埃洛石纳米管的应用研究现状

埃洛石纳米管是一种新型的纳米材料,价廉易得且具有优异的性能,目前对它的研究是国际材料领域的前沿和热点,与碳纳米管相比它具有独特的结构特点和明显的资源优势。本篇综述回顾了埃洛石纳米管的应用研究进展,扼要介绍了埃洛石纳米管的化学组成及晶体结构。埃洛石纳米管的功能与其结构特点息息相关,文章以它对水、甲醇、乙醇等氢键流体的输运性能、对燃料气体的储存容纳、对药物大分子微胶囊包裹以及作为治理环境吸附剂等为例,浅谈它在物质吸附、储存、输运方面的应用;以它作为重油催化裂化的催化剂和酶及金属氧化物的催化剂载体为例,浅谈在催化方面的应用。最后,对高岭土资源的有效开发利用以及埃洛石纳米管应用研究领域的未来方向提出了一些设想。     

聚吡咯/聚苯胺二元复合纳米管及其热电性能

以甲基橙为软模板,六水合三氯化铁为催化剂,在水溶液中通过沉淀聚合法制备了管径为20～180 nm的聚吡咯(PPy)纳米管;以聚吡咯纳米管为基体,通过原位聚合制备了聚吡咯/聚苯胺(PPy/PANi)二元复合纳米管.研究发现,在PPy/PANi二元复合纳米管中,PANi均匀地包覆在PPy纳米管表面,并形成有序堆积,PPy与PANi间存在强烈的π-π共轭作用与氢键作用,当PPy与PANi单体摩尔比为1∶2时,PPy/PANi二元复合纳米管的功率因子在363 K时达到0. 74μW/(m·K²).     

光谱法研究埃洛石纳米管与溶菌酶间的相互作用

以溶菌酶作为模型蛋白,主要利用光谱法研究了埃洛石纳米管与溶菌酶之间的相互作用。荧光光谱结果表明向溶菌酶体系中加入埃洛石纳米管会出现荧光猝灭现象,猝灭机理符合静态猝灭规律。共振光散射强度的增加可能与埃洛石纳米管-溶菌酶复合物的形成而导致的分子尺寸的增加有关,这与紫外-可见吸收光谱的变化和静态猝灭机理相一致。同步荧光光谱分析表明两者之间的相互作用可能发生在色氨酸所处位置附近,作用过程使溶菌酶的二级结构发生变化,分子链错误折叠,加入浓度为100mg/L和200mg/L的埃洛石纳米管时,通过圆二色谱数据计算出分别导致α-螺旋的含量降低3.28%和6.89%。     

C@CdS/埃洛石纳米管复合光催化剂一步热解法的制备及光降解性能

通过一步热解法合成了一种新的复合光催化剂C@CdS/埃洛石纳米管(HNTs). 用扫描电镜(SEM),X射线能谱(EDS),透射电镜(TEM),X 射线衍射(XRD),紫外-可见漫反射光谱(UV-Vis DRS),傅里叶变换红外(FT-IR)光谱,比表面积和拉曼光谱(RS)对材料进行表征. 利用可见光下降解四环素探究了C@CdS/HNTs 的光催化活性. 结果表明,所制备的不同热解温度的样品中,400 ℃热解温度下的样品降解四环素效果最好,可见光照射60 min 降解率能达到86%. 此外,得益于碳层、CdS和HNTs 的共同作用,光催化剂展示了很好的稳定性. 放置一年对催化活性没有任何影响,并且经过三次循环实验,光催化剂活性没有很大变化. 最后讨论了光催化剂的制备机理,并且对光催化降解过程的中间产物进行了分析.     

C@CdS/埃洛石纳米管复合光催化剂一步热解法的制备及光降解性能(英文)

通过一步热解法合成了一种新的复合光催化剂C@CdS/埃洛石纳米管(HNTs).用扫描电镜(SEM),X射线能谱(EDS),透射电镜(TEM),X射线衍射(XRD),紫外-可见漫反射光谱(UV-Vis DRS),傅里叶变换红外(FT-IR)光谱,比表面积和拉曼光谱(RS)对材料进行表征.利用可见光下降解四环素探究了C@CdS/HNTs的光催化活性.结果表明,所制备的不同热解温度的样品中,400°C热解温度下的样品降解四环素效果最好,可见光照射60 min降解率能达到86%.此外,得益于碳层、CdS和HNTs的共同作用,光催化剂展示了很好的稳定性.放置一年对催化活性没有任何影响,并且经过三次循环实验,光催化剂活性没有很大变化.最后讨论了光催化剂的制备机理,并且对光催化降解过程的中间产物进行了分析.     

