聚对苯二甲酸乙二醇酯/层状双氢氧化物纳米复合材料

聚对苯二甲酸乙二醇酯(PET)/层状双氢氧化物(LDHs)纳米复合材料是一种性能优异并具有广泛应用前景的新型聚合物基纳米复合材料.与纯PET相比, 其力学性能、热稳定性、阻燃性能与耐紫外线功能等均有明显提高或改善.本文对近年来PET/LDH纳米复合材料的研究进展进行了综述.首先, 对LDHs 的化学组成和结构特点进行了简要介绍, 并且对其制备方法和物理化学性质等进行了简单论述, 然后, 对PET/LDH纳米复合材料的制备、结构表征、结晶行为、机械力学性能以及耐热、阻燃和耐紫外线等功能性质的最新研究进展进行重点综述; 最后, 对其应用前景进行展望.     

聚丙烯酰胺/层状无机物纳米复合材料研究进展

聚丙烯酰胺(PAM)/层状无机物纳米复合材料相比于纯PAM具有更好的力学性能、超吸水性能、热稳定性能和气体阻隔性能等,是一种性能优异并在采油、农业和卫生学等领域有着广泛应用前景的新型聚合物基纳米复合材料。本文对近年来聚丙烯酰胺/层状无机物纳米复合材料的研究进展进行了综述。首先重点介绍了层状双氢氧化物(LDHs)在有机溶剂和水中剥离分散方面的研究进展,接着综述了PAM/LDH和PAM/粘土纳米复合材料的制备与结构表征,最后阐述了PAM/层状无机物纳米复合材料的流变性能、力学性能和超吸水性能等。     

聚乙烯醇/层状双氢氧化物纳米复合材料研究进展

聚乙烯醇/层状双氢氧化物纳米复合材料是近年来开发的新型聚合物基复合材料,表现出与纯聚乙烯醇基体明显不同的结晶行为,且具有良好的机械力学性能、耐热性能以及阻燃性能等,有着广泛的应用前景。本文首先对层状双氢氧化物的结构组成、制备方法和性质进行简要综述,然后着重介绍聚乙烯醇/层状双氢氧化物纳米复合材料的制备、结构表征、结晶行为、力学和热性能等方面的研究进展,最后对其应用前景进行展望。     

聚氯乙烯／热塑性弹性体共混增韧的研究进展

聚氯乙烯（PVC）是一种性能优良,价格低廉的通用树脂,但其脆性大、热稳定性差、加工性能不佳等,需要进行改性。通过用热塑性弹性体（TPE）对PVC进行共混增韧改性,可得到高性能的PVC复合材料。共混改性为PVC增韧改性的最简单易行的有效方法。本文概述了聚氯乙烯／热塑性弹性体共混体系的种类和制备方法,同时对影响热塑性弹性体...     

纳米双烃基复合金属氧化物的阻燃性能

研究了纳米尺寸双羟基复合金属氧化（MgAl-CO3-LDH)的结构及其对聚氯乙烯（PVC）复合材料的阻燃抑烟性能，通过X射线粉末衍射，扫描电子显微镜，热分析，粒度分析等手段对LDH进行了表征，结果表明，LDH粒径约为50－100nm，用透射电镜考察了LDH与PVC的复合物尺寸及形貌特征，得出改性的LDH在PVC中能以一次粒子均匀分散，将氧指数、UL－94垂直燃烧测试结果与文献值对比，实验所制备的纳米LDH对软PVC具有良好的阻燃效果，烟密度测试结果表明，纳米LDH是软LDH是软PVC良好的抑烟剂，每100份软PVC仅添加20－40份LDH，就可使软PVC的产烟速率及最大烟密度下降约40％。     

橡胶粒子和刚性纳米粒子对注塑级硬质聚氯乙烯复合材料断裂行为的影响

采用核壳型丙烯腈-苯乙烯-丁二烯共聚物(ABS)和纳米碳酸钙(CaCO3)协同改性聚氯乙烯(PVC),制备了注塑级硬质PVC纳米复合材料.通过透射电镜(TEM)、扫描电镜(SEM)、力学性能测试研究了其结构与性能,并采用有限元模拟方法研究了ABS与纳米CaCO3粒子对复合材料断裂行为的影响.当CaCO3含量低于12 p...     

