol/ethyl acetate (EA) mixture were determined using a static method at T = (298.15 and 313.15) K under atmospheric pressure. The 1:1 (IMC + NCT) co-crystal and IMC·MeOH were found in both systems under conditions investigated. The solubility of the 1:1 (IMC + NCT) co-crystal was correlated using a mathematical model consisting of both solubility product and a complexation process. Solubility of (IMC + NCT) co-crystals as a function of co-former (NCT) concentration was evaluated. It was found that temperature has a significant effect on the formation of methanol solvate in the systems investigated. Solvate formation could be suppressed either by increasing temperature or using solvent mixtures. Additionally, the solvent mixture could level out the solubility differences between IMC and NCT, resulting in larger and more symmetric regions for the (IMC + NCT) co-crystal, which would be helpful to the development of the co-crystallization process for the 1:1 (IMC + NCT) co-crystal. 相似文献
996.
Experimental Investigation on Binary Phase Diagram of the Thermotropic Phase Transitions Compounds (n‐CnH2n+1R3)2ZnCl4 下载免费PDF全文
The thermotropic phase transitions compounds (n‐CnH2n+1R3)2ZnCl4 as well as a series of their binary mixtures were prepared by a solution reflux method from their ethanol solutions. The experimental subsolidus binary phase diagram of [n‐C18H37N(CH3)3]2ZnCl4‐[n‐(C18H37)2N(CH3)2]2ZnCl4 is constructed over the entire composition range by differential scanning calorimetry(DSC) and X‐ray. Experi‐ mental results indicate one stable intermediate phase [n‐C18H37N(CH3)3] [n‐(C18H37)2N(CH3)2]ZnCl4 at WC18C3Zn %=59.75 %, and two invariant three phase equilibria, which shows two eutectoid temperatures: Te1 at 310±1 K for eutectoid point WC18C3Zn %=36.24 %, Te2 at 313±1 K for eutectoid point WC18C3Zn %=80.17 %. These three noticeable solid‐solution ranges are α‐phase at the left, ?‐phase at the right, and ψ‐phase in the middle of the phase diagram. It is (n‐CnH2n+1R3)2ZnCl4 systems as phase change materials that are characterized the phase transition temperatures T in the range of 310 to 340 K, the transition enthalpies ΔH in the range of 38.40 and 168.72 J/g between two polymorphic forms. 相似文献
997.
利用旋转涂膜方法制备了以P3HT:PCBM为有源层的聚合物太阳能电池, 器件结构为ITO/PEDOT:PSS/P3HT:PCBM/Al(氧化铟锡导电玻璃/聚二氧乙基噻吩:聚对苯乙烯磺酸/聚三已基噻酚:富勒烯衍生物/铝),研究了退火温度对聚合物太阳能电池性能的影响. 实验发现: 聚合物薄膜经过120 °C退火10 min处理后, 开路电压(Voc)达到0.64 V, 短路电流密度(Jsc)为10.25 mA·cm-2, 填充因子(FF) 38.1%, 光电转换效率(PCE)达到2.00%. 为了讨论其内在机制, 对不同退火条件下聚合物薄膜进行了各种表征. 从紫外-可见吸收光谱中发现, 退火处理使P3HT在可见光范围内吸收加强且吸收峰展宽, 特别是在560和610 nm处的吸收强度明显增大; X射线衍射(XRD)结果表明, 120 °C退火后P3HT在(100)晶面上的衍射强度是未退火薄膜的2.8倍, 有利于光生载流子的输运; 原子力显微镜(AFM)研究结果表明, 退火显著增大了P3HT与PCBM的相分离程度, 提高了激子解离的几率; 傅里叶变换红外(FTIR)光谱验证了退火并没有引起聚合物材料物性的变化. 相似文献
998.
Martin Faber Anton H. Hofman Katja Loos Gerrit ten Brinke 《Macromolecular rapid communications》2016,37(11):911-919
Linear poly(4‐tert‐butoxystyrene)‐b‐poly(4‐vinylpyridine) (PtBOS‐b‐P4VP) diblock copolymers are synthesized using reversible addition–fragmentation chain transfer polymerization. The self‐assembly of four different PtBOS‐b‐P4VP diblock copolymers is studied using small‐angle X‐ray scattering and transmission electron microscopy and a number of interesting observations are made. A tBOS62‐b‐4VP28 diblock copolymer with a weight fraction P4VP of 0.21 shows a disordered morphology of P4VP spheres with liquid‐like short‐range order despite an estimated value of of the order of 50. Increasing the length of the 4VP block to tBOS62‐b‐4VP199 results in a diblock copolymer with a weight fraction P4VP of 0.66. It forms a remarkably well‐ordered lamellar structure. Likewise, a tBOS146‐b‐4VP120 diblock copolymer with a weight fraction P4VP of 0.33 forms an extremely well‐ordered hexagonal structure of P4VP cylinders. Increasing the P4VP block of this block copolymer to tBOS146‐b‐4VP190 with a weight fraction P4VP of 0.44 results in a bicontinuous gyroid morphology despite the estimated strong segregation of . These results are discussed in terms of the architectural dissimilarity of the two monomers, characterized by the presence of the large side group of PtBOS, and the previously reported value of the interaction parameter, , for this polymer pair.
999.
1000.
Latent heat storage performance of a layered perovskite-type compound, 1-C_(14)H_(29)NH_3)_2ZnCl_4(C_(14)Zn),embedded in a series of silica gel(SG) with pore sizes of d = 15–200 nm is investigated using differential scanning calorimetry(DSC), and powder X-ray diffractions(XRD). C_(14)Zn in the nanopores of silica gel shows size-dependent phase transition temperature, enthalpy change and supercooling. They have a stable transition temperature and heat capacity at each size in a short-term thermal cycling. Similar Xray diffraction patterns are observed for the nano-sized and the bulk C_(14)Zn. The encapsulation of a phase change material in nanopores is a new way of tuning its thermal energy storage properties for a wider range of temperature regulation. 相似文献