牛磺酸改性埃洛石纳米管的制备及其对四环素的吸附性能

四环素在环境中难于降解,容易残留在环境中,影响生态系统和人体健康。埃洛石纳米管是一种天然硅酸盐矿物,具有均匀的纳米中空管状结构。本文通过化学键合以牛磺酸对埃洛石纳米管表面进行修饰得到改性的埃洛石纳米管(HNTs-Tau),显著提高其对四环素的吸附能力。系统研究pH、吸附时间、吸附温度及离子强度对吸附性能的影响。结果表明,HNTs-Tau在pH=6的弱酸性溶液下吸附效果最佳。振荡时间为2 min时,去除率可达到90%以上。在25℃下采用10 mg HNTs-Tau对800μg/mL的四环素溶液的吸附容量可以达到512.5 mg/g。采用4种动力学模型拟合,HNTs-Tau对四环素的吸附行为更加符合准二级动力学模型。采用2种热力学模型拟合,HNTs-Tau对四环素的吸附行为更加符合Freundlich模型,对四环素的最大吸附容量可以达到714.3 mg/g。     

聚环氧乙烷的双层片晶

聚环氧乙烷(M_n=7000)的双层片晶形态用透射电镜和差示扫描量热计进行了研究。在结晶温区54—56℃,现察到双层片晶,高于这个温区,同时看到双层片晶及单层片晶,低于这个温区,只看到单层片晶。双层片晶的熔点稍高于单层片晶。根据非整数次折迭链晶向整数次折迭链晶的转变,讨论了双层片晶和单层片晶的生长过程。在双层片晶界面上的H键降低了表面自由能,这是形成双层片晶的主要原因。     

多孔二氧化硅对聚环氧乙烷结晶行为的影响

高分子化合物由于具有很长的分子链,不易进行规整排列,结晶速度通常很慢,为提高结晶速度,有时需要加入成核剂．多孔二氧化硅（ＳｉＯ２）具有较大的比表面积,故吸附作用较强,有可能作为成核剂影响部分结晶高聚物的结晶过程．聚环氧乙烷（ＰＥＯ）为部分结晶高聚物,其结晶行为对杂质较为敏感．本文目的在于通过结晶动力学及结晶与熔融行为的研究,探索多孔二氧化硅对ＰＥＯ结晶行为的影响．１　实验部分　　聚环氧乙烷（ＰＥＯ,Ｍｗ＝１×１０５）．两种多孔二氧化硅（ＳｉＯ２）按文献［１］方法制备,平均粒度为０．３μｍ,平均孔…     

醚链改性聚环氧乙烷的合成及性能研究

考察烷基磷酸铝催化剂i-Bu₃Al/H₃PO₄/DBU催化环氧乙烷(EO)、甘醇甲基缩水甘油醚(nGE)与烯丙基缩水甘油醚(AGE)二元及三元共聚合的催化性能,通过核磁共振波谱(NMR)、凝胶渗透色谱(GPC)和示差扫描量热仪(DSC)对共聚物微观结构和热性能进行表征分析。结果表明25℃甲苯溶剂中,i-Bu₃Al/H₃PO₄/DBU催化剂可以高效催化不同比例的EO、nGE和AGE共聚合,以100%收率获得组成精确可控的高分子量EO-nGE二元及EO-AGE-nGE三元无规共聚物;nGE的醚链长度对聚合性能无影响,二甘醇甲基缩水甘油醚(2GE)和四甘醇甲基缩水甘油醚(4GE)均可实现可控引入聚环氧乙烷制备醚链改性聚环氧乙烷。EO-AGE-nGE三元共聚物以1,2-乙二硫醇为交联剂制备了交联聚合物。测试醚链改性聚环氧乙烷的性能,发现醚链长度、含量及交联对聚合物电导率和力学性能有很大影响。4GE为共聚单体的聚环氧乙烷电导率高于2GE。随着醚链含量增大,聚合物电导...     

