二维纳米片用于快速高效膜法气体分离

膜法气体分离作为一类低能耗先进分离技术, 在化工分离中具有广阔的应用前景. 然而商业气体分离膜在实际应用过程中存在选择性和渗透性此消彼长的问题. 以二维纳米片材料为膜构筑基元, 有望突破这一瓶颈. 最具代表性的二维纳米片膜材料当属石墨烯及其衍生物、 二维沸石分子筛、 层状双金属氢氧化物、 二维过渡金属硫化物、 Mxene、 二维共价有机骨架和金属有机骨架材料. 本文对这些二维材料在超薄气体分离膜领域的成果与进展进行介绍, 展现了各类材料在实际分离应用过程中的优势及弊端, 探讨了二维纳米片膜材料在气体分离领域的挑战与发展前景.     

二维材料膜在气体分离领域的最新研究进展（英文）

以石墨烯代表的二维材料已经成为新型高性能膜的纳米构建单元。原子级厚度的纳米片有利于制备超薄膜,极大提升膜的通量;与此同时,可实现在亚纳米级别精度下操纵传输通道实现精确的分子筛分,在气体分离领域有着广阔的前景。本文简要综述了二维材料膜在气体分离领域的最新突破性研究,重点介绍了如何实现亚纳米级别的二维通道,结构完整的二维纳米片的剥离方法及气体传输特性可调节的层间通道,并分析了二维材料膜发展面临的挑战和机遇。     

高储能密度聚酰亚胺/钛酸钡/水滑石复合薄膜的制备与性能

利用零维纳米粒子与二维纳米片在聚合物基体中的协同分散,构筑纳米粒子/二维纳米片/聚酰亚胺(PI)三元复合体系,系统研究了零维-二维组合纳米填料对复合材料介电常数、击穿强度、储能密度以及机械性能的影响.结果表明:采用氟碳表面活性剂插层修饰可以将水滑石剥离为水滑石二维纳米片(HT),在此纳米片溶液中分散钛酸钡纳米粒子(BT),并进行聚酰亚胺的原位聚合.在聚合物溶液形成薄膜的过程中,二维纳米片和纳米粒子的协同作用抑制了各自的团聚,改善了2种纳米填料在聚合物薄膜中的分散状况.在所制备的PI/BT/HT复合薄膜中,HT有利于改善BT在PI基体中的均匀分散,提高了薄膜的击穿强度,进而提升了复合薄膜的储能密度.与仅加入20%BT相比,在聚酰亚胺中同时加入2种填料20%BT和1%HT时,击穿强度达到354.4 kV/mm,储能密度达到2.58 J/cm3,分别提高了12.4%和14.6%.因此,在纳米粒子/聚合物复合材料中增加少量二维纳米片就可以显著改善其性能,这种方法有望在更多纳米复合功能材料领域得到应用.     

sp2碳连接的二维聚合物

二维多孔聚合物具有光学各向异性、高的电子迁移率、可逆的氧化还原等众多特性,因此它们作为关键材料用于气体吸附与分离、燃料电池膜、超级电容器等领域。这类二维多孔聚合物通常可分为二维金属-有机骨架、二维共价有机骨架、石墨化氮化碳、石墨炔和三明治型多孔聚合物纳米片。其中,sp~2杂化碳(C_(sp~2))连接的二维多孔聚合物是新兴的研究领域。与C―N、B―O和C≡C键连接的二维多孔聚合物相比,C_(sp~2)-二维聚合物因其高的电子迁移率和可调的带隙而具有独特的光电性质、高的化学/光稳定性和可调的电化学性质。此外,C_(sp~2)-二维多孔聚合物是制备过渡金属单原子的2D多孔碳材料的重要前驱体之一。总结了C_(sp~2)-二维多孔聚合物的可控合成方法,并讨论了它们在光电器件、气体分离、发光传感和成像、电化学能源存储和光催化等领域的应用情况。     

