聚电解质的制备与应用研究进展

文中综述了聚电解质的合成及应用研究进展,探讨了聚电解质制备过程中的影响因素。此外还着重介绍了聚电解质-表面活性剂复合物、层层自组装膜、聚电解质微纳胶囊在药物缓释以及聚电解质在改善纳米材料的制备及性能方面上的应用研究进展。如何开发特定结构的聚电解质,利用聚电解质对外界环境的刺激实现对聚电解质形态结构的实时和有效控制是聚电解质科研领域研究的重点方向。     

采用层层组装技术制备TiO2中空纳米纤维膜催化剂

采用静电纺丝技术和层层组装技术制备了聚电解质/TiO2复合中空纳米纤维.以电纺聚苯乙烯纤维为模板,聚电解质交替吸附在纤维表面,再用有机溶剂溶掉PS纤维模板获得多层聚电解质中空纤维.纤维的平均直径和壁厚能通过模板和吸附层数很好的得到控制.在对比P25 TiO2和TiO2中空纤维对亚甲基蓝的光催化性能实验中,发现TiO2中空纤维具有更好的光催化性能.TiO2/聚电解质复合中空纳米纤维有望应用于光催化,可控药物释放等.     

静电自组装膜研究进展

由静电自组装技术来制备功能型薄膜是发展迅速的新研究领域。本文着重阐述了静电自组装聚电解质-聚电解质复合膜、静电自组装聚电解质-无机纳米粒子复合膜、静电自组装聚合物-半导体纳米粒子复合膜、静电自组装其他多层膜体系制备方法和特点,展望了静电自组装在渗透分离膜、基因传输、传感器系统、光伏设备等领域的应用前景。     

磁性纳米球形聚电解质刷的制备研究

聚电解质刷因与生物大分子具有良好的相容性而备受关注。以苯乙烯单体(ST)为原料,采用细乳液聚合法制备包覆有Fe_3O_4的聚苯乙烯纳米磁核粒子(MPS),以安息香丙烯酸酯(BA)为光引发剂,丙烯酸(AA)为聚电解质刷链原料,制备了链长可控的磁性纳米球形聚电解质刷(MSPB)。考察BA、AA和聚合反应时间对合成聚电解质刷链长的影响,优化MSPB的制备工艺条件,并采用动态光散射、热重和扫描电镜等手段对MSPB的结构和性能进行表征。结果表明:制备MSPB的最优工艺条件为:当ST为2.5g,BA/ST=0.1(摩尔比,下同),AA/ST=0.9,聚合反应时间2.0h时,未接枝MPS平均粒径为152nm,聚电解质刷链长约为160nm,并具有超顺磁性。将MSPB用于中性蛋白酶固定化,固定化酶含量为42.9mg/g载体,固定化酶比活为1.75×104u/g载体,酶活回收率达93%,表明MSPB可为固定化酶提供一种良好的载体。     

磁性石墨烯的制备初探

目的制备磁性石墨烯,实现其定向排列,为进一步制备性能良好的热界面材料提供定向导热相。方法采用聚合物包覆和层层组装技术,在石墨烯表面均匀包覆带负电荷的聚磺苯乙烯(PSS)聚电解质层,然后在静电力作用下包覆一层带正电荷的聚二烯丙基二甲基氯化铵(PDDA)聚电解质。最后,借助静电力使带负电荷的磁性Fe3O4纳米粒子在附着有PDDA层的石墨烯表面形成均匀的致密覆盖层,得到磁性石墨烯,并在外磁场作用下使磁性石墨烯进行定向排列。结果采用聚电解质层层组装技术可有效地对石墨烯进行磁性化处理;粉状石墨烯比片状石墨烯定向排列效果明显;以片状石墨烯为原材料的实验条件下,加入聚电解PSS、PDDA的量越多,磁性化效果更佳。结论通过聚电解质层层组装技术可有效地对石墨烯进行磁性化处理,并在磁场作用下实现定向排列。     