离子交换法合成MTX/LDHs复合物的研究及体外细胞实验的探索

研究了不同水热温度下合成的层状双金属氢氧化物(layered double hydroxides,LDHs)对离子交换法制备的MTX/LDHs纳米复合物的影响.并利用透射电镜(TEM)、X-射线衍射(XRD)、MTT等手段,对纳米复合物的结构及载药量、控释-缓释性、生物细胞活性母体等性质进行了系统研究.结果表明,不同LDHs母体对离子交换后复合物的形貌和性质起着至关重要的作用.在磷酸缓冲液中考察了MTX/LDHs纳米复合物的药物控释性能并进行了动力学拟合,结果表明,采用离子交换法制备MTX/LDHs纳米复合物的释药过程是Fick扩散控制的离子交换和粒内扩散过程.最后,采用MTT法探究了MTX/LDHs纳米复合物对肺癌细胞A549增殖的抑制作用,结果表明,复合物较纯的MTX具有更好的抑制癌细胞增殖的作用.     

Zn/Al层状双氢氧化物-聚氯乙烯纳米复合物的制备与性能

用共沉淀法制备油酸钾改性的Zn2+、Al 3+层状双氢氧化物(Zn/Al-LDH),以环己酮为溶剂,用溶液插层法制备了Zn/Al层状双氢氧化物-聚氯乙烯(PVC)纳米复合物。采用傅里叶红外(FT-IR)、X-射线衍射(XRD)、透射电镜(TEM)对复合材料的结构及形貌进行了表征,并用热分析仪、万能试验机和紫外分光光度计研究了复合物的热稳定性能、拉伸性能和紫外吸收性能。结果表明:Zn/Al-LDH纳米片层无序分散在PVC基体中;Zn/Al-LDH对PVC低温时的骨干脱氯化氢有促进作用;与PVC膜相比,复合膜的分解温度降低,高温碳化温度升高,复合膜的拉伸强度及断裂伸长率得到提高,在300~380nm具有一定的紫外吸收性能。     

层状双金属氢氧化物基光催化剂的研究进展

层状双金属氢氧化物(LDHs)具有组分可调、层板金属离子高度分散、层间阴离子可交换、拓扑转变等特性,使其可作为理想的光催化剂、催化剂载体或前驱体。作为一种新型多功能材料,LDHs基光催化剂在环境净化、能源储备、工业催化和生物医学等多个领域广泛应用。但是,选择合适的路径进一步优化LDHs基光催化剂的性能,以实现太阳能的高效利用及催化反应过程的高转化率和高选择性仍然具有很大的挑战性。本文依据LDHs的结构特点及活性组分引入方式,将LDHs基光催化剂的制备方法总结归纳为主体层板构筑法、客体插层敏化法、剥离层层组装法、复合材料杂化法四类,详细介绍了不同制备方法对光催化性能的影响,综述其最新研究进展;并结合LDHs基光催化材料的应用,介绍其光催化行为和机理;最后,对LDHs基光催化剂的应用前景进行分析和展望。     

新型有机/无机复合紫外吸收剂的制备及其在PVC中的应用

将全波段紫外吸收剂聚苯并咪唑(PBI)与纳米SiO_2复配制备了有机/无机复合紫外吸收剂,用于改善聚氯乙烯(PVC)的紫外老化性能。为了增强纳米SiO_2与PBI之间的相互作用,先用硅烷偶联剂γ-氨丙基三乙氧基硅烷对纳米SiO_2改性,产物命名为MSiO_2,然后将PBI涂覆到MSiO_2表面得到复合填料PBI@MSiO_2,最后将填料与PVC通过溶体共混制备复合材料。使用紫外-可见分光光度计和万能拉伸试验机等对复合材料的紫外吸收性能和力学性能等进行了表征和对比分析。结果表明,PBI@MSiO_2粒子显著改善了复合材料的紫外吸收性能,375nm处的紫外吸收率可达99%;并改善了复合材料的力学性能和屈服强度,当PBI@MSiO_2质量分数为6%时,复合材料屈服强度可达63.3MPa。     

Structure-property relationships of new polystyrene nanocomposites prepared from initiator-containing layered double hydroxides of zinc aluminum and magnesium aluminum

Polystyrene/layered double hydroxides (PS/LDHs) nanocomposites were prepared by free radical polymerization of styrene monomer in the presence of LDHs intercalated with 4,4′-azobis(4-cyanopentanoate) anions (LDH-ACPA). XRD and ATR-IR are used to confirm that the materials produced are layered and the presence of the azo-initiator anions in these LDHs. These LDHs were used successfully to polymerize styrene and both XRD and TEM images of the composites support the formation of a mixed exfoliated-intercalated nanocomposite for ZnAl-ACPA but a microcomposite for MgAl-ACPA. The magnesium-containing LDHs decreased the glass transition temperature (T_g) of the composites while ZnAl-ACPA did not affect T_g significantly. The T_g depression is related to enhanced polymer dynamics due to the extra free volume at the LDH additive-polymer interface. A reduction in the onset of thermal decomposition temperature was observed in PS/LDH compared to neat PS, likely due to the early decomposition of the LDH. The fire performance, as evaluated by the cone calorimeter, reveal that PS-ZnAl-ACPA shows enhanced fire properties compared to PS-MgAl-ACPA.     