二维水滑石纳米片对氧化铝/聚酰亚胺复合薄膜耐电晕性能的影响

将二维层状材料水滑石剥离为二维纳米片分散液,向其中加入纳米氧化铝,并进行聚酰亚胺(PI)的原位聚合,构筑PI/水滑石纳米片/氧化铝纳米粒子三元复合薄膜。 结果表明,在PI薄膜中同时加入质量分数为10%氧化铝和2%水滑石纳米片,比仅加入质量分数为10%氧化铝时的耐电晕时间(180 min)提高了12倍,拉伸强度提高了37.8%。 聚合物中同时加入纳米片、纳米粒子两种不同形貌填料,能够同时提升复合材料的耐电晕性能和机械性能。     

Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

以水溶性聚合物为保护剂,采用化学还原法制备了银纳米粒子,分别利用透射电子显微镜、紫外可见光谱、同步光散射光谱等手段对其进行了表征,并探索了制备银纳米粒子的最佳实验条件。通过将银纳米粒子-聚合物溶液进行脱水,得到含有银纳米粒子的固态聚合物膜。将固态聚合物膜重新溶解于水,其水溶液的紫外可见光谱与脱水前的溶液进行了比较,发现两者性质并无明显差异。因此,将银纳米粒子分散固定在聚合物膜中是一种崭新而有效的银纳米粒子制备和存储方法。     

模板法合成纳米结构材料

模板法（包括硬模板和软模板法）是制备纳米结构材料的常用方法,可用来制备多种物质的各种形状（如：球形粒子、一维纳米棒、纳米线、纳米管以及二维有序阵列等）的纳米结构,近年来关于这一领域的研究较为活跃。本文介绍了近年来利用氧化铝、二氧化硅、碳纳米管、表面活性剂、聚合物、生物分子等作模板制备多种物质的纳米结构材料的一些进展。     

原子转移自由基聚合接枝改性纳米Si02的研究进展

纳米SiO2粒子极易团聚,在有机介质中难以均匀分散,从而大大地限制了其优异性能的发挥,有必要对其进行化学改性处理。原子转移自由基聚合（atom transfer radical polymerization,ATRP）是对纳米Si02粒子进行接枝改性的一种有效途径,通过ATRP对纳米SiOz粒子进行表面改性,可以制备集无机纳米粒子和聚合物的优点于一身的SiO2-聚合物复合材料,且接枝链的长度及分子量分布可控,拓展了纳米SiO。的应用领域。本文主要综述了ATRP、RATRP（reverse ATRP）、AGETATRP（activators generated by electron transfer ATRP）和ARGETATRP（activators regenerated by electron transferATRP）方法对纳米Si02接枝改性的研究现状。     

聚合物纳米粒子的结构和性能对胞吞和细胞功能的影响

随着纳米医学的发展,越来越多的聚合物纳米粒子被用作荧光探针和药物或基因的载体,在生物分析、检测以及药物传输和基因治疗等领域得到应用。细胞的胞吞是细胞将细胞外基质、病毒、微组织或纳米粒子运送到细胞内部的一个重要生理过程。研究细胞对纳米粒子的胞吞,有助于从细胞层次上理解生命现象,掌握细胞内治疗的机理。本文综述了近几年来细胞和聚合物纳米粒子之间相互作用的最新研究结果。首先介绍了用于胞吞研究的常用聚合物纳米粒子体系及其功能化方法,尤其是荧光探针的复合与表面修饰。进而介绍了细胞和聚合物纳米粒子之间相互作用的基本过程,包括聚合物纳米粒子在细胞转运过程中的驱动力、细胞内转运过程、在细胞中的分布及其细胞毒性。对影响聚合物纳米微粒胞吞的因素如纳米粒子浓度、共培养时间、纳米粒子性能（形状、粒径、电荷和PEG修饰）、细胞类型和培养条件等进行了总结。最后重点介绍了用于受体介导细胞胞吞的聚合物纳米粒子体系,指出了目前研究工作中的不足及未来发展方向。     