双重致孔制备中空胶囊

高分子大胶囊在医疗、化工、环境、能源等领域都有着广泛的应用,目前的制备方法多是单纯的物理或化学方法,对胶囊的孔隙率,尺寸大小等结构的控制也较为困难。以N,N二甲基甲酰胺为溶剂,聚偏氟乙烯为成囊高分子,硼氢化钠为发泡剂,水为凝固浴,在相分离和硼氢化钠发泡的双重致孔作用下制备出了具有大囊腔高孔隙率的中空胶囊。同时,还研究了硼氢化钠的浓度、温度等因素对胶囊结构的影响,并提出了分相-发泡理论,为制备不同尺寸和孔隙率的胶囊提供了理论依据,也为胶囊进一步的广泛应用提供了可能。     

纳米胶囊的制备与应用进展

扼要阐述了纳米胶囊的制备方法,包括乳液聚合法、凝聚相分离法、无机物化学镀膜法、聚电解质交替吸附法,以及界面溶剂交换技术、逐层纳米自组装技术、双乳液蒸发技术和超临界流体技术等新型制备技术。介绍并展望了纳米胶囊在生物医药、塑料及相变材料等领域的应用及发展趋势。     

Co2O3和MnCO3掺杂对低压ZnO压敏电阻电性能的影响

概述了低压ZnO压敏电阻的重要添加剂的作用,阐述了其电性能"三参数"(压敏电压梯度、非线性系数和漏电流)的影响因素.用低压ZnO压敏电阻的基本配方,以及在此基础上分别添加Co2O3、MnCO3、Co2O3 MnCO3四种配方制备样品作对比实验.发现Co2O3、MnCO3掺杂后都能引起压敏电压梯度升高,非线性系数显著提高,漏电流明显降低,且效果Co2O3 MnCO3大于MnCO3大于Co2O3.对造成上述差别的原因进行了深入分析.     

核壳结构MnCO3@Mn3O4球形颗粒的制备及其电化学性能研究

以硫酸锰为原料合成出球状MnCO3作为前驱体,加入KMnO4,通过化学沉淀法成功制备出粒径范围在0.5～1.0μm的核壳结构MnCO3@Mn3O4球形颗粒。通过对比实验发现,MnCO3、KMnO4和盐酸的添加量对最终产物的形成有很大的影响。电化学性能测试表明,核壳结构MnCO3@Mn3O4球形颗粒兼有双电层电容和赝电容特性,其最大比电容可以达到156F/g。     

银粒子修饰聚醚砜抗污染中空纤维膜的制备与性能研究

采用原位还原法制备的银粒子对聚醚砜中空纤维超滤膜进行修饰以提高膜的抗污染能力。以聚乙烯吡咯烷酮(PVP)为分散剂,乙二醇为还原剂,在聚醚砜溶液中将硝酸银还原成银粒子,同时采用相转化法制备中空纤维超滤膜。与未修饰的聚醚砜膜相比,经过银粒子修饰的聚醚砜中空纤维膜的抗污染能力和力学性能都得到明显提高,并且膜的初始水通量和截留率也高于未修饰的膜。当PVP含量为7.5%时,银粒子修饰的聚醚砜中空纤维膜的抗污染能力达到最强,膜的综合性能达到最佳:初始水通量为183L/(m2.h),截留率为94.5%,断裂强度为2.87MPa。在此条件下制备含银膜时,银的流失率仅为4.7%,每100g膜中银粒子的含量为4.55g。     

Hydrogen-bonding layer protecting polyelectrolyte capsules and its mechanical property study with atomic force microscope

The hydrogen-bonding multilayered polyelectrolyte capsules with sizes around 6 microm were fabricated by layer-by-layer self-assembly method. The morphology of the obtained capsules was observed with Scanning Electron Microscope (SEM), Confocal Laser Scanning Microscope (CLSM) and Atomic Force Microscope (AFM), respectively. The elastic properties of the capsules were studied with AFM. The capsule was pressed by cantilever with different lengths, a glass bead glued at the end of the cantilever. The force curves were measured on the capsule in air. The Young's modulus of the capsule was obtained (E = 170 MPa for the loading). Results show that this model can predict the elastic deformation of the microcapsule. The accuracy of the elastic deformation of polymer capsule can be ensured using a cantilever of mediate stiffness. Our results show that the existence of the hydrogen-bonding layer makes the multilayered polyelectrolyte harder in comparison with the pure multilayered polyelectrolyte capsules.     

