Dispersions

分散体
  • 文章类型: Journal Article
    纳米纤维素,来自可再生生物质来源的纳米级衍生物,在水中具有显著的胶体特性,机械强度,和生物相容性。它成为水中各种纳米材料的有前途的生物基分散剂。这篇小型评论探讨了纤维素纳米材料(纳米晶体或纳米纤维)与水之间的相互作用,阐明这可能如何使他们成为一种环保分散剂的潜力。我们探索了从自上而下的过程中衍生的纳米纤维素的潜力,纳米晶体,和分散碳纳米材料的纳米纤维,半导体氧化物纳米粒子,和其他纳米材料在水中。我们还强调了其优于传统方法的优势,不仅有效地分散了这些纳米材料,而且有可能消除对进一步化学处理或支持稳定剂的需求。这不仅保留了纳米材料在水分散体中的特殊性能,但甚至可能导致新的混合功能的出现。总的来说,这篇小型评论强调了纳米纤维素作为各种纳米材料的绿色分散剂的非凡多功能性,激发进一步的研究,将其潜力扩展到其他纳米材料和应用。
    Nanocellulose, a nanoscale derivative from renewable biomass sources, possesses remarkable colloidal properties in water, mechanical strength, and biocompatibility. It emerges as a promising bio-based dispersing agent for various nanomaterials in water. This mini-review explores the interaction between cellulose nanomaterials (nanocrystals or nanofibers) and water, elucidating how this may enable their potential as an eco-friendly dispersing agent. We explore the potential of nanocellulose derived from top-down processes, nanocrystals, and nanofibers for dispersing carbon nanomaterials, semiconducting oxide nanoparticles, and other nanomaterials in water. We also highlight its advantages over traditional methods by not only effectively dispersing those nanomaterials but also potentially eliminating the need for further chemical treatments or supporting stabilizers. This not only preserves the exceptional properties of nanomaterials in aqueous dispersion, but may even lead to the emergence of novel hybrid functionalities. Overall, this mini-review underscores the remarkable versatility of nanocellulose as a green dispersing agent for a variety of nanomaterials, inspiring further research to expand its potential to other nanomaterials and applications.
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  • 文章类型: Journal Article
    乳液是复杂的。分散两个不混溶的相,从而扩展了一个接口,需要努力才能实现,并且所得的分散体在热力学上是不稳定的,推动系统走向合并。此外,身体不稳定,包括乳化,由于存在不同密度的分散液滴而形成连续相。乳液允许油的配方,可以作为载体来溶解亲水和亲脂分子,并且可以根据所需的流变曲线进行调整,包括“凝胶样”行为和剪切稀化。乳液的有用性可以通过赋予刺激响应或“智能”行为通过包含刺激响应乳化剂进一步扩大,聚合物或表面活性剂。这使得操作像凝胶化,breaking,或聚合,通过外部触发,如pH,温度,或盐浓度变化。这个平台产生药物的功能材料,化妆品,采油,和胶体工程,结合聪明的行为和乳液的内在益处。然而,增加的功能带来更大的复杂性。这篇综述的重点是使用刺激响应聚合物来生成智能乳液,由于聚合物对这种应用的巨大适应性以及它们作为空间稳定剂的功效。根据用于向读者提供本领域进展的概述的触发器描述了刺激响应性乳剂。本文受版权保护。保留所有权利。
    Emulsions are complex. Dispersing two immiscible phases, thus expanding an interface, requires effort to achieve and the resultant dispersion is thermodynamically unstable, driving the system toward coalescence. Furthermore, physical instabilities, including creaming, arise due to presence of dispersed droplets of different densities to a continuous phase. Emulsions allow the formulation of oils, can act as vehicles to solubilize both hydrophilic and lipophilic molecules, and can be tailored to desirable rheological profiles, including \"gel-like\" behavior and shear thinning. The usefulness of emulsions can be further expanded by imparting stimuli-responsive or \"smart\" behaviors by inclusion of a stimuli-responsive emulsifier, polymer or surfactant. This enables manipulation like gelation, breaking, or aggregation, by external triggers such as pH, temperature, or salt concentration changes. This platform generates functional materials for pharmaceuticals, cosmetics, oil recovery, and colloid engineering, combining both smart behaviors and intrinsic benefit of emulsions. However, with increased functionality comes greater complexity. This review focuses on the use of stimuli-responsive polymers for the generation of smart emulsions, motivated by the great adaptability of polymers for this application and their efficacy as steric stabilizers. Stimuli-responsive emulsions are described according to the trigger used to provide the reader with an overview of progress in this field.