二维金属-有机骨架膜的制备及其在分离中的应用

膜分离在面向能源与环境问题的分离过程中具有极大的应用前景, 近几十年内发展迅速. 金属-有机骨架(MOFs)是一种新型微孔材料, 具有孔结构均一、可调控、多样化的特点, 用其制备的MOF膜在分离领域极具应用潜力. 而二维(2D)材料的飞速发展, 使2D MOF膜也成为倍受关注的一类新型分离膜. 由2D MOF纳米片构筑成的超薄分离膜, 通过MOF的固有孔径可以实现分子级别的筛分, 而纳米片之间的通道及纳米片面内通道为气体或水分子提供了更多的传质通道, 从而实现了优异的分离性能. 因此, 2D MOF膜被认为有望同时提高分离过程的渗透量和选择性, 成为满足工业分离需求的高性能分离膜.     

高分子/单链高分子纳米粒子复合体系中的界面性质

高分子与纳米粒子复合是改善高分子材料性能的有效途径.近20年来关于高分子/纳米粒子复合物的研究引起了学术界广泛的兴趣.然而由于此类体系中的影响因素复杂,虽然学者们在相关材料性能的研究方面取得了重要进展,但是相关理论的发展却相对滞后,其中一个重要原因是实验上表征手段的缺失,导致对体系中纳米粒子与本体高分子链相互作用规律的认识(尤其是两者界面性质的认识)不够.本文总结和阐述了我们近几年利用分子动力学模拟技术研究高分子/单链高分子纳米粒子复合体系的主要结果,并围绕此类复合体系中的界面结构及动力学性质,讨论并总结了纳米粒子对本体高分子链的作用范围及影响规律,指出单链纳米粒子对熔体链的作用范围与纳米粒子的自身尺寸相当,而与熔体高分子链的分子量没有直接的关系.该结论将为纳米复合体系高分子理论的发展提供重要参考.     

Hybrid polymer/nanoparticle solar cells: preparation, principles and challenges

Hybrid polymer/nanoparticle solar cells have a light harvesting layer composed of semiconducting inorganic nanoparticles and a semiconducting conjugated polymer. They have potential to give high power conversion efficiencies (PCE). However, the PCE values reported for these solar cells are not currently as high as anticipated. This article reviews the main methods currently used for preparing hybrid polymer/nanoparticle solar cells from the colloid perspective. PCE data for the period of 2005-2011 are presented for hybrid polymer/nanoparticle solar cells and compared to those from polymer/fullerene cells. The key reasons for the relatively low PCE values for hybrid polymer/nanoparticle solar cells are uncontrolled aggregation and residual insulating ligands at the nanoparticle surface. Two hybrid polymer/nanoparticle systems studied at Manchester are considered in which the onset of aggregation and its affect on composite film morphology were studied from the colloidal perspective. It is concluded that step-change approaches are required to increase the PCEs of hybrid polymer/nanoparticle solar cells and move them toward the 10% value required for widespread commercialisation. A range of nanoparticles that have potential for application in possible longer term terawatt solar energy production are discussed.     

近红外响应硫化铜纳米粒子/液晶弹性体复合材料研究

报道了一种新型近红外响应光热转换试剂/液晶弹性体复合材料.目前绝大多数近红外吸收的无机金属纳米粒子,由于自身或其稳定剂(如长链硫醇或季铵盐)的化学性质,会致使经典的Finkelmann两步硅氢化加成反应中所使用的催化剂中毒失活,从而极大地限制了无机金属纳米粒子/液晶弹性体复合材料的拓展与应用.为了解决这一科学问题,我们采用了两步硫醇-烯点击化学快速制备单畴取向液晶弹性体薄膜的技术,将对近红外光有强吸收的油溶性硫化铜纳米粒子,成功地掺杂入聚硅氧烷液晶弹性体体系中,制备了近红外响应的硫化铜纳米粒子/液晶弹性体复合薄膜.通过使用紫外可见光谱、透射电子显微镜、扫描电子显微镜、偏光显微镜、示差扫描量热法、变温广角X射线散射对该复合材料进行了深入的研究,结果表明:该薄膜材料在980 nm近红外光源的照射下,可以实现高效的光热转换,从而实现快速、可逆的二维伸缩运动.     