From hollow shells to artificial cells: biointerface engineering on polyelectrolyte capsules

Biomimetic composites can be fabricated by coating hollow polyelectrolyte capsules with biological interfaces such as a phospholipid membrane and proteins. Polyelectrolyte capsules have been templated applying the Layer-by-Layer technique of polyelectrolyte assembled on decomposable cores, which are destroyed after the assembly of the polyelectrolyte multilayer. Phospholipid vesicles of 200-300 nm size are spreaded on the capsule wall forming a continuous lipid membrane. Further functionalisation of the outer capsule wall can be achieved with fused virions and recrystallised S-layers. Compartimentation of the capsule interior with lipid vesicles has been possible by using a solvent exchange method. The functionalisation of the outer capsule surface with biomolecules, together with the creation of internal compartments in the capsule, open new nanobiotechnological challenges towards the fabrication of artificial cells.     

Release behavior of active material from poly(vinyl amine)/polyelectrolyte composite hollow particles

Polyvinyl amine (PVAm) hydrogel hollow particles treated by layer-by-layer (LbL) assembly methods were fabricated. The structures of the prepared particles were confirmed through zeta-potential measurements and scanning electron microscopy (SEM). In addition, the loading amount and release rate of Chromotrope 2R (CR) from the prepared particles in each deposition step was investigated. The loading amount had an alternating tendency according to an increase in the layer number. When the outermost layer consisted of poly(sodium 4-styrenesulfonate) (PSS), CR permeation was prevented by ionic repulsion between the PSS and CR. On the other hand, CR easily permeated into the particles when the outermost layer was poly(diallyldimethyl ammonium chloride) (PDDA). The release rate was then changed by ionic interaction between the CR and the cationic polyelectrolyte and by the ionic repulsive force between the CR and the anionic polyelectrolyte. These results indicate that PVAm hydrogel hollow particles treated by the LbL method could potentially be used in the controlled release of water-soluble materials.     

Mn、Sb掺杂NBT—KBT—BT无铅压电陶瓷的研究

采用传统陶瓷制备工艺,利用XRD、SEM等测试分析方法,研究了MnCO3、Sb2O3掺杂对压电陶瓷晶体结构、表面形貌以及性能的影响。研究结果表明：所有组成均呈单一钙钛矿型固溶体特征,无其它晶相生成。掺杂陶瓷在1160℃左右烧结比较合适。MnCO3表现为典型的“受主”添加物特征。Sb2O3的掺杂对陶瓷性能的影响受多种因素共同作用,当Sb2O3的掺杂量为0.1％（质量分数）时,d33=148pC／N、tanδ=4.2％、εr=1516。MnCO3的掺杂可以促进晶粒生长,Sb2O3的掺杂使晶粒尺寸的均匀性降低。     

Synthesis and characterization of ratiometric ion-sensitive polyelectrolyte capsules

Micrometer-sized polyelectrolyte capsules are synthesized, which have ion-sensitive fluorophores embedded in their cavities. As the membranes of the capsules are permeable to ions, the fluorescence of the capsules changed with the ion concentration. In particular, capsules sensitive to protons, sodium, potassium, and chloride ions are fabricated and their fluorescence response analyzed. In order to allow for ratiometric measurements, additional fluorophores whose emission do not depend on the ion concentration and which emit a different wavelength are co-embedded in the capsule cavities.     

