MWCNTs/hydroxypropyl cellulose/polyethylene glycol-based shape-stabilized phase change materials

Journal of Thermal Analysis and Calorimetry - Polyethylene glycol (PEG) is widely used as phase change materials (PCMs). However, the leakage and low thermal conductivity issues restrict its...     

Determination of the thermodynamic polymer-polymer interaction parameter of miscible blends prepared from two crystalline polymers

The melting points of miscible blends prepared from two crystalline polymers, poly(caprolactone) (PCL), and Saran a random copolymer of vinylidene chloride with vinyl chloride [P(VCl₂-VC)], vinyl acetate [P(VCl₂-VA)], or acrylonitrile [P(VCl₂-AN)], have been measured by differential scanning calorimetry as a function of the crystallization temperature. The equilibrium melting points of these blends have been determined by Hoffman-Weeks plots. From two series of data, one of which was obtained by measuring the melting points of PCL crystals and the other by measuring the melting points of Saran crystals, the thermodynamic polymer-polymer interaction parameters of PCL/Saran blends have been calculated over the full range of composition. The two series of data merge into a smooth curve, which is composition dependent, despite the fact that the melting points of PCL and P(VCl₂-VC) or P(VCl₂-VA) are very different at 58.1, 183.5, and 184.2°C, respectively. Calculations using the “equation of state” Prigogine-Flory thermodynamic theory indicate that the temperature dependence of the thermodynamic interaction parameter in typical polymer blends is small, which agrees with the experimental results.     

原位缩聚制备聚氨酯/碳纳米管复合泡沫材料

采用球磨方法制备了均匀分散的碳纳米管(CNTs)/聚丙二醇分散体系,解决了碳纳米管在高黏滞聚醚醇中的分散问题,进一步以水为发泡剂,采用两步的原位缩聚法制备了碳纳米管均匀分散的聚氨酯(PU)/碳纳米管复合泡沫材料.通过FTIR、SEM、压缩实验、亲水性实验等表征了材料的结构和性能.结果表明碳纳米管的加入使聚氨酯材料的压缩强度和保水率得到显著提高.     

硫代氨基甲酸酯合成方法进展

硫代氨基甲酸酯是一类分子内含有多种官能团的化合物,大多数具有生物活性,在医学、生物、农药等方面有广泛的应用.本文总结了合成硫代氨基甲酸酯的几种主要方法,如水解醇解法、重排反应、光气衍生物法、羰基化法等,并分析了各种方法的利弊.指出利用一氧化碳进行硒催化的硫醇与硝基化合物或苯胺的羰基化反应来合成硫代氨基甲酸酯是一种比较有应用前景的方法.该方法具有环境友好、原子经济性高、步骤简短等优点,并对其做了比较详细的介绍.     

一种新型贝壳基质蛋白的重组表达与功能分析

贝壳是在贝壳基质蛋白的调控下形成的生物矿化产物，也是生物工程和生物材料学研究的重要对象。贝壳基质蛋白通过调控碳酸钙晶体的成核和生长过程，使贝壳形成有规则的纳米结构并赋予贝壳极强的力学性能。在厚壳贻贝肌棱柱层中鉴定到一种新型贝壳基质蛋白，因其富含谷氨酰胺而被命名为富含谷氨酰胺的贝壳蛋白（Glutamine-rich shell protein，GRSP)，该蛋白序列中含18.2%的谷氨酰胺以及PDZ (Postsynaptic density/Discs large/Zonula occludens)和ZM (ZASP-like Motif)结构域。为了解GRSP在生物矿化过程中的分子机理，在序列分析的基础上，采用密码子优化结合原核重组表达策略，获得重组厚壳贻贝GRSP；进一步利用扫描电镜和傅里叶红外光谱，分析重组GRSP对方解石型以及文石型碳酸钙晶体在形貌和晶型方面的影响；同时，利用沉淀法分析重组GRSP对碳酸钙结晶速度的影响以及与碳酸钙晶体的结合作用。结果表明，重组GRSP可诱导文石型碳酸钙晶体发生形貌变化，并对方解石型碳酸钙晶型产生影响。此外，重组GRSP表现出与碳酸钙结合的活性并能抑制方解石型碳酸钙晶体的结晶速度。上述结果表明，GRSP蛋白可能对贝壳的形成及发育具有重要影响并在贝壳肌棱柱层的形成中发挥重要作用。     

