纳米片层填充型高阻隔性复合薄膜研究进展

聚合物包装材料在易变质产品领域的应用受到很大的限制,提高其气体阻隔性能成为研究热点。纳米片层填充法能够有效地利用"多路径效应"和"可渗透面积减少效应"提高聚合物包装材料的气体阻隔性能。纳米片层的填充使气体在聚合物中的扩散系数和溶解度系数下降,从而降低气体渗透系数,提高聚合物的气体阻隔性能。常见的纳米片层包括蒙脱土和石墨烯(或氧化石墨烯)。制备纳米片层填充型高阻隔复合薄膜的方法有2种:调整加工外场来调控纳米片层在聚合物基体中的取向程度;对纳米片层表面基团功能化来提高填料与基体的界面结合作用。今后的研究应致力于使用可生物降解的绿色材料制备高阻隔性聚合物包装薄膜。     

聚合物/层状矿物纳米复合材料的研究进展

聚合物/层状矿物纳米复合材料结合了聚合物的强韧性与纳米层状矿物的强力学性,具有优良的力学性能、热学性能、气体阻隔性能和导电性能等,实际应用广泛。介绍了聚合物/层状矿物纳米复合材料结构特点及其表征方法和制备方法、性能和应用,并综述了近年来聚合物/层状矿物纳米复合材料的研究进展,展望了该类材料的发展趋势。为了进一步加快该类材料的发展,应进一步从分子尺度上全面理解聚合物/层状矿物纳米复合材料的结构,尤其是聚合物主体与层状矿物片层间界面结构与性质对纳米复合材料整体性能的影响。     

水滑石/丁腈橡胶纳米复合材料的制备及性能研究

采用乳液复合法制备水滑石(LDHs)/丁腈橡胶(NBR)纳米复合材料,并对其结构和性能进行研究。结果表明:复合材料中LDHs均匀分散在NBR基体中;与NBR胶料相比,LDHs/NBR复合材料的物理性能和气体阻隔性能明显提高;当LDHs/NBR用量比为1/20且LDHs用量为1份时,LDHs/NBR复合母胶/溴化丁基橡胶并用胶的气体阻隔性能较好。     

聚合物纳米复合材料应用现状

与常规填料相比，纳米填料在用量大幅度降低的同时还可提高聚合物材料的力学性能、气体阻隔性能、阻燃性能和导电性能，因此其在塑料领域具有巨大的应用潜力。     

聚苯乙烯-丙烯腈/蒙脱土纳米复合材料的制备和结构

引 言 近年来,聚合物/蒙脱土纳米复合材料已成为材料科学界的一个研究热点,各种高分子材料均被尝试用来制备此类纳米复合材料以提高聚合物的力学性能、热性能和阻隔性能[1-4].对聚合物/蒙脱土纳米复合材料的研究主要集中在制备方法、结构和性能表征方面,如何利用蒙脱土片层的特性来探索简单易行、成本较低且能够使蒙脱土充分剥离分散的方法一直是此方面的研究焦点.     

基于AB型环糊精主客体相互作用的超分子聚合物的研究进展

对环糊精的羟基进行选择性衍生化,可以调节环糊精分子与客体分子的络合特性。文章综述了各类基于环糊精主客体相互作用的的组装单体,通过自组装可以形成不同拓扑结构的超分子聚合物组装体。     

半纤维素改性制备膜材料

分析和概述了近年来半纤维素改性制备薄膜材料的最新研究成果。从其潜在的两个应用方面——食品包装材料和可食用包覆膜出发,分别在隔氧性、阻湿性、机械性能等方面对不同改性方法制备的半纤维素薄膜和传统的聚合物薄膜材料作了详细的比较。改性半纤维素膜具有可再生及生物降解性能,其阻隔性能与传统聚合物薄膜材料相当,可望成为一种具有广阔市场前景的新型环保材料。     

金属表面纳米粒子/聚合物复合防腐涂层的研究进展

纳米材料（NMs）具有独特的性能，由其构成的纳米粒子/聚合物复合涂层在金属表面防腐蚀方面是非常经济有效的。本文总结了氧化物基和碳基两种不同纳米材料对纳米粒子/聚合物涂层性能的影响，概述了典型纳米粒子/聚合物复合防腐涂层防腐机理，表明碳基纳米材料可以作为提高防腐涂层阻隔性能的较有前途的纳米填料。最后展望了将纳米粒子/聚合物材料有效应用到金属表面防腐涂层中所面临的挑战和未来发展前景。     

基于多尺度结构与界面工程调控的高储能密度聚合物基电介质复合材料

电介质材料是决定电介质电容器储能特性的关键材料。聚合物基复合电介质因综合了聚合物基体和改性填料的独特优势已成为目前极具发展潜力的储能电介质材料。然而,当前高度集成化和小型化的能源动力系统对电介质电容器的储能性能提出了更高的要求,而改善性能的根本在于进一步提升聚合物基复合电介质的储能密度。本工作比较了不同种类聚合物基电介质复合材料的性能特征,总结了其结构特点和设计思路,从多尺度结构和界面工程调控等方面回顾了提升复合电介质储能性能的方法,包括调控填料的微观结构、构建宏观层状结构、纳米涂覆聚合物表面、聚合物分子结构设计等策略。最后,总结了当前聚合物基复合电介质材料面临的挑战和未来的发展趋势。     