聚环氧乙烷/聚乙基■唑啉共混体系结晶行为及相容性的研究

用偏光显微镜（ＰＬＭ）、ＤＳＣ、ＩＲ和ＷＡＸＤ等测试方法对聚环氧乙烷（ＰＥＯ）／聚乙基唑啉（ＰＥＯｘ）共混体系结晶行为及相容性进行了研究．结果表明，ＰＥＯ含量在３０％以上的共混体系中，几乎完全被球晶充满，非晶态ＰＥＯｘ作为微区分散在大球晶之间或之中；含量为２０％的共混体系照片上呈树枝状晶；含量低于１０％时则看不到结晶出现，体系形成单一的非晶相．对任何组成的共混物，均只出现单一的玻璃化转变温度（Ｔｇ），而且符合Ｆｏｘ方程揭示的规律；随ＰＥＯｘ组分含量的增加，共混体系的结晶度减小，熔点下降，并利用平衡熔点方程计算出ＰＥＯ与ＰＥＯｘ的相互作用能密度．非晶ＰＥＯ与ＰＥＯｘ热力学相容，其相容性是由于这两种分子间存在着特殊相互作用．ＰＥＯｘ的加入不会改变ＰＥＯ的晶胞参数．     

Confinement Effects on the Crystallization of Poly(ethylene oxide) Nanotubes

In this work, we show the effects of nanoconfinement on the crystallization of poly(ethylene oxide) (PEO) nanotubes embedded in anodized aluminum oxide (AAO) templates. The morphological characteristics of the hollow 1D PEO nanostructures were evaluated by scanning electron microscopy (SEM). The crystallization of the PEO nanostructures and bulk was studied with differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The crystallization of PEO nanotubes studied by DSC is strongly influenced by the confinement showing a strong reduction in the crystallization temperature of the polymer. X-ray diffraction (XRD) experiments confirmed the isothermal crystallization results obtained by DSC, and studies carried out at low temperatures showed the absence of crystallites oriented with the extended chains perpendicular to the pore wall within the PEO nanotubes, which has been shown to be the typical crystal orientation for one-dimensional polymer nanostructures. In contrast, only planes oriented 33, 45, and 90° with respect to the plane (120) are arranged parallel to the pore's main axis, indicating preferential crystal growth in the direction of the radial component. Calculations based on classical nucleation theory suggest that heterogeneous nucleation prevails in the bulk PEO whereas for the PEO nanotubes a surface nucleation mechanism is more consistent with the obtained results.     

Effects of Inorganic Salts on Micellization and Solubilization in an Aqueous Solution of Poly(ethylene oxide)/Poly(propylene oxide)/Poly(ethylene oxide) Triblock Copolymer

The effects of inorganic salts on micellization and solubilization of prednisolone in aqueous solution of poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymer (Pluronic P85) were studied. The effect of inorganic salts on decrease in the cloud point and the critical micelle concentration (cmc) of Pluronic P85 was the order of Na₂HPO₄ > NaH₂PO₄ > NaCl > NaBr. Moreover, it was found that Pluronic P85 forms two kinds of micelles: monomolecular micelles and polymolecular micelles. The polymolecular micelle increased with increasing amount of added inorganic salts. Moreover, solubilization behavior is explained from the standpoint of salting out for prednisolone and association characteristics of Pluronic P85.     

Electrostatic Assembly of Poly(ethylene glycol) Nanotubes

Poly(ethylene glycol) (PEG)‐based films, nanotubes, and nanotube arrays were successfully made using layer‐by‐layer (LbL) assembly ion‐containing PEO derivatives on porous templates and planar substrates. PEG nanotubes are challenging to produce because PEG dissolves into solutions and solvents used during nanotube processing, but our techniques circumvent the issue. Nanotube dimensions were verified using microscopy and the average observed diameter was 155 nm. The PEG‐based structures showed remarkable stability in water, salt water, and sodium hydroxide solution.

