Crystallization Kinetics and Morphology Control of Formamidinium–Cesium Mixed‐Cation Lead Mixed‐Halide Perovskite via Tunability of the Colloidal Precursor Solution

The meteoric rise of the field of perovskite solar cells has been fueled by the ease with which a wide range of high‐quality materials can be fabricated via simple solution processing methods. However, to date, little effort has been devoted to understanding the precursor solutions, and the role of additives such as hydrohalic acids upon film crystallization and final optoelectronic quality. Here, a direct link between the colloids concentration present in the [HC(NH₂)₂]_0.83Cs_0.17Pb(Br_0.2I_0.8)₃ precursor solution and the nucleation and growth stages of the thin film formation is established. Using dynamic light scattering analysis, the dissolution of colloids over a time span triggered by the addition of hydrohalic acids is monitored. These colloids appear to provide nucleation sites for the perovskite crystallization, which critically impacts morphology, crystal quality, and optoelectronic properties. Via 2D X‐ray diffraction, highly ordered and textured crystals for films prepared from solutions with lower colloidal concentrations are observed. This increase in material quality allows for a reduction in microstrain along with a twofold increase in charge‐carrier mobilities leading to values exceeding 20 cm² V^?1 s^?1. Using a solution with an optimized colloidal concentration, devices that reach current–voltage measured power conversion efficiency of 18.8% and stabilized efficiency of 17.9% are fabricated.     

碟状胶体：软物质的新兴前沿

回顾了微纳米碟状胶体的研究发展近况,侧重于合成、自组装和它们在软凝聚态物质及材料科学中的角色.首先讨论了各种合成碟状胶体的方法, 包括选择性表面活性剂吸附下的纳米晶体生长、受控沉淀、剥离层状结构化合物、液晶乳液形状变化等等.介绍了这些碟状胶体颗粒在液晶相的形成和悬浮液流变性质等方向的研究应用.特别要提到的是碟状颗粒-聚合物纳米复合材料,如尼龙黏土混合材料、α-ZrP-环氧树脂等在先进功能材料工程中的广泛应用,以及研究人体红细胞的流动性质和形变性质对医疗研究的重大意义.     

Silver-doped biphasic calcium phosphate/alginate microclusters with antibacterial property and controlled doxorubicin delivery

Biphasic calcium phosphate (BCP) based materials possessed with both excellent biocompatibility and antibacterial activity show potential advantages for biomedical applications. Here, the silver-doped BCP/Alginate (_AgBA) microclusters were first fabricated using the double-emulsions method. First, BCP nanoparticles were incorporated into the alginate network to form BCP/Alginate microclusters via the emulsion process. Then, silver nanoparticles (AgNPs) were in situ involved in BCP/Alginate networks to obtain the final _AgBA microclusters. Transmission electron microscopy and scanning electron microscopy confirmed that BCP nanoparticles and AgNPs were uniformly distributed in _AgBA microclusters. The morphology of _AgBA microclusters could be regulated by adjusting emulsion power, and microclusters using the medium powder (500 W) showed a regular spherical shape. Furthermore, CCK-8 analysis identified that _AgBA microclusters were cytocompatible culturing with human bone marrow-derived mesenchymal stem cells. Qualitative antibacterial tests exhibited the excellent inhibition effects of _AgBA microclusters against Staphylococcus aureus (Gram-positive) and Escherichia coli. (Gram-negative). Lastly, the doxorubicin (DOX)-loaded _AgBA microclusters presented adjustable loading efficiency of DOX and controllable release profiles. The cumulative release could reach 73.3% after 72 h in PBS. The above results raised a new route for antibacterial microclusters development for biomedical applications.     

Effect of Steric Structure on the Mechanism of Antioxidant Activity of Alkyl Gallates in Soybean Oil Triacylglycerols—A Kinetic Approach

From an interfacial phenomena standpoint, the effect of the alkyl chain length is evaluated on the mechanism of antioxidant activity of gallic acid ester derivatives (methyl, propyl, octyl, dodecyl, and stearyl gallates) in bulk phase oil. A combinational kinetic model is used to estimate the oxidation kinetic parameters, such as induction period, the maximum concentration of lipid hydroperoxides, and critical reverse micelle concentration. These kinetic parameters are estimated much better with the combinational model compared to the tangent method. The nonlinear behavior is observed for inhibitory activities of homologous series of antioxidants in soybean triacylglycerols. In terms of different kinetics parameters, including antioxidant effectiveness and activity, methyl gallate has the highest inhibitory effect during lipid peroxidation. Gallic acid and alkyl gallates are able to protect bulk oils against peroxidation (induction period > 336 h) in terms of the extent of their participation in the main reaction of chain termination and pro-oxidative side reactions of chain initiation, and anti-oxidative side reactions of chain propagation. Practical Applications: This work explains the effect of the esterification in the inhibitory activity of alkyl gallates, mechanism action of alkyl gallates in bulk oil systems, antiradical potency as a function of the interfacial phenomena, and free radical chain mechanism, the impact of antioxidant activity on critical reverse micelle concentration of hydroperoxides. Moreover, in this study, it is confirmed that the combinational kinetic model can be employed as a reliable method for determining the oxidation kinetic parameters.     

