聚乙烯亚胺为主链的液晶高分子研究进展

综述了近几年以聚乙烯亚胺(PEI)为主链的液晶高分子的研究进展.从PEI型液晶高分子的原理、结构和性能方面着手,展望了几类新型PEI液晶高分子的发展趋势.     

HECS-g-PDLLA共聚物的微波合成及与聚乳酸的相容性

在微波作用下,以辛酸亚锡为催化剂,羟乙基壳聚糖（HECS）为大分子引发剂引发D,L-丙交酯（D,L-LA）开环聚合制备羟乙基壳聚糖-g-聚乳酸（HECS-g-PDLLA）,通过红外（IR）、元素分析（EA）、氢核磁共振（1H-NMR）、X射线衍射（XRD）和差示扫描量热分析（DSC）对产物进行了表征。然后采用溶液共混法...     

压电聚偏氟乙烯纳米纤维的应用进展

压电聚合物因柔性、加工容易和成本低等优点备受人们的关注,尤其是在生物医学、能源和电子信息等领域的数据储存器、纳米发电机、传感器和驱动器等器件的开发方面有十分广泛的应用。文中对聚偏氟乙烯的结晶结构、晶型调控以及应用方面进行综述,重点介绍聚偏氟乙烯压电聚合物纳米纤维材料的结构调控及在纳米器件等应用方面的最新研究进展。     

再生胺吸附解吸脱硫工艺与其它典型脱硫方式的简单比较

简要介绍了再生胺吸附解吸脱硫工艺的原理、特点、优势、发展前景,以及在实际运行中暴露出来的问题.并与现行已有的其他典型脱硫方式进行简单比较.     

聚离子液体的合成及其在吸附分离领域中的应用 研究进展

聚离子液体(PILs)能结合离子液体与聚合物的优点,兼具优异的机械稳定性、加工性、离子导电性和化学相容性等,近年来受到学术界的广泛关注.介绍了聚离子液体的分类及合成方法,综述了聚离子液体在吸附分离领域的应用,并对聚离子液体的发展进行了展望.未来有关聚离子液体的研究中,化学结构与性能之间的构效关系、新型聚离子液体的合成及其应用将是聚离子液体的重要发展方向.     

Influence of Surface-functionalized Graphene Oxide on the Cell Morphology of Poly(methyl methacrylate) Composite

The surface chemistry of filler is closely related to the structure and morphology of nanocomposite foams.Changing the property of filler is widely used to control the cell structures and functionalize the composite foams.Surface-functionalized graphene oxide(GO-ODA) was prepared by grafting octadecylamine(ODA) on the surface of graphene oxide(GO) to make the filler disperse better in the nanocomposites and have a strong interfacial interaction with polymer matrix.Poly(methyl methacrylate)(PMMA)/GO-ODA nanocomposite foams were obtained by solution blending and foamed using supercritical carbon dioxide(scCO_2).Compared to neat PMMA and PMMA/GO samples,the PMMA/GO-ODA nanocomposite foams showed improved cell structures with smaller size,higher cell density and more homogeneous distribution,which should be attributed to the heterogeneous nucleation caused by well-dispersed GO-ODA nanosheets.This work not only improved the compatibility and interfacial interaction of GO with polymer matrix but also indicated that the modified GO sheets can act as ideal filler to control the cell density,size and size distribution efficiently.     

聚(N-异丙基丙烯酰胺)-b-聚苯乙烯改性玻璃表面对细胞黏附/脱附的调控

通过表面引发连续原子转移自由基聚合的方法在玻璃表面接枝了聚(N-异丙基丙烯酰胺)-b聚苯乙烯(PNIPAAm-b-PS)双嵌段聚合物刷.测试结果表明改性表面具有一定的浸润性温度响应性以及良好的生物学性能.与未改性的玻璃表面相比,改性后的表面具有良好的排斥血浆蛋白质的非特异性吸附能力.此外,PS链段的引入在不影响表面温敏性调控细胞黏附/脱附的务件下能够有效提高PNIPAAm改性表面在温度高于其低临界溶解温度(LCST)时对细胞的黏附能力.     