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  • 文章类型: Journal Article
    剥离的MoS2的应用受到其惰性表面和不良界面的限制。我们已经通过与NaBH4反应激活了剥离的2H-MoS2的表面,形成了n掺杂的材料,如负ζ电位值ζ=-25mV和20nm(0.05eV)的红移所示其光致发光光谱。新材料的光谱特性与原始2H-MoS2一致(通过HR-TEM测定,XPS,pXRD,漂移,TGA,和拉曼光谱)。重要的是,与2H-MoS2不同,它容易分散在H2O中。对各种溶剂的分散性进行了研究,并且可以与相应溶剂的相对介电常数直接相关。带电的2H-MoS2容易与有机碘化物反应以提供官能化的2H-MoS2。我们的方法提供了半导体2H-MoS2的水分散体,没有添加剂或化学官能团,并允许2H-MoS2的受控和容易的功能化,为半导体MoS2应用开辟了多种新途径。
    The applications of exfoliated MoS2 are limited by its inert surface and poor interface. We have activated the surface of exfoliated 2H-MoS2 by reacting it with NaBH4 , forming an n-doped material as demonstrated by a negative zeta-potential value ζ=-25 mV and a 20 nm (0.05 eV) red-shift in its photoluminescence spectrum. The novel material\'s spectral properties were consistent with pristine 2H-MoS2 (as determined by HR-TEM, XPS, pXRD, DRIFT, TGA, and Raman spectroscopy). Importantly, it was readily dispersed in H2 O unlike 2H-MoS2 . Its dispersibility properties were explored for a variety of solvents and could be directly correlated with the relative permittivity of the respective solvents. The charged 2H-MoS2 reacted readily with an organo-iodide to deliver functionalized 2H-MoS2 . Our approach delivers aqueous dispersions of semiconducting 2H-MoS2 , without additives or chemical functionalities, and allows for controlled and facile functionalization of 2H-MoS2 opening multiple new avenues of semi-conducting MoS2 application.
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  • 文章类型: Journal Article
    根据稳定和去稳定分子内相互作用的相对贡献,分析了描述具有异常长的单个C-C键的分子的理论挑战。Diamondoid二聚体是稳定的,尽管C-C键的存在长达1.7埃长,以及由于分子内非共价相互作用(伦敦分散体)而稳定的其他大分子进行了讨论。高度拥挤的分子意想不到的稳定性,如金刚石酮二聚体和叔丁基取代的六苯基乙胺,呼吁重新考虑传统上认为会破坏分子稳定性的“空间效应”。或者,“空间吸引”有助于理解空间过载分子中的键合,其结构和能量分析需要对非共价相互作用进行适当的理论描述。
    Theoretical challenges in describing molecules with anomalously long single C-C bonds are analyzed in terms of the relative contributions of stabilizing and destabilizing intramolecular interactions. Diamondoid dimers that are stable despite the presence of C-C bonds up to 1.7 Å long, as well as other bulky molecules stabilized due to intramolecular noncovalent interactions (London dispersions) are discussed. The unexpected stability of highly crowded molecules, such as diamondoid dimers and tert-butyl-substituted hexaphenylethanes, calls for reconsideration of the \"steric effect\" traditionally thought to destabilize the molecule. Alternatively, \"steric attraction\" helps to understand bonding in sterically overloaded molecules, whose structural and energetic analysis requires a proper theoretical description of noncovalent interactions.
