不同工艺有机插层蛭石的制备及表征

以两倍蛭石阳离子交换容量的十六烷基三甲基溴化铵为插层剂,利用热液搅拌法、球磨法、煮沸法、熔融搅拌法四种不同的工艺对蛭石进行插层处理,对有机插层蛭石进行了X射线粉晶衍射、傅里叶变换红外光谱仪和热重分析表征,结果表明随着不同工艺的插层条件会导致有机插层蛭石层间距的变化,并且随着层间距的增大,蛭石层间的有机相含量逐渐增大。     

有机蛭石的制备工艺与催化性能

为了研究制备工艺对蛭石有机化效果的影响以及有机蛭石在催化领域的应用,以硝酸为酸化剂,氯化钠为钠化剂,十六烷基三甲基溴化铵为插层剂,采用"酸化-钠化-插层"工艺制备了有机蛭石,并研究了有机蛭石对高密度聚乙烯基复合材料的催化作用;探讨了了不同硝酸、氯化钠浓度和十六烷基三甲基溴化铵用量对有机化效果的影响。有机蛭石的XRD和阳离子交换容量(CEC)测试表明,采用0.1mol/L的硝酸,饱和浓度的氯化钠和1.5倍蛭石CEC的十六烷基三甲基溴化铵时,插层效果最佳。高密度聚乙烯基复合材料的热降解分析测试显示,有机蛭石对高密度聚乙烯-膨胀型阻燃剂复合材料的交联成炭反应有催化作用。     

有机蛭石的制备与应用研究现状

从蛭石的晶体化学特征出发,在探讨蛭石有机改性原理的基础上,评述了有机蛭石的改性方法与特点,以及改性蛭石在环境保护和纳米复合材料方面的应用.蛭石层间阳离子的可交换特性是使有机阳离子插入到层间域的驱动力;采用胺盐和有机大分子可获得不同层间距的插层有机蛭石;有机改性蛭石可作为有机污染物的良好吸附剂,也是制备聚合物/蛭石纳米复合材料的前驱体.     

有机蛭石/酚醛树脂熔融插层纳米复合材料的研究

用十六烷基三甲基溴化铵对膨胀蛭石进行了有机化处理,并用熔融法制备了有机蛭石/酚醛树脂插层纳米复合材料.通过XRD,AFM,TGA测试分析了所制备的复合材料的结构与热性能.结果表明:酚醛树脂能插层于蛭石片层中,制得的蛭石/酚醛树脂插层纳米复合材料的耐热性有了很大程度的提高.     

聚氨酯/有机改性蛭石复合材料的制备及性能研究

聚合物/层状硅酸盐复合材料是近年来比较广泛应用的新型材料。以十八烷基三甲基溴化铵(OTAB)改性蛭石作为前驱体,通过高速搅拌-超声分散法将聚碳酸酯多元醇(PCDL)分散到蛭石层间作为软段,以1,4-环己烷二异氰酸酯(CHDI)为硬段,通过插层聚合得到聚氨酯/有机改性蛭石复合材料。利用FT-IR、XRD、TGA、SEM和拉伸强度测试等对有机改性蛭石进行结构表征,并且对复合材料的性能进行了探讨。研究表明,蛭石通过有机改性,层间距增大到2.37nm,PCDL超声分散后层间距进一步增加到2.92nm。复合材料的力学性能明显增强,拉伸强度为26.8 MPa,比纯聚氨酯增加了52.3%,复合材料抗温可达到300℃。     

蛭石的改性——有机蛭石的碳化

以十六烷基三甲基溴化铵(CTAB)为有机试剂,通过溶液法将其插入蛭石层间,制得有机改性蛭石(O-Ver).使用X-粉晶衍射仪、差热分析仪研究蛭石、有机改性蛭石煅烧过程中的变化情况,确定碳化工艺,而后在一定条件下对O-Ver进行高温煅烧,使蛭石层间的CTAB碳化,制备碳夹层式的碳-蛭石复合材料.用所制得的碳-蛭石复合材料与天然橡胶复合制备天然橡胶/碳-蛭石复合材料.通过用高阻仪、氧指数测定仪分析测试,结果表明,天然橡胶/碳-蛭石复合材料的导电率增大,抗静电能力增强.因此,说明碳化的O-Ver改善了蛭石的电学性能,同时该材料较好地改进了橡胶的电学性能.     