Mn改性Na0.5Bi2.5Nb2O9高温压电陶瓷的研究

采用固相法获得了Mn改性的Na0.5Bi2.5Nb2O9(NBN+xmol%MnCO3,0≤x≤10.0)铋层状压电陶瓷,并系统地研究了Mn(掺杂)对NBN基陶瓷显微结构与电性能的影响.结果表明,所有获得的样品都是居里点在700℃以上的单一相铁电体.加入Mn显著地提高了NBN系列陶瓷的机械品质因素Qm,明显改善了陶瓷的压电与机电性能.当MnCO3掺杂量为8.0mol%时,陶瓷获得最佳电性能:tanδ=0.749%,d33=20 pC/N,Qm=3120,kp=12.37%,kt=21.09%,Pr=7.01μC/cm2.NBN+xmol%MnCO3(x=8.0)陶瓷经700℃退极化处理后,其d33保持为原来的75%(~15 pC/N),表明该材料在高温领域下具有良好的应用前景.     

基于负载过氧化氢酶的介孔二氧化硅粒子的酶场效应晶体管生物传感器

制备了基于负载辣根过氧化氢酶(HRP)的介孔二氧化硅(MS)粒子的酶场效应晶体管(ENFET)用来检测过氧化氢浓度的生物传感器。不同孔径的MS粒子被用作固定酶的载体构造ENFET,显著改善了酶的固定量。用负载HRP的MS粒子修饰于离子敏场效应管的栅极制成的过氧化氢敏ENFET灵敏度较传统的直接固定HRP的ENFET有显著的提高。对不同孔径的MS粒子研究发现,扩孔的MS粒子的性能更好,同时还讨论了缓冲液浓度和pH值的影响。另外,由于在MS粒子表面组装了5个复层的聚电解质,生物传感器的稳定性良好。     

Characterization of hollow silica–polyelectrolyte composite nanoparticles by small-angle X-ray scattering

Hollow silica–polyelectrolyte composite nanoparticles were prepared using templates of spherical polyelectrolyte brushes which consist of a polystyrene (PS) core and a densely grafted linear poly(acrylic acid) shell. The obtained hollow particles were systematically studied by small-angle X-ray scattering (SAXS) in combination with other characterization methods such as transmission electron microscopy and dynamic light scattering. The hollow structure formed by dissolving the PS core was confirmed by the reduction of electron density to zero in the cavity through fitting SAXS data. SAXS revealed both the inward and outward expansions of the hollow silica–polyelectrolyte composite particles upon increasing pH from 3 to 9, while further increasing pH led to the partial dissolution of silica layer and even destruction of the hollow structure. SAXS was confirmed to be a unique and powerful characterization method to observe hollow silica nanoparticles, which should be ideal candidates for controlled drug delivery.     

Microemulsion-mediated solvothermal synthesis and morphological evolution of MnCO3 nanocrystals

The morphology- and size-controlled synthesis of MnCO3 nanocrystals was successfully achieved by cationic surfactant-CTAB-microemulsion-mediated solvothermal method. Various comparison experiments with different reactant concentrations and molar ratios between water and CTAB, showed the evolvement law of the morphology and size of the as-synthesized MnCO3 nanocrystals. With slowly increasing the concentration of reactants and/or molar ratio between water and CTAB, the morphology of MnCO3 nanocrystals changed gradually from cube to parallelepiped, and then rhombohedron, whereas the size decreased a little. The effect of the experimental parameters on the shapes and sizes of samples, such as the source of carbonate salts, reaction time, and temperature, were also discussed. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the products.     

Structural and Dielectric Properties of Dy-doped( Ba, Sr, Ca) TiO3 Thick Films

Preparation and electrecatalytic activities of Pt-TiO2 nanotubes （Bao.57Sr0.33 Cao.10 ）TiO3 powders, prepared by the sol-gel method, were doped MnCO3 as acceptor and Dy2O3 as donor. This powder was mixed with an organic vehicle and BSCT thick films were fabricated by the screen-printing techniques on alumina substrate. The structural and dielectric properties of BSCT thick films were investigated with variation of Dy2O3 amount. As a result of the differential thermal analysis （DTA）, exothermic peak was observed at around 670℃ due to the formation of the polycrystalline perovskite phase. All the BSCT thick films showed the XRD patterns of a typical polycrystalline perovskite structure. The average grain size of BSCT thick films decreased with increasing amount of Dy2O3 . The relative dielectric constant and dielectric loss of the BSCT thick film doped Dy2O3 0.1mol% were 4637.4 and 1.6% at lkHz, respectively.