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  • 文章类型: Journal Article
    迄今为止只有少数研究集中在通过常规烧结方法向SS316L合金中添加银。不幸的是,含银抗微生物SS的冶金过程由于银在铁中的溶解度极低以及其在晶界处沉淀的趋势而受到极大限制,导致抗菌相的不均匀分布和抗菌性能的损失。在这项工作中,我们提出了一种通过功能化聚乙烯亚胺-戊二醛共聚物(PEI-co-GA/Ag催化剂)复合材料制造抗菌不锈钢316L的新方法。PEI是一种高度支化的阳离子聚合物,这使得它在基材表面表现出非常好的粘附性。与传统银镜反应的效果不同,功能聚合物的引入可以有效提高Ag颗粒在316LSS表面的附着力和分布。从SEM图像可以看出,烧结后大量银颗粒保留并很好地分散在316LSS中。PEI-co-GA/Ag316LSS具有优异的抗菌性能,不会释放游离银离子影响周围环境。此外,还提出了功能复合材料对附着力增强影响的可能机理。大量的氢键和范德华力的形成,以及316LSS表面的负ζ电位,可以有效地使Cu层与316LSS表面之间形成紧密的引力。这些结果满足了我们对在医疗设备的接触表面上设计被动抗菌性能的期望。
    Only a few studies have so far focused on the addition of silver to SS316L alloys by conventional sintering methods. Unfortunately, the metallurgical process of silver-containing antimicrobial SS is greatly limited due to the extremely low solubility of silver in iron and its tendency to precipitate at the grain boundaries, resulting in an inhomogeneous distribution of the antimicrobial phase and loss of antimicrobial properties. In this work, we present a novel approach to fabricate antibacterial stainless steel 316L by functional polyethyleneimine-glutaraldehyde copolymer (PEI-co-GA/Ag catalyst) composites. PEI is a highly branched cationic polymer, which makes it exhibit very good adhesion on the surface of the substrate. Unlike the effect of the conventional silver mirror reaction, the introduction of functional polymers can effectively improve the adhesion and distribution of Ag particles on the surface of 316LSS. It can be seen from the SEM images that a large number of silver particles are retained and well dispersed in 316LSS after sintering. PEI-co-GA/Ag 316LSS exhibits excellent antimicrobial properties and does not release free silver ions to affect the surrounding environment. Furthermore, the probable mechanism for the influence of the functional composites on the enhancement of adhesion is also proposed. The formation of a large number of hydrogen bonds and van der Waals forces, as well as the negative zeta potential of the 316LSS surface, can effectively enable the formation of a tight attraction between the Cu layer and the surface of 316LSS. These results meet our expectations of designing passive antimicrobial properties on the contact surface of medical devices.
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  • 文章类型: Journal Article
    目的:水性涂料作为有机溶剂型体系的可持续替代品正在迅速发展。通常将无机胶体添加到水性聚合物分散体中以增强水性涂料的性能。然而,这些双峰分散体具有许多可导致不稳定的胶体和不期望的相分离的界面。单个胶体之间的共价键,在聚合物-无机核-电晕上胶体组件上,可以减少或抑制涂层干燥过程中的不稳定性和相分离,提高其机械和光学性能。
    方法:使用具有核心-电晕草莓构型的水性聚合物-二氧化硅suproolloids来精确控制涂层内的二氧化硅纳米颗粒分布。对聚合物和二氧化硅颗粒之间的相互作用进行微调,以获得共价结合或物理吸附的suproolloid。通过在室温下干燥半胶体分散体制备涂层,它们的形态和力学性能相互联系。
    结果:共价结合的suproolloids提供了具有均匀3D渗滤二氧化硅纳米网络的透明涂层。仅具有物理吸附作用的suporloids,导致在界面处具有分层二氧化硅层的涂层。排列良好的二氧化硅纳米网大大提高了涂层的储能模量和耐水性。这些suprolloidal分散体为制备具有增强的机械性能和其他功能的水性涂料提供了新的范例,像结构颜色。
    OBJECTIVE: Water-borne coatings are rapidly expanding as sustainable alternatives to organic solvent-borne systems. Inorganic colloids are often added to aqueous polymer dispersions to enhance the performance of water-borne coatings. However, these bimodal dispersions have many interfaces which can result in unstable colloids and undesirable phase separation. The covalent bonding between individual colloids, on a polymer-inorganic core-corona supracolloidal assembly, could reduce or suppress instability and phase separation during drying of coatings, advancing its mechanical and optical properties.
    METHODS: Aqueous polymer-silica supracolloids with a core-corona strawberry configuration were used to precisely control the silica nanoparticles distribution within the coating. The interaction between polymer and silica particles was fine-tuned to obtain covalently bound or physically adsorbed supracolloids. Coatings were prepared by drying the supracolloidal dispersions at room temperature, and their morphology and mechanical properties were interconnected.