剥分蛭石包覆聚酰亚胺复合材料及性能研究

采用四甲基溴化铵和十六烷基三甲基溴化铵对蛭石进行有机膨胀和机械剥分,研究剥分蛭石包覆聚酰亚胺(PI)复合材料的耐热性能。采用傅里叶变换红外光谱(FTIR)和热重分析(TG)证明有机插层剂成功插入蛭石层间,采用小角X射线衍射(XRD)和扫描电子显微镜(SEM)表征不同蛭石样品的微观结构及剥分情况。剥分蛭石包覆聚酰亚胺复合材料的热隔绝性能和耐形变性由温差测试实验测定。     

有机插层蛭石功能材料的制备与表征研究

用十六烷基三甲基溴化铵(HDTMA·Br)对蛭石矿物进行插层改性,制成有机插层蛭石功能材料。应用X射线衍射分析、差热分析等对有机插层蛭石结构进行表征。结果显示,HDTMA可较容易进入蛭石矿物的层间域中,HDTMA以倾斜立式在层间排列,倾角约为57°。蛭石与HDTMA之间的反应,在HDTMA加入量较少时以离子交换为主;在HDTMA加入量较多时,分子吸附也变得重要。当HDTMA加入量小于蛭石的阳离子交换容量时,HDTMA将尽量以紧密排列方式进入部分蛭石层间,进入蛭石层间域的HDTMA具有较好的稳定性,不易解吸。     

聚乳酸/蒙脱石纳米复合材料的制备与表征

对纳基蒙脱石(MMT)有机改性后,采用溶液插层薄膜塑造工艺制备蒙脱石/聚乳酸(PLA)纳米复合物,采用X-Ray粉晶衍射(XRD)、综合热分析(TGA&DSC)、红外吸收光谱(IR)等方法对复合材料进行表征,讨论了蒙脱石对插层结果的影响.结果表明,PLA能够插入MMT层间;MMT的层间距由1.40nm增大到2.16nm;复合材料的热稳定性能得到改善.     

CO_2插层作用下有机蒙脱土膨胀/结构行为的分子模拟

运用蒙特卡洛分子模拟方法,依据能量最小原则,从微观水平研究了二氧化碳环境下钠蒙脱土及表面活性剂改性有机蒙脱土的膨胀性能和层间结构。模拟结果表明,蒙脱土晶面间距随着层间二氧化碳含量增加而膨胀增大,其中有机蒙脱土表现出更强烈的膨胀性能。通过结构分析,层间二氧化碳随着蒙脱土晶面间距的增大而出现明显的多层分布现象,其中层间表面活性剂随着二氧化碳含量的变化而形成不同的结构形态。     

pH sensitive organic-inorganic layered nanomaterials by self-assembly of indigocarmine between the inorganic layers

New pH sensitive organic-inorganic intercalation compounds having different interlayer spacing were prepared. Zn-Al layered double hydroxide (LDH) is an anion exchangeable inorganic layered compound whose interlayer spacing is 0.76 nm. In the reactions of indigocarmine (IDC) with the calcined Zn-Al LDH at pH = 7 (LDH-IDC7), interlayer spacing increased to 2.25 nm. The interlayer spacing of LDH-IDC7 decreased to 1.89 nm by the treatment in basic solution. In the reaction of IDC with the calcined Zn-Al LDH at pH = 10 (LDH-IDC10), interlayer spacing of the intercalation compounds was 1.89 nm. The interlayer spacing of these intercalation compounds was changed reversibly by the treatments in acidic or basic solution.     

插层型蔗糖/蛭石纳米复合材料的制备

以蔗糖和蛭石为原料,在超声辅助条件下采用溶液插层法制备插层型蔗糖/蛭石纳米复合材料。X射线衍射（XRD）、红外光谱（FTIR）分析表明,蔗糖/蛭石复合物样品的d001值为1.852nm;样品的红外谱图中出现甲基和亚甲基特征峰2761cm-1和2969cm-1。将蔗糖/蛭石复合物在氮气氛下碳化后,样品的XRD（d001=1.247nm）和红外光谱结果（甲基和亚甲基特征峰2761cm-1和2969cm-1消失）表明,碳/蛭石复合材料层间夹有碳,进一步证实得到插层型蔗糖/蛭石复合材料。同时,确定了优化插层反应工艺条件,超声功率为400W,物料配比为蛭石：蔗糖=1：2.5,超声水化时间为0.5h,超声反应温度为70℃,反应时间为2.5h,静置时间2h。     

Super-high interlayer spacing of graphite oxide obtained by γ-ray irradiation in air

We produced a type of graphite oxide with the interlayer spacing of 2.09 nm by treating conventional graphite oxide with γ-rays at an absorbed dose of 200 kGy in air. The expansion of interlayer distance should be attributed to the increased amounts of topological defects and then the improved steric hindrance between interlayers. Due to the decomposition of water molecules in graphite oxide by γ-rays, the reductive species were produced so that graphite oxide was partially reduced. It is also speculated to be the main mechanisms for alteration of oxygen groups. The change of carbon chain structures and oxygen groups were further supported by X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. This simple and effective method of making graphite oxide with d-spacing of 2.09 nm by irradiating it in air is of interest not only for its easier intercalation and exfoliation than pristine one, but also for its potential to prepare graphene sheets with high percent of monolayers.     