Hybrid nanocoatings in the display industry

Abstract— In the display industry, there is an increasing use of polymeric coatings comprising inorganic nanoparticles. These particles endow the coatings optical, electrical, or mechanical properties not attainable with organic materials, while the use of an organic binder allows easy processing via, e.g., wet deposition and UV or thermal crosslinking. Nanoparticles are relatively new materials and seem to offer numerous opportunities for new coatings for the display industry. Examples of this are silica nanoparticles in anti‐reflection coatings, indium‐tin‐oxide particles in antistatic coatings, and metallic carbon nanotubes in conductive coatings. Yet the physical interactions that determine the dispersion of nanoparticles in the wet formulation and the resulting morphology in the dry coating can be traced back to classical colloid science. In this paper, we focus on some of these principles and their application to nanoparticles dispersed in organic solvents. We illustrate these principles with several examples of anti‐reflection coatings, anti‐static coatings, and hardcoats currently in use in the industry.     

直接电镀用胶体钯催化剂的研制及性能

ABS塑料直接电镀过程省略了化学镀，是塑料电镀史上的重大突破。只有制备出高分散性、粒度小的胶体催化剂，才可以成功实施直接电镀。采用液相还原法制备了几种不同分散性的催化剂，并采用紫外．可见吸收光谱（UV-VIS）、纳米粒度分析仪和立体显微镜来表征不同分散性的胶体钯溶液。分散性好的胶体钯溶液的紫外．可见吸收峰变宽，经过活化可以进行直接电镀。香草醛加入到胶体钯溶液中可以提高分散性和减小胶体粒度。     

Synthesis and properties of metal poly(butyl acrylate)

Butyl acrylate colloids were obtained by codeposition at 77 K of the monomer with several metals such as Pd, Au, Ag, Cu, Zn, Cd, Ga, In, Ge, Sn, Sb, and Bi. The colloids were polymerized with different amounts of an initiator (AIBN) at 65°C for 0.5 h and a wide range of viscosity‐average molecular weights (M _v, 10⁴–10⁵ g/mol) were obtained depending upon the metal used. The metal colloid concentration and stability are reported. The thermal stability and metal composition are also described. The polymers are stable even at 400°C, with Ga–poly(butyl acrylate) being the most stable at 407°C. The metal content ranged between 0.10 and 1.32% w/w for the highest MW fraction and between 0.11 and 1.09% w/w for the lowest MW fraction. Polymers with several colors were obtained depending on the metal used. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 547–550, 1999     

In situ coagulation of yttria-stabilized zirconia ceramic with enhancement of green body via polyvinyl pyrrolidone crosslink

In situ coagulation for yttria-stabilized zirconia (YSZ) suspension via polyvinyl pyrrolidone (PVP) crosslink is reported. PVP is used to prepare sterically stabilized YSZ suspension. Influence of PVP on the dispersion of YSZ suspension was investigated. It indicates that well disperse YSZ suspension with 0.3 wt % PVP can be prepared. Dimethyl sulfate (DMS) was added at 40 °C to coagulate the suspension after degassing. Influence of DMS content and coagulation temperature on coagulation process and properties of green bodies were investigated. It indicates that sufficiently high viscosity to coagulate the suspension is achieved with the addition of 1 vol % DMS at 60~80 °C. The coagulation mechanism is proposed that the YSZ suspension is destabilized by the self-crosslink of PVP. Coagulated samples with the highest wet compressive strength of 6.34 MPa could be demolded without deformation by treating 50 vol % YSZ suspension at 60 °C. Dense YSZ ceramics with relative density above 99.1% and flexural strength of 920 ± 90 MPa had been prepared by this method sintered at 1450 °C for 3 h. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48889.     

Characterization of the isolated wetting crude oil components with infrared spectroscopy

To improve the understanding of wettability, especially the influence of different crude oil colloids, wetting experiments on quartz sand and kaolin were performed with an asphaltene rich oil. A two-step procedure was developed to investigate the wetting behavior. In the first step, those crude oil components were extracted, which preferentially wet solid surfaces. The extracted crude oil components were characterized in a second step. The composition of the fractions extracted with different solvents are different. The acetone fractions extracted from quartz sand are rich in compounds containing nitrogen, whereas the compounds containing sulphur predominate in the chloroform fraction extracted from quartz sand. IR spectroscopy of the extracted fractions shows that carbonyl compounds are abundant in the methanol/chloroform and acetone/chloroform fractions extracted from quartz sand. The chloroform fraction is poor in carbonyl group-containing compounds. In agreement with elemental analysis, a strong signal for C–N groups in the IR spectra is found for acetone/chloroform and methanol/chloroform fractions, extracted from the quartz sand system. On the other hand, a significant, strong IR-peak representing S=O containing components is observed in the acetone and acetone/chloroform fractions, extracted from quartz sand.     

Poly(N‐isopropylacrylamide)‐grafted silica as a support of platinum colloids: Preparation method,characterization, and catalytic properties in hydrogenation

We investigated the composition, properties, and utility of a novel hybrid material of poly(N‐isopropylacrylamide)‐grafted silica. The modified silica was prepared in two steps: (1) grafting silane layers of active precursors, such as initiator, transfer agent or comonomer onto the silica surface by solution deposition and (2) radical polymerization of N‐isopropylacrylamide (NIPAAm) on the grafted silane layers. Thermogravimetric analysis (TGA), elemental analysis (EA), FTIR spectroscopy, and TEM were used to characterize the layer composition, structure, and chemistry, respectively. Well‐dispersed platinum colloids have been prepared on the PNIPAAm‐grafted silica via the reduction of PtCl by ethanol. The immobilized Pt colloids were found to be active and stable heterogeneous catalysts for the hydrogenation of ally alcohol in ethanol. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2678–2684, 2000