    RESULTS: Covalently bound supracolloids provided transparent coatings with a homogeneous 3D percolating silica nanonetwork. Supracolloids having physical adsorption only, resulted in coatings with a stratified silica layer at interfaces. The well-arranged silica nanonetworks strongly improve the storage moduli and water resistance of the coatings. These supracolloidal dispersions offer a new paradigm for preparing water-borne coatings with enhanced mechanical properties and other functionalities, like structural color.
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  • 文章类型: Journal Article
    对导热纳米流体日益增长的兴趣需要高度灵敏的方法来分析热特性。热透镜光谱法(TLS),尽管它比经典方法有优势,没有测量和解释分散系统结果的通用方法。在本文中,对于各种浓度和大小的二氧化硅在水中的纳米流体,瞬态和稳态热透镜测量参数的选择是合理的,并证实了对热扩散率测量结果的解释。考虑了在分散系统的稳态下通过TLS测量热扩散率的特征。使用这种方法,可以高精度地检测和区分热效应。对于氧化硅的分散体,随着浓度的增加,热扩散率通过最小阈值。通过选择粒度和浓度,氧化硅分散体可用作冷却剂或用作除热液体。
    The growing interest in heat-conducting nanofluids requires highly sensitive methods for analyzing the thermal properties. Thermal lens spectrometry (TLS), despite its advantages over classical methods, does not have a general approach for measuring and interpreting results for dispersed systems. In this paper, for nanofluids of silicon oxide in water in a wide range of concentrations and sizes, the selection of measurement parameters for transient and steady-state thermal lensing is justified, and the interpretation of the results of thermal diffusivity measurements is substantiated. The features of the measurements of thermal diffusivity by TLS under stationary states for dispersed systems are considered. Using this approach, it is possible to detect and distinguish thermal effects with high accuracy. For dispersions of silicon oxide, with increasing concentrations, the thermal diffusivity passes through a minimum threshold. Silicon oxide dispersions can be used both as coolants or as heat-removing liquids by selecting the particle size and concentration.
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  • 文章类型: Journal Article
    动态结构因子(Q,E),QandEare的动量和能量转移,分别,已使用非弹性X射线散射测量了液体Eu8Ga16Ge30。液体中纵向声模的激发能量被放大到具有有效质量的液体Ba8Ga16Sn30中的激发能量。该结果意味着两种液体中的局部结构是相似的。I型包合物Eu8Ga16Ge30的纵向声激发能量比在液体中分散更快,这表明原子间的力在熔化时减弱。在液体Eu8Ga16Ge30和液体Ba8Ga16Sn30中均观察到较低的能量激发。与通过基于DFT的计算获得的晶体包合物Eu8Ga16Ge30中的纵向声子色散相比,发现液体中的较低能量接近光模能量。结果表明,较低的能量模式来自Eu和(Ga,Ge)原子。
    The dynamic structure factorS(Q,E), whereQandEare momentum and energy transfer, respectively, has been measured for liquid Eu8Ga16Ge30(EGG), using inelastic x-ray scattering. The excitation energy of the longitudinal acoustic mode in the liquid was scaled to that in liquid Ba8Ga16Sn30(BGS) with the effective mass. This result means that the local structure in both liquids are similar. The longitudinal acoustic excitation energy of type-I clathrate compound EGG disperses faster than that in the liquid, suggesting that the interatomic force is weakened on melting. The lower energy excitation was observed in both liquid EGG and liquid BGS. In comparison with the longitudinal phonon dispersion in crystalline clathrate compound EGG obtained by density functional theory-based calculations, the lower energy in the liquid was found to be near the optical mode energy. The result indicates that the lower energy mode arises from the relative motion between Eu and (Ga, Ge) atoms.