聚乙烯醇水溶液低温稳定性的影响因素

通过测定聚乙烯醇水溶液表观黏度随时间的变化,并结合结构分析,研究了低温(10℃)环境中聚乙烯醇聚合度、醇解度及质量分数对聚乙烯醇水溶液稳定性的影响。结果表明,当醇解度、质量分数一定时,聚合度越大,聚乙烯醇水溶液越容易发生凝胶;当聚合度、质量分数一定时,醇解度越大,聚乙烯醇水溶液的稳定性越差;当聚合度、醇解度一定时,质量分数越大,聚乙烯醇水溶液发生凝胶的时间越短。在此基础上,确定了醇解度99%的PVA水溶液发生凝胶的临界质量分数和凝胶化时间。     

一种可促进成骨细胞黏附和生长的聚乙二醇接枝聚乳酸材料

用氨基封端聚乙二醇(H2N-PEGNH2)对聚乳酸(PLA)进行了本体改性,通过FITC荧光标记牛血清白蛋白(FITC-BSA)对材料的抗非特异性蛋白吸附性能进行了检测,在材料上体外培养Wistar大鼠成骨细胞,检测了材料的细胞相容性.结果表明:与聚乳酸相比,得到的产物聚乙二醇改性聚乳酸(PPLA)明显降低了对牛血清白蛋白的非特异性吸附,仅为PLA的37.3%,显著促进了成骨细胞的黏附和生长.由于该材料具有良好的亲水性、可降解性、细胞相容性及可反应性,预计在组织工程和药物缓释中有潜在应用.     

Electrochemical Characteristics of LaNi_(4.5)Al_(0.5) Alloy Used as Anodic Catalyst in a Direct Borohydride Fuel Cell

Fuel cells using borohydride as the fuel have received much attention because of high energy density and theoretical working potential.In this work,LaNi4.5Al0.5 hydrogen storage alloy used as the anodic material has been investigated.It was found that the increasing operation temperature was helpful to the open-circuit potential,the discharge potential and the power density,but showed a negative effect on the utilization of the fuel due to the accelerated hydrogen evolution.The high KOH concentration was favorable for high-rate discharge capability.The adsorption and transformation of hydrogen on LaNi4.5Al0.5 alloy electrode has been observed,but its contribution to the discharge capability during a high-rate discharge was small.     

Compatibility of poly(α-methyl styrene-co-acrylonitrile) with PMMA: A neutron and cloud point study

Cloud point (CP) experiments were perform-ed using blends of deuterated polymethylmethacrylate (PMMA(D)) and a statistical copolymer P(αMS – co- AN) which consists of α-methylstyrene (αMS) and acrylonitrile (AN). A lower critical solution temperature (LCST) behavior is found. The corresponding interaction parameter χ is calculated accounting for temperature and concentration dependence. In order to improve the accuracy, temperature dependent small-angle neutron scattering experiments are performed for a 50/50 blend which reveal spinodal and binodal temperatures. Additionally, bilayers of P(αMS – co- AN) and PMMA(D) are prepared and annealed. The compositions of coexisting phases and the interface widths are determined by neutron reflectometry (NR). Interaction parameters calculated from the compositions of coexisting phases are in agreement with SANS and CP results. Effects of molar mass distribution are discussed. Received: 17 October 2000 / Reviewed and accepted: 18 October 2000     

聚氨基酸共聚物合成研究进展

聚氨基酸共聚物是一类新型生物降解高分子材料。文中简单综述了聚氨基酸-聚醚嵌段共聚物、聚氨基酸-甲壳素共聚物、聚氨基酸-硅氧烷共聚物和聚氨基酸-聚酯共聚物的合成方法。     

聚对苯二甲酸乙二醇酯的结晶成核改性研究进展

聚对苯二甲酸乙二醇酯(PET)因其重复结构单元中含有刚性苯环而成核慢、结晶度低,从而导致综合力学性能与耐热性较差,限制了其工程化应用,故对PET进行成核改性以提高结晶速率与结晶度成为亟待解决的问题。综述了PET的4大类成核剂:无机填料、有机小分子、有机高分子及复合型成核剂;在此基础上,提出机理上不同于异相成核的"离子簇集诱导成核"的概念,即与离子共价相连的聚合物链段因离子簇集而在离子簇近围紧密堆砌,从而诱导"拥挤"链段结晶成核。无机填料类成核剂包括粘土、氧化物与氢氧化物、无机盐、Si_3N_4及碳纳米管/石墨等,其成核机理均为异相成核。有机小分子类成核剂涉及羧酸盐、二胺、双酰胺及改性山梨醇等,其中羧酸盐成核机理为离子簇集诱导成核,而其它均属于异相成核。有机高分子类成核剂分为结晶性聚合物、液晶高分子、嵌段共聚物及离子交联型聚合物等;其中前三者属异相成核,后者为离子簇集诱导成核。复合型成核剂为两种以上成核剂(或成核机理)配合使用协同促进PET结晶成核。对比发现,有机高分子与复合型成核剂效果较好,且不会引起PET的降解,为PET优良成核剂。异相与离子簇集诱导耦合高分子成核剂为PET结晶成核改性未来的重点发展方向之一。     