     

新型磷-氮有机金属阻燃剂的合成及其热稳定性

以γ-氨丙基三乙氧基硅烷(1)和二苯基氯化膦(2)为原料,经取代反应制得N-(二苯基膦基)-1,1-二苯基-N-［3-(三乙氧基甲硅烷)丙基］膦氮配体(3); 3与六水合氯化镍(4)反应合成了一种新型的磷-氮有机金属阻燃剂(5),其结构经¹H NMR, ³¹P NMR和FT-IR表征。研究了物料比［r=n(2) : n(1)］、溶剂、反应时间和反应温度对3收率的影响。结果表明：在最佳反应条件［二氯甲烷为溶剂,1 19 mmol, r=2.3,于25 ℃反应14 h］下,3收率89.5%。 TGA测试结果表明：5的初始分解温度为252 ℃, 700 ℃残炭为31.9%。     

PMMA对聚氧乙烯β转变的影响

对半结晶聚氧乙烯（PEO)/PMMA共混体系的DSC及动态力学行为研究表明：PEO在和PMMA形成半结晶PEO/PMMA共混体系后，其β转变的峰温没有明显移动；β峰只出现在淬炎的半结晶PEO/PMMA共混体系中，而在完全非晶的相容性共混体系以及退火的半结晶共混体系不出现；在β转变区，对应的模量反常地增大，对应的DSC曲线有明显阶跃。可见，半结晶PEO的β转变并不象通常所认为的源于PEO非晶区的玻璃化转变。在接受半结晶PEO及半结晶PEO/PMMA共混体系的PEO结晶区存在结晶-非晶中间相观点的基础上，认为β转变源于PEO结晶区结晶-非晶中间相的玻璃化转变过程。     

Effect of Phosphorus-Nitrogen Intumescent Flame Retardant on Structure and Properties of Poly(propylene)

Summary : Phosphorus-nitrogen intumescent product (R₂₀₀₀) was filled into polypropylene (PP) as a flame retardant. The neat PP and flame-retarded PP blends were studied for their structural and mechanical properties after verification of the flame retardancy character of blends. In this paper, the influence of incorporation of different amount (5%, 10%, 15%, 20%, and 25%) of R₂₀₀₀ was studied. The flame retardancy is evaluated by limiting oxygen index (LOI) value, which is enhanced from 17.5 for pure PP to 22.7 for the blend comprising 15% intumescent product, phosphorus-nitrogen based (R₂₀₀₀). The thermal degradation behaviour of the PP/R₂₀₀₀ blends was investigated using thermogravimetric analysis (TGA) under nitrogen (N₂) and oxygen (O₂) atmospheres. The influence of the R₂₀₀₀ on the PP crystallization was examined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Further, the mechanical properties of the materials were studied by dynamic mechanical analysis (DMA). The incorporation of the flame retardant had no effect on the crystallization of the neat polymer and the mechanical properties of the materials remained unaffected.     

Compatibility of Poly(vinyl chloride) with Polyalkyleneoxides. I. Poly(methylene oxide) and Poly(ethylene oxide)

The compatibility of poly(vinyl chloride) (PVC) with linear polyethers is examined over the entire composition range. This study examines blends with poly(methylene oxide) (PMO) and poly(ethylene oxide) (PEO) of medium (MMW) and high (HMW) molecular weight. The techniques used are dynamic mechanical analysis, DSC, and optical microscopy (phase contrast and polarizing). The results indicate that all polyethers show limited miscibility in the melt at high PVC contents. Proper analysis of the T_m data using the Kwei-Frisch and Hoffman-Weeks procedures allows the determination of the thermodynamic interaction parameter, which is found to be close to zero for all pairs of blends.     

Synthesis of Poly(ethylene oxide) Approaching Monodispersity

Polydispersity in polymers hinders fundamental understanding of their structure–property relationships and prevents them from being used in fields like medicine, where polydispersity affects biological activity. The polydispersity of relatively short‐chain poly(ethylene oxide) [(CH₂CH₂O₂)_n; PEO] affects its biological activity, for example, the toxicity and efficacy of PEOylated drugs. As a result, there have been intensive efforts to reduce the dispersity as much as possible (truly monodispersed materials are not possible). Here we report a synthetic procedure that leads to an unprecedented low level of dispersity. We also show for the first time that it is possible to discriminate between PEOs differing in only 1 ethylene oxide (EO) unit, essential in order to verify the exceptionally low levels of dispersity achieved here. It is anticipated that the synthesis of poly(ethylene oxide) approaching monodispersity will be of value in many fields where the applications are sensitive to the distribution of molar mass.