Hierarchical Structures Based on Functionalized Magnetic Cores and Layered Double‐Hydroxide Shells: Concept,Controlled Synthesis,and Applications

The combination of magnetic particles and layered double hydroxide (LDHs) materials leads to the formation of hierarchical composites that can take full advantages of each component; this is an effective approach for achieving multifunctional materials with intriguing properties. This Concept article summarizes several important strategies for the fabrication of magnetic‐core/LDH‐shell hierarchical nanocomposites, including direct coprecipitation, layer‐by‐layer assembly, and in situ growth methods. The obtained nanocomposites exhibit excellent performance as multifunctional materials for promising applications in targeted drug delivery, efficient separation, and catalysis. The fabrication and application of magnetic‐core/LDH‐shell nanocomposite materials represent a new direction in the development of LDH‐based multifunctional materials, which will contribute to the progress of chemistry and material science.     

PREPARATION OF POLY（METHYL METHACRYLATE）/LAYERED DOUBLE HYDROXIDES NANOCOMPOSITES via in situ SOLUTION POLYMERIZATION

An exfoliated layered double hydroxides/poly(methyl methacrylate)(LDHs/PMMA)nanocomposite was prepared by in situ solution polymerization of methyl methacrylate(MMA)in the presence of 4-vinylbenzenesulfonate intercalated LDHs(MgAl-VBS LDHs).MgAl-VBS LDHs was prepared by the ion exchange method,and the structure and composition of the MgA1-VBS LDHs were determined by X-ray diffraction(XRD),infrared spectroscopy and elemental analysis.XRD and transmission electron microscopy(TEM)were employed to examine the structure of LDHs/PMMA nanocomposite.It was indicated that the LDHs layers were well exfoliated and dispersed in the PMMA matrix.The grafting of PMMA onto LDHs was confirmed by the extraction result and the weight fraction of grafted PMMA increased as the weight fraction of LDHs in the nanocomposites increased.     

LDPE/Mg-Al layered double hydroxide nanocomposite: Thermal and flammability properties

Layered double hydroxides (LDHs) are new nanofillers which exhibit improved thermal and flammability properties in various kinds of polymer matrices. These materials have certain advantages over conventional metal hydroxides and also layered silicates so far as the flame retardancy is concerned. In this article, flammability and thermal properties of the nanocomposite based on low density polyethylene (LDPE) and Mg-Al based layered double hydroxide (Mg-Al LDH) are reported in detail. The nanocomposites containing different LDH concentrations were prepared by melt-compounding using a tightly intermeshing co-rotating twin-screw extruder. The morphological analysis reveals an exfoliated/intercalated type LDH particle morphology in these nanocomposites. The thermogravimetric analysis (TGA) shows that even a small amount of LDH improves the thermal stability and onset decomposition temperature in comparison with the unfilled LDPE. The heat release rate (HRR) and its maximum (PHRR) during cone-calorimeter investigation are found to be reduced significantly with increasing LDH concentration. The nanocomposites not only exhibit reduced total heat released (measure of propensity to produce long duration fire), but also lower tendency to fast fire growth (measured by the ratio of PHRR and time of ignition). The limited oxygen index (LOI) and the dripping behavior are also improved with increasing LDH concentration.     

乳液聚合法制备聚苯乙烯/Mg-Al层状双氢氧化物纳米复合材料

采用乳液聚合法制备阻燃性聚苯乙烯MgAl层状双氢氧化物(LDHs)纳米复合材料.通过对不同合成条件下复合材料的XRD谱,讨论了纳米复合材料的形成过程;经SEM图证实了LDHs是以剥离的纳米级层片分散在基体中的;TG和DSC谱图揭示了LDHs纳米层板可有效提高PS的热稳定性,并可使PS的玻璃化转化温度明显提高;当层状双氢氧化物在插层复合材料中含量为14.92%时,纳米复合材料的氧指数可达23.5%,其用量比在PS中直接添加纳米LDHs时要少约一倍.文中还分析了纳米复合材料的形成过程.     