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  • 文章类型: Journal Article
    解决耦合到连续流体的分散相的动力学的种群平衡方程(PBE)是昂贵的。尽管如此,可以通过用矩来表示不断发展的粒子密度函数来降低成本。特别是,基于正交的矩量方法(QBMM)用正交规则反转这些矩,接近所需的统计数据。QBMM已被证明可以准确地模拟喷雾和烟灰,并具有相对紧凑的力矩集。然而,明显的非高斯过程,如气泡动力学导致数值不稳定性时,相应地延长他们的力矩集。我们通过训练递归神经网络(RNN)来解决这个问题,该神经网络调整QBMM正交以更高的精度评估非闭合矩。所提出的方法在响应于时间波动的压力场而振荡的简单气泡模型上进行了测试。与传统的QBMM相比,该方法将模型形式误差降低了10倍。由于它不扩展基线矩集,因此它在数值上稳定且计算上高效。还评估了其他正交点,根据额外的RNN进行最佳放置和加权。这些点进一步以低成本减小误差,因为时刻集合再次不变。本文是“动态系统中的数据驱动预测”主题的一部分。
    Solving the population balance equation (PBE) for the dynamics of a dispersed phase coupled to a continuous fluid is expensive. Still, one can reduce the cost by representing the evolving particle density function in terms of its moments. In particular, quadrature-based moment methods (QBMMs) invert these moments with a quadrature rule, approximating the required statistics. QBMMs have been shown to accurately model sprays and soot with a relatively compact set of moments. However, significantly non-Gaussian processes such as bubble dynamics lead to numerical instabilities when extending their moment sets accordingly. We solve this problem by training a recurrent neural network (RNN) that adjusts the QBMM quadrature to evaluate unclosed moments with higher accuracy. The proposed method is tested on a simple model of bubbles oscillating in response to a temporally fluctuating pressure field. The approach decreases model-form error by a factor of 10 when compared with traditional QBMMs. It is both numerically stable and computationally efficient since it does not expand the baseline moment set. Additional quadrature points are also assessed, optimally placed and weighted according to an additional RNN. These points further decrease the error at low cost since the moment set is again unchanged. This article is part of the theme issue \'Data-driven prediction in dynamical systems\'.
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  • 文章类型: Journal Article
    虾青素(AXT)广泛应用于食品中,药物,和化妆品领域,但是它的应用受到其固有特性的极大限制。在这里,通过乳液溶剂蒸发和喷雾干燥方法,已经进行了一种新型的包封系统来制造AXT负载的微胶囊。研究了聚乳酸(PLA)浓度对AXT负载分散体和所得微胶囊特性的影响。结果表明,分散体和微胶囊的尺寸和ζ电位随着PLA含量的增加而增加(9.8至24.6wt%)。微胶囊的包封效率(EE)随着PLA浓度增加至21.4wt%而增加。水分含量值,流动性,随着PLA含量的增加(9.8至24.6wt%),所得微胶囊的堆积密度降低。此外,细胞培养实验表明,所得微胶囊无细胞毒性,具有良好的抗氧化活性。这项工作为制造富含AXT的微胶囊提供了新的策略,并扩大了它们在营养产品中的应用。实际应用:这项工作通过乳液溶剂蒸发和喷雾干燥方法制造了用于AXT的新型封装系统。所得AXT微胶囊具有良好的物理稳定性,可拓展AXT的潜在应用。
    Astaxanthin (AXT) is widely used in the food, drug, and cosmetics fields, but its applications are extremely limited by its intrinsic properties. Herein, a novel encapsulation system had been performed to fabricate AXT-loaded microcapsules through emulsion solvent evaporation and spray-dried methodologies. The influence of polylactic acid (PLA) concentrations on the characteristics of AXT-loaded dispersions and resultant microcapsules were investigated. The results showed that the sizes and zeta potentials of dispersions and microcapsules increased with increasing PLA content (9.8 to 24.6 wt%). The encapsulation efficiency (EE) of the microcapsules increased with increasing PLA concentration up to 21.4 wt%. The moisture content values, flowability, and bulk density of the obtained microcapsules decreased with increasing PLA content (9.8 to 24.6 wt%). Furthermore, the cell culture experiment indicated that the obtained microcapsules had no cytotoxicity and possessed excellent antioxidant activity. This work provides a new strategy for fabricating AXT-enriched microcapsules and expands their application in nutritional products. PRACTICAL APPLICATION: This work fabricated a novel encapsulation system for AXT through emulsion solvent evaporation and spray drying methodologies. The obtained AXT-loaded microcapsules possessed great physical stability and could expand potential applications of AXT.
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