层层自组装技术制备类水滑石基新型薄膜材料的研究进展

类水滑石（layered double hydroxides,LDHs）具有各向异性的结构特征、特殊的理化特性及多功能性,在材料科学领域得到广泛应用。本文围绕近年来LDHs基薄膜材料的研究进展,系统概括了层层自组装技术（layer-by-layer self-assembly,LBL技术）制备的LDHs基新型薄膜材料的基础作用力（如静电吸附作用、氢键作用等）,阐述了LDHs与无机分子（如蒙脱石、二氧化锰、石墨烯等）、有机分子（如聚乙烯醇、荧光染料、聚苯乙烯磺酸盐等）等组装制备的特性薄膜材料,并总结了其在光、电、催化、生物无机材料等方面的应用。指出伴随着制备方法、化学组成及成膜作用力等方面基础研究的深入以及对LBL技术的功能化、实用化研究的日臻成熟,以LBL技术构筑的LDHs基薄膜材料必将对材料、化学、生物等科技领域产生深远的影响。     

Polymer nanocomposites using zinc aluminum and magnesium aluminum oleate layered double hydroxides: Effects of LDH divalent metals on dispersion, thermal, mechanical and fire performance in various polymers

Oleate-containing layered double hydroxides of zinc aluminum (ZnAl) and magnesium aluminum (MgAl) were used to prepare nanocomposites of polyethylene, poly(ethylene-co-butyl acrylate) and poly(methyl methacrylate). The additives and/or their polymer composites were characterized by X-ray diffraction, FTIR, elemental analysis, thermogravimetric analysis, mechanical testing, and cone calorimetry. The unusual packing of the monounsaturated oleate anions in the gallery of these LDHs facilitates the dispersion of these nanomaterials. The inorganic LDH protects the polymer from thermal oxidation, shown by enhancement of the thermal and fire properties of the corresponding polymer nanocomposites. There is a qualitative difference in the morphology of the two LDHs in PE and PMMA. ZnAl is better dispersed in PE while MgAl is better dispersed in PMMA. The zinc-containing material led to a large reduction in the peak heat release rate in polyethylene, while the magnesium-containing material led to enhancement of the fire properties of the more polar poly(methyl methacrylate). These fire properties are consistent with the morphological differences. Neither of these LDHs shows efficacy with poly(ethylene-co-butyl acrylate), which indicates a selective interaction between the LDH and the various polymers.     

Preparation of PET/LDH composite materials and their mechanical properties and permeability for O2

The terephthalate‐intercalated LDHs (TA‐LDHs) are used to improve the barrier properties of poly(ethylene terephthalate) (PET) for their application in liquid food packaging. First, TA‐LDHs were synthesized from freshly prepared metal hydroxides. PET/LDH nanocomposites were then prepared by a masterbatch process. The structures and morphologies of TA‐LDHs and PET/LDH nanocomposites were characterized using X‐ray diffractometer, transmission electronic microscopy, and scanning electron microscope. The mechanical performances and the oxygen permeability of the PET/LDH composites were measured using a precision universal tester and differential pressure gas permeameter, respectively. The influence of TA‐LDH content on their structures and properties was studied. PET/LDH nanocomposites with 1 and 2 wt% of TA‐LDHs are partially exfoliated nanocomposites, while PET/LDH with 5 wt% of TA‐LDHs is an intercalated nanocomposite. The PET/LDH nanocomposites prepared by a masterbatch process show better mechanical properties and gas barrier properties. PET/LDHs‐m2 with 2 wt% of TA‐LDHs could offer up to a 29.4% improvement in tensile strength over PET and the Young's modulus is increased by 38.9%. The O₂ permeation of PET/LDHs‐m2 with 2 wt% of TA‐LDHs is decreased by 46.2%. POLYM. ENG. SCI., 59:E366–E371, 2019. © 2019 Society of Plastics Engineers     

Facile construction of cellulose/layered double hydroxides nanocomposite membranes with high strength and antibacterial properties

High-strength regenerated cellulose/ZnAl-layered double hydroxides (LDH) composite membranes (RCL) with good mechanical and antibacterial performance were developed by stirring vigorously cellulose and LDH in NaOH/urea aqueous solvent system at −12°C. The obtained cellulose/LDH composited materials were characterized and the results indicated that well dispersion of LDH in the cellulose matrix. The tensile strength of RCL membranes were enhanced to 92.1 MPa from 68.3 MPa for that of RC film because of the strong interfacial interaction between the LDHs and cellulose matrix as well as the high rigidity of the LDHs. The addition of LDH into the cellulose could improve the thermal stability, water resistance, and flame retardant of the regenerated cellulose film. Zn²⁺ ions were exited in the cellulose/ZnAl-LDH materials, leading to good antibacterial activities against Staphylococcus aureus and Escherichia coli, which is important for RCL composite materials in antibacterial packaging filed.     