Surface modification of ZIF-90 with triptycene for enhanced interfacial interaction in mixed-matrix membranes for gas separation

Zeolite imidazole framework (ZIF-90) nanoparticles were chemically modified by grafting triptycene moieties. The modified nanoparticles were introduced into a triptycene-based polyimide as fillers to generate mixed matrix membranes (MMMs) for gas separation. The incorporation of “hook-like” triptycene moieties in both dispersed and continuous phases led to intimate contact between the two phases and thus defect-free interfacial morphology, due to the supramolecular interlocking and π–π stacking interaction between triptycene units presented in both phases. The filler/polymer solution showed shear thickening behavior due to such strong interfacial interaction. The separation performance of the prepared composite membranes was investigated as a function of filler loading and particle surface grafting density. Pure-gas permeation results showed that the gas permeabilities increased expectedly as the filler loading increased, with stable or improved selectivities. The reduced permeability relative to pristine polyimide film is likely due to the pore blockage of ZIF-90 upon grafting triptycene moieties on the particle surface. Reducing the grafting density of triptycene moieties led to improved permeability and selectivity suggesting good tunability of this series of new composite membranes. Overall, modification of nanofiller with hierarchical triptycene moieties offers a fundamentally new avenue for creation of composite membranes with unique properties in gas separations.     

MICROPOROUS INORGANIC MEMBRANES

Recent development in microporous inorganic membranes represents a significant advance in materials for separation and chemical reaction applications. This paper provides an in-depth review of synthesis and properties of two groups (amorphous and crystalline) of microporous inorganic membranes. Amorphous microporous silica membranes can be prepared by the sol-gel and phase separation methods. Flat sheet, tubular and hollow fiber amorphous carbon membranes have been fabricated by various pyrolysis methods from polymer precursors. A large number of synthesis methods have been developed to prepare good quality polycrystalline zeolite membranes. Several techniques, including vapor and liquid approaches, are reviewed for pore structure modification to prepare microporous inorganic membranes from mesoporous inorganic membranes. Chemical, microstructural and permeation properties of these microporous membranes are summarized and compared among the several microporous membranes discussed in this paper. Theory for gas permeation through microporous membranes is also reviewed, with emphasis on comparison of theoretical with the experimental data. These inorganic microporous membranes offer excellent separation properties by the mechanisms of preferential adsorption, selective configurational diffusion or molecular sieving.     

Current Development and Challenges of Mixed Matrix Membranes for CO2/CH4 Separation

In the early stage of membrane technology development in gas separation, utilization of polymeric membranes has gained attention due to their robustness and ease of fabrication. However, the performance of polymeric membranes is limited by the trade-off between permeability and selectivity. Meanwhile, inorganic membrane is capable to exhibit great enhancement in separation performance but unfortunately its fabrication process is hard and costly. Thus, development of mixed matrix membranes (MMMs) by incorporating inorganic fillers into the polymer matrix has become a potential alternative to overcome the limitations of polymeric and inorganic membranes in gas separation. Nevertheless, fabrication of defect-free MMMs with improved separation performance and without compromising the mechanical and thermal stability is extremely difficult and challenging. In the current review paper, various types of inorganic fillers for MMMs fabrication and recent reported efforts to tailor the underlying problems on MMMs fabrication were discussed. The future outlook to advance the performance of MMMs in gas separation especially for CO₂/CH₄ separation was highlighted.     