The effect of OCoAl‐LDH and OCoFe‐LDH on the combustion behaviors of polyvinyl chloride

The effects of the modified layered double hydroxide (LDH) of Co/Al (OCoAl‐LDH) and the modified LDH of Co/Fe (OCoFe‐LDH) on the combustion behaviors of polyvinyl chloride (PVC) during pyrolysis processes were compared and investigated. The thermal degradation and combustion behavior of the PVC composites were investigated by thermogravimetric analysis (TGA), microscale combustion calorimetry (MCC), and cone calorimetry (CONE). The results indicate that the incorporation of LDHs brought about the improved thermal stability and reduced heat release of PVC composites at a high temperature. The smoke‐suppression properties of the composites are investigated by steady‐state tube furnace (SSTF), and the results indicated that the toxic gases such as CH₄, CO, and N_xO were inhibited by both of the two LDHs, but the OCoFe‐LDH has a better effect on the smoke suppression. Subsequently, the char layer was investigated by scanning electron microscopy–energy‐dispersive spectrometry (SEM‐EDS) and Raman analysis. The results indicate that the LDHs can promote the dechlorination of PVC during the thermal oxidation process and can inhibit the production of HCl in inert gas. Generally, OCoAl‐LDH and OCoFe‐LDH can be potential catalysts for waste disposal and can improve the fire safety of PVC.     

Elastomer/LDH nanocomposites: Synthesis and studies on nanoparticle dispersion, mechanical properties and interfacial adhesion

Layered double hydroxides (LDHs) based elastomer nanocomposites have been synthesized and characterized in terms of nanoparticle dispersion, mechanical properties and interfacial adhesion. Since LDH has basic hydroxyl groups on its surface, its potential as reinforcing filler in elastomers and in additionally a crosslinking agent in carboxylated elastomers has been investigated in details. For this purpose, two different elastomers having widely different polarities and functional groups (e.g., ethylene propylene diene terpolymer, i.e. EPDM and carboxylated nitrile rubber, i.e. XNBR) have been used as the matrix. The pristine LDH based on Mg and Al was modified with decane sulfonate by the regeneration method. The morphological analysis of the nanocomposites (done by X-ray diffraction analysis and electron microscopy) shows that in both matrices LDH particles are dispersed in three different forms, i.e. as primary particles, as exfoliated layers and as soft clusters formed by both of them. However, their relative proportion differs drastically in the two matrices. We have shown in this study that the LDH can significantly improve the mechanical properties in both the system. In XNBR/LDH nanocomposites containing no conventional metal oxide curative, this improvement is very prominent due to secondary interaction between LDH and XNBR matrix indicating that LDH can crosslink carboxalated elastomers. It is also observed that LDH particle promotes strain-induced crystallization in XNBR/LDH. The fracture surface analysis shows that in XNBR/LDH nanocomposite very stable polymer-filler interface is formed and tensile failure takes place through the matrix rather than through the interface. In case of EPDM/LDH nanocomposites the opposite is observed and the polymer matrix hardly wets the surface of the LDH particle.     

Evaluation of Organically Modified Layered Double Hydroxides as Fillers for the Preparation of Polymer Nanocomposites in Miniemulsion Polymerization

Latexes of poly(n‐butyl acrylate‐co‐methyl methacrylate) [P(BA‐co‐MMA)] filled with magnesium–aluminum layered double hydroxides (MgAl‐LDHs) are synthesized using miniemulsion polymerization. Three commercial LDHs organically modified with different types of anions are used as fillers (Perkalite F100S, Perkalite A100, and Perkalite AF50) and three different types of surfactants are tested to stabilize the miniemulsions including a cationic, an anionic, and a nonionic one. Stable LDH‐containing miniemulsions are prepared with a mixture of sodium dodecyl sulfate and Triton X‐405 and the polymerizable co‐stabilizer octadecyl acrylate. They are then polymerized to yield nanocomposite latexes. Depending on the type of LDH used, the presence of the inorganic material in the reaction medium affects the polymerization kinetics. X‐ray diffraction analysis of the resulting nanocomposite films suggests exfoliation of the inorganic material. The glass transition temperature of the nanocomposites is not affected by the LDHs and the decomposition temperature of the nanocomposites determined by thermogravimetric analysis is greater than that of the pure polymer.