Organic Host Materials for Solution-Processed Phosphorescent Organic Light-Emitting Diodes

As a new technology for flat-panel displays and general lighting sources, solution-processed phosphorescent organic light-emitting diodes (PhOLEDs) unfurl a bright future, due to their merits of high quantum efficiency and easy fabrication. In recent years, great progress has been made in the device performance of solution-processed PhOLEDs, by developing both high-efficiency organometallic phosphors and novel solution-processable organic host materials. This review highlights recently developed organic host materials for triplet guest emitters in solution-processed PhOLEDs. The solution-processable host materials are classified into three types – small molecule, dendrimer, and polymer – according to their molecular architecture and molecular weight. The material design concept and the relationships between the molecular structure, material properties and device performance are the focus of this discussion. A future strategy for the development of high-performance solution-processed host materials is proposed.     

Inorganic layered double hydroxides as a drug delivery system—intercalation and in vitro release of fenbufen

Layered double hydroxides (LDHs), or so-called anionic clays, consist of cationic brucite-like layers and exchangeable interlayer anions. Because of their biocompatibility, some LDHs, such as Mg/Al, Zn/Al, Fe/Al and Li/Al-LDH, can be used as host materials for drug-LDH host–guest supramolecular structures. The anti-inflammatory drug fenbufen has been intercalated into layered double hydroxides for the first time by co-precipitation under a nitrogen atmosphere. The product has been characterized by powder X-ray diffraction (XRD), FT-IR spectroscopy, elemental analysis and thermogravimetry (TG) and shows an expanded LDH structure, indicating that the drug has been successfully intercalated into LDH. In addition, the dependence of the nature of the fenbufen intercalation process on conditions such as pH value and chemical composition of the host has been systematically investigated. The interlayer distance in the intercalated materials increases with increasing pH value, resulting from a change in the arrangement of interlayer anions from monolayer to interdigitated bilayer. Drug release characteristics of the pillared LDH materials were investigated by a dissolution test in a simulated intestinal fluid (buffer at pH 7.8). The results show that the drug release of supramolecular LDH materials was a slow process, especially in the case of Mg/Al intercalated materials, suggesting that these drug-inorganic hybrid materials can be used as an effective drug delivery system.     

Advances in layered double hydroxide (LDH)-based elastomer composites

This article reviews the advances in layered double hydroxide (LDH) materials and the synthesis of LDH-based elastomer composites. The potential of tuning the structure of LDH materials for desired properties and applications has attracted both academic and industrial interest in recent years. The modification of LDH materials and the use of such materials in the synthesis of composites with different elastomer matrices have been critically analyzed. Emphasis has been given to the use of Mg-Al LDHs and Zn-Al LDHs with different elastomers. The use of modified LDHs with elastomers substantially improves their mechanical, thermal and optical properties. Even “smart properties” of elastomers, such as reversible thermotropic optical characteristics, have been realized with the use of LDH-based multifunctional additives in rubber formulations. The flame retardance of some elastomer composites has also been enhanced with the use of modified LDHs. The possibility of replacing ZnO with LDH during rubber compounding has also been discussed, which would lead to drastic interventions in the well-established rubber processing technologies. LDH materials have also been reported to be biocompatible. Therefore, among the various possible applications of LDHs in different material development processes, their use in rubber technology offers the potential for environmentally friendly rubber products, even tires. Throughout this article, the structure, synthesis, properties and applications of elastomer/(LDH) composites are discussed, including suitable examples taken from the relevant literature.     

Facile synthesis of NiAl-layered double hydroxide/graphene hybrid with enhanced electrochemical properties for detection of dopamine

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach.     

Synthesis of p-sulfonated calix[4]arene-intercalated layered double hydroxides and their adsorption properties for organic molecules

Calixarenes are macrocyclic organo anions, which cavity is capable of molecular recognition, while layered double hydroxides (LDHs) are widely known as hydrotalcite-like compounds, anion exchangers and host–guest materials. In this study, the intercalation of water-soluble p-sulfonated calix[4]arene (CS4) in the interlayer of the Mg–Al and Zn–Al LDHs (M²⁺/Al ratio = 3) by the coprecipitation method has been investigated as well as the adsorption property of the resulting CS4/LDHs for benzyl alcohol (BA) and p-nitrophenol (NP). It was found that the CS4/LDHs with the molar ratio of CS4/Al = 0.25 (Mg–Al LDH) and 0.12 (Zn–Al LDH) were obtained as a single phase. The arrangement of CS4 in the LDH interlayer was different by the kind of the host metal ions as CS4 cavity axis perpendicular (Mg–Al LDH) and parallel (Zn–Al LDH) to the basal layer, influencing strongly on the BET surface area, N₂ adsorbed volume and adsorption property for BA and NP.