Effect of hexagonal boron nitride on poly(vinyl phosphonic acid) composite polymer electrolytes for fuel cells

In this work, hexagonal boron nitride nanoparticles were used as inorganic fillers, which increase the mechanical and thermal stabilities as well as the proton conductivity of the proton conducting composite membranes prepared by blending of poly(vinyl phosphonic acid) and hexagonal boron nitride. Thermo gravimetric analysis showed that the polymer electrolyte membranes are thermally stable up to 200°C. Scanning electron microscopy analysis indicated the homogeneous distribution of boron nitride nanoparticles in the polymer matrix. The crystallinity of the membranes was characterized by using X-ray Diffraction. X-ray patterns support semi-crystalline nature of the composite materials.     

Composite nanoparticles: the best of two worlds

Nanomaterials have rapidly moved into the mainstream for chemical and biological analysis. Nanoparticle probes enhance signal intensity, increase the chemical and physical stability of the probe, and facilitate surface modification for specific targeting. Unfortunately, common problems are encountered with many nanoparticle probes, e.g., poor solubility, poor biocompatibility, and leakage of encapsulated components, that severely restrict the application of probes to ex vivo samples under carefully controlled conditions. A wide range of recently developed multifunctional nanomaterials are poised to make significant contributions to molecular analysis of biological systems. Composite nanoparticle geometries, including composites, hybrids, and core–shell nanoparticles prepared using two or more materials, e.g., silica/inorganic, silica/polymer, or polymer/inorganic combinations, offer improved solubility, easier functionalization, and decreased toxicity compared with the related single-component materials. Furthermore, composite nanomaterials present substantial signal amplification, and improved multiplexing for higher-sensitivity and higher-resolution measurements. Further development and integration of composite nanomaterials into the quantitative sciences will play a key role in the future of functional probes for imaging, quantitative analysis, and biological manipulation.     

Gas transport in TiO2 nanoparticle-filled poly(1-trimethylsilyl-1-propyne)

Titanium dioxide (TiO₂) nanoparticles were dispersed via solution processing in poly(1-trimethylsilyl-1-propyne) (PTMSP) to form nanocomposite films. Nanoparticle dispersion was investigated using atomic force microscopy and transmission electron microscopy. At low-particle loadings, nanoparticles were dispersed individually and in nanoscale aggregates. At high-particle loadings, some nanoparticles formed micron-sized aggregates. The gas transport and density exhibited a strong dependence on nanoparticle loading. At low-TiO₂ loadings, the composite density was similar to or slightly higher than that predicted by a two-phase additive model. However, at particle loadings exceeding approximately 7 nominal vol.%, the density was markedly lower than predicted, suggesting that the particles induced the creation of void space within the nanocomposite. For example, when the TiO₂ nominal volume fraction was 0.35, the polymer/particle composite density was 40% lower than expected based on a two-phase additive model for density. At low-nanoparticle loading, light gas permeability was lower than that of the unfilled polymer. At higher nanoparticle loadings, light gas permeability (i.e., CO₂, N₂, and CH₄) increased to more than four times higher than in unfilled PTMSP. At most, selectivity changed only slightly with particle loading.     

Nanocomposite membranes containing positively polarized gold nanoparticles for facilitated olefin transport

Positively polarized gold nanoparticles have been demonstrated for use as stable olefin carriers for facilitated olefin transport membranes. The formation and size of gold nanoparticles stabilized by 4-dimethylaminopyridine (DMAP) were monitored using X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–visible spectroscopy. Nanocomposite membranes that deliver high separation performance for olefin/paraffin mixtures were prepared by dispersing gold nanoparticles stabilized by DMAP in a polymer matrix, poly(vinyl pyrrolidone) (PVP). X-ray photoelectron spectroscopy (XPS) and zeta potential measurements revealed that gold nanoparticles stabilized by DMAP exhibited a high positive polarity, which is responsible for the reversible interaction between the gold nanoparticles and olefin molecules. Compared to neat PVP membranes, the composite membranes consisting of PVP and the polarized gold nanoparticles showed stable and enhanced separation of olefin/paraffin mixtures.