阳离子表面活性剂对钠基蒙脱土的插层改性研究

用十八烷基三甲基氯化铵(OTAC)通过离子交换法对钠基蒙脱土成功进行了有机化插层改性. 红外分析结果表明: OTAC与蒙脱土之间发生了反应, X射线衍射(XRD)分析结果显示随OTAC浓度的提高, 蒙脱土的(001)晶面间距逐渐扩大, 最大值可增至3.80 nm; 基于以上分析研究, 假定了OTAC分子在蒙脱土片层间的排列分布状态. 扫描电镜(SEM)观察到改性前后蒙脱土的表面形貌发生了显著变化, 改性前蒙脱土团聚成大小不一的致密堆积颗粒, 而改性后的蒙脱土被剥离为松散的鱼鳞片状; 接触角测试和沉降实验结果表明, 改性后钠基蒙脱土的表面润湿性由亲水性转变为亲油性.     

剥离型纳米蒙脱土/聚酰亚胺复合材料的制备与表征

利用二苯基甲烷-4,4’-二异氰酸酯（MDI）与酸化的蒙脱土（MMT）表面的羟基进行反应制得了MMT-MDI;进一步利用己内酰胺（CPL）对MMT-MDI进行插层并对多余的异氰酸酯端基进行封端,制得了MMT-MDI-CPL。采用预聚体溶液插层法,利用聚酰胺酸（PAA）在二甲基乙酰胺（DMAC）溶剂中分别对MMT-MDI和MMT-MDI-CPL进行预聚体插层,制得了剥离型纳米MMT/聚酰亚胺（PI）复合材料。通过电感耦合等离子体发射光谱（ICP-OES）、FTIR、TG、XRD和SEM对改性MMT和纳米MMT/PI复合材料进行了表征。结果表明：MDI与MMT表面羟基反应而被成功接枝于MMT上;MDI对MMT的改性、CPL对MMT-MDI的插层和封端使MMT层间距得到逐步扩大;MMT/PI复合材料的XRD和断面SEM表明,MMT在PI基体中得到了充分剥离。     

聚苯乙烯/氧化石墨纳米复合材料的制备与性能

利用十六烷基三甲基溴化铵对氧化石墨进行插层改性。以原住插层聚合的方式合成了聚苯乙烯／氧化石墨（PS／GO）纳米复合材料。用XRD和TEM进行的形态研究表明,氧化石墨被剥离成10nm-30nm厚的层片而分散在聚合物基体中。热重分析证明PS／GO复合材料比PS材料和普通石墨粉填充的PS材料表现出更好的热稳定性。     

Fabrication and optical properties of photochromic compound/clay hybrid films

A cationic spiropyran iodide derivative (SPI) was synthesized as a photoresponsive compound, and SPI/montmorillonite clay hybrid films were prepared using ion- and guest-exchange intercalation methods. When the ion-exchange method was applied to clay with a low cation-exchange capacity (CEC), intercalation of SPI into clay interlayers did not occur. Using the clay with a high CEC, SPI was intercalated into clay interlayer and the interlayer distances were elongated. Upon UV and visible light irradiation, SPI in hybrid film photoisomerized reversibly and the interlayer distance also changed reversibly. On the other hand, intercalation by the guest-exchange method using cethyltrimethylammoniumbromide (CTAB) as a pre-exchanging reagent was independent on the CEC. After the addition of SPI, the CTAB in the clay interlayers was exchanged for SPI, but a partial CTAB remained in the interlayer. SPI in the hybrid films prepared by the guest-exchange method photoisomerized reversibly without any change in interplanar distance due to the coexisted CTAB.     

Synergistic Interlayer and Defect Engineering in VS2 Nanosheets toward Efficient Electrocatalytic Hydrogen Evolution Reaction

A simple one‐pot solvothermal method is reported to synthesize VS₂ nanosheets featuring rich defects and an expanded (001) interlayer spacing as large as 1.00 nm, which is a ≈74% expansion as relative to that (0.575 nm) of the pristine counterpart. The interlayer‐expanded VS₂ nanosheets show extraordinary kinetic metrics for electrocatalytic hydrogen evolution reaction (HER), exhibiting a low overpotential of 43 mV at a geometric current density of 10 mA cm^?2, a small Tafel slope of 36 mV dec^?1, and long‐term stability of 60 h without any current fading. The performance is much better than that of the pristine VS₂ with a normal interlayer spacing, and even comparable to that of the commercial Pt/C electrocatalyst. The outstanding electrocatalytic activity is attributed to the expanded interlayer distance and the generated rich defects. Increased numbers of exposed active sites and modified electronic structures are achieved, resulting in an optimal free energy of hydrogen adsorption (?G_H) from density functional theory calculations. This work opens up a new door for developing transition‐metal dichalcogenide nanosheets as high active HER electrocatalysts by interlayer and defect engineering.