以二异氰酸酯为增容剂的聚甲基乙撑碳酸酯/聚乳酸共混材料的制备与性能

在聚甲基乙撑碳酸酯(PPC)/聚乳酸(PLA)共混体系中加入2,4-甲苯二异氰酸酯(TDI)作为增容剂,通过熔融共混的方法使TDI与PFC及PLA的端羟基反应形成扩链产物,制备了一系列共混物.共混物的DSC曲线及扫描电镜图表明,形成的扩链产物使该二元共混体系相容性得到明显改善,共混材料的力学性能和热性能都得到显著提高....     

A Quantitative Method for Determination of Lactide Composition in Poly(lactide) Using (1)H NMR

A method has been developed to quantitatively determine the composition of d-lactide and meso-lactide stereoisomer impurities in poly(lactide) containing predominantly l-lactide. In this method, the stereosequence information obtained from a few well-resolved resonances in the (1)H NMR spectrum representing RR and R stereogenic defects is used. The d-lactide and meso-lactide as minor components lead to RR and R stereogenic defects, respectively, which influence the isotactic chain length distribution and hence affect the polymer properties. Analytical equations relating the stereosequence probability to the lactide feed composition are not available due the complicated kinetics involved for the melt polymerization; viz. the preference for syndiotactic lactide addition decreases with reducing residual lactide concentration in the batch process. Hence, empirical correlations were determined by least-squares fit to the predictions for the specific stereosequence probabilities provided by Monte Carlo calculations of a number of lactide stereocopolymerizations. The Monte Carlo calculations simulate the kinetics observed for melt polymerization at 180 °C catalyzed by Sn(II) bis(2-ethylhexanoate) (Sn(II) octoate) in a 1:10 000 catalyst/lactide ratio.     

聚异丙基丙烯酰胺在生物医学领域中的研究进展

聚异丙基丙烯酰胺是一类具有温度敏感性的智能高分子材料,其特性在生物医学领域加以利用,可基本满足生物医学用材料的要求,具有广阔的应用前景.从聚合物角度综述了聚异丙基丙烯酰胺近几年在组织工程、药物释放体系、生物分离等领域的研究进展.     

聚碳酸亚丙酯共混改性研究进展

聚碳酸亚丙酯(PPC)是一种新型脂肪族聚碳酸酯,具有良好的生物相容性、降解性和极低的氧透过率,但其热性能和机械强度较差。聚碳酸亚丙酯的共混改性可以有效改善其性能。综述了近年来国内外聚碳酸亚丙酯共混改性的研究情况,分别介绍了聚碳酸亚丙酯/合成聚合物、聚碳酸亚丙酯/天然聚合物、聚碳酸亚丙酯/无机粒子、聚碳酸亚丙酯/有机小分子复合材料的制备方法与性能,并展望了其发展前景。     

Control of the in vivo Biodistribution of Hybrid Nanoparticles with Different Poly(ethylene glycol) Coatings

Fluorescent nanoparticles containing a gadolinium oxide core are very attractive because they are able to combine both imaging (fluorescence imaging, magnetic resonance imaging) and therapy (X‐ray therapy and neutron‐capture therapy) techniques. The exploitation of these multifunctional particles for in vivo applications requires accurate control of their biodistribution. The postfunctionalization of these particles by four different poly(ethylene glycol) derivatives, which differ by chain length and end group, exerts a great influence on the ζ potential of the nanoparticles and on their biodistribution after intravenous injection to HEK‐β3‐tumor‐bearing mice. This study reveals that the behavior of PEGylated nanoparticles, which was monitored by in vivo fluorescence imaging, depends on both the chain length and the end group of the PEG chain.