水溶性含糖共轭聚合物的制备及应用

水溶性共轭聚合物具有优异的光学稳定性、高亮度、易于修饰和水溶性等特点,广泛应用于离子检测、蛋白检测和生物成像等领域。水溶性共轭聚合物主要通过在共轭聚合物的侧基或端基修饰水溶性的离子基团或水溶性聚合物实现其水溶性,水溶性共轭聚合物还可以通过引入功能性基团或聚合物使其具备不同的功能特性。糖化合物是天然存在的一类生物分子且大部分具有水溶性的特点,因此最近十几年来科研工作者将糖化合物引入共轭聚合物中以赋予共轭聚合物糖化合物的生物功能特性。本文总结了水溶性含糖共轭聚合物的制备方法、化学结构及其在凝集素、细菌检测和细胞荧光成像中的应用。最后总结了此类聚合物的特性、发展方向及目前所需解决的问题。     

Self-assembly and confinement behaviors of poly(ethylene glycol) distearate within lamellar-mesostructured silica

Novel lamellar-mesostructured poly(ethylene glycol) distearate (PEGDS)/silica hybrids have been synthesized successfully through self-assembly with a sol–gel technology, in which the PEGDS is imbedded within silica interlayers through a micelle-templating technique by seeding rod micelles of the PEGDS as surfactant aggregate during the condensation of the silica sol performed by the hydrolysis of organosilane precursor. The well-ordered lamellar mesostructure was confirmed by X-ray diffraction patterns, transmission electronic microscopy, and N₂ adsorption–desorption isotherms. Studies on confined behaviors of the PEGDS within silica matrix indicated that the molecular chains of the PEGDS with two-dimensional degree of freedom could still crystallize, though they were stranded one-dimensionally between the silica interlayers. However, the confinement effects of the lamellar mesostructure caused a significant decrease in both the melting and crystallization temperatures of the PEGDS.     

Density-Dependent Emission Colors from a Conformation-Switching Chromophore in Polyurethanes

Achieving full-color emission from a single chromophore is not only highly desirable from practical considerations, but also greatly challenging for fundamental research. Herein, we demonstrated the density-dependent emission colors from a single boron-containing chromophore, from which multi-color fluorescent polyurethanes were prepared as well. Originating from its switchable molecular conformations, the emission color of the chromophore was found to be governed by the packing density and strongly influenced by hydrogen bonding interactions. The chromophore was incorporated into polyurethanes to achieve full-color emitting materials; the emission color was only dependent on the chromophore density and could be tuned via synthetic approach by controlling the compositions. The emission colors could also be modulated by physical approaches, including by swelling/deswelling process, compression under high pressure, and even blending the fluorescent polyurethane with non-emitting ones.     

Selenium-Catalyzed Oxidative Carbonylation of Aniline and Alcohols to N-Phenylcarbamates

A facile one-pot, phosgene-free synthesis of N-phenylcarbamates is demonstrated. Catalyzed by selenium, oxidative carbonylation of aniline with alcohols in the presence of carbon monoxide and oxygen affords the corresponding N-phenylcarbamates, mostly in fair to good yields. Selenium can be easily recovered because of its phase-transfer catalysis function.     

Preparation and thermal properties of fatty acids/CNTs composite as shape-stabilized phase change materials

A series of fatty acids/carbon nanotubes (CNTs) composite shape-stabilized PCMs were prepared through infiltration method by using the eutectic mixture of capric acid, lauric acid, and palmitic acid as phase change materials, multi-walled CNTs as a supporting material. Nitrogen adsorption–desorption curves and SEM images of composite shape-stabilized PCMs indicate that the eutectic mixture was effectively absorbed into the porous structure of the CNTs. DSC thermograms show that the composite fatty acids/CNTs possess good phase change behavior. And the latent heat of the sample absorbed with 80 wt% fatty acids can achieve 101.6 J g^?1 in the melting process and its phase change temperatures and latent heat almost remain unchanged in 30 times of thermal cycling. Moreover, the thermal conductivity of the composite materials are significantly improved (up to 0.6661 W m^?1 k^?1) due to the addition of the highly thermal conductive CNTs.