功能型多孔聚合物微球的制备及其缓释性能研究

利用超声分散改进的二步溶胀法制备4～9μm的聚苯乙烯-二乙烯苯(PSt-DVB)多孔微球,并以防晒剂parsol 1789为模型组分考察了其缓释性能.通过SEM和BET等手段表征微球表面形貌和孔结构,并研究了超声分散时间、种球类型、交联单体浓度等因素对微球性能的影响.确认超声分散的应用可以明显缩短溶胀时间;种球的粒径和分子量受分散介质极性影响较大,种球的单分散性直接决定最终粒子的形貌;随交联单体浓度增大,微球比表面积上升、孔径下降.制得的多孔聚合物微球用作化妆品活性物载体时,具有良好的缓释作用.     

Assembly of ordered ZnO porous thin films by cooperative assembly method using polystyrene spheres and ultrafine ZnO particles

Ordered ZnO porous thin films were fabricated by cooperative assembly method using polystyrene sphere (PS) and ultrafine ZnO particles, in which ultrafine ZnO particles were directly assembled in the voids of PS while the template was being assembled by capillary forces. The influence of experimental parameters, such as evaporation temperature, ZnO concentration and the concentration ratio of PS/ZnO on morphology of the porous structure was mainly studied. The results showed that an ordered porous structure could be obtained by this method. X-ray diffraction (XRD) spectra indicated the porous ZnO thin film was wurtzite structure. The transmissivity decreased with the decrease of wavelength, but still kept above 80% beyond the wavelength of 550 nm. Optical band gap of the ZnO thin film was 3.13 eV.     

Stacks of functional oxide thin films patterned by micromolding

Stacks of up to five relief patterned functional oxide thin films were obtained by a low-cost and low-tech soft-lithographic patterning technique. Micromolding was used to pattern a film of a metal-organic precursor solution for Y-stabilized ZrO(2) (YSZO). Subsequent drying and pyrolysis yielded a line-patterned YSZO film. The process was repeated up to four times with a precursor solution for BaTiO(3) on top of the YSZO film, resulting in stacks of YSZO and BaTiO(3) lines with well-defined edges. This approach presents a step forward on the way to a versatile additive micropatterning technique with which simple multi-material device structures can be fabricated in a reliable, fast, and cost-effective manner.     

PS微球的制备及三维胶晶模板的组装和应用

研究了PS微球合成中单体、引发剂和乳化剂浓度以及聚合温度对粒径及分布的影响。采用高速离心沉淀法、恒温加热蒸发诱导法和自然沉降法对单分散PS微球进行了组装,得PS胶体晶体模板,并以其为模板制备了锂离子筛前驱体Li4Mn5O12。用纳米粒度及ZETA电位分析仪、扫描电子显微镜(SEM)、饱和交换容量等表征了材料的粒径及分布、形貌、结构和离子交换性能。结果表明:通过控制反应条件可以在一定范围内制得粒径均一、单分散性好、表面规整光滑的PS微球;PS胶体晶体模板三维有序,排列规整;酸改性后的离子筛前驱体对Li+饱和交换容量为7.49mol/g锂离子筛。     

Directed assembly of functional light harvesting antenna complexes onto chemically patterned surfaces

We report the directed assembly of the photosynthetic membrane proteins LH1 and LH2 isolated from the purple bacterium Rhodobacter sphaeroides onto chemically patterned substrates. Nanoimprint lithography was used to pattern discrete regions of amino-?and fluoro-terminated or poly(ethylene glycol) self-assembled monolayers onto a glass substrate. Densely packed layers of assembled protein complexes were observed with atomic force microscopy. The protein complexes attached selectively to the amino-terminated regions by electrostatic interactions. Spectral images generated with a hybrid scanning probe and fluorescence microscope confirmed that the patterned proteins retained their native optical signatures.     

Thin films of two functional oxides patterned laterally by soft lithography

Thin films of two laterally patterned functional oxides of uniform thickness were obtained in a two-step soft-lithographic micromolding process. CoFe(2)O(4)/ZnO and CoFe(2)O(4)/BaTiO(3) dual-phase patterns were fabricated. The films showed good replication of the pattern that was defined in the first patterning step. X-ray diffraction showed that the films consisted of two distinct phases, and magnetic force microscopy showed that the compounds were laterally separated, the separation pattern being the same as that of the initial soft-lithographic process. The films exhibited slight height variations near the edges of the phases, which were introduced in the first deposition step and were not fully compensated in the second deposition step. The films are sufficiently smooth to allow fabrication of multilayer structures.     

聚苯乙烯微球的可控制备研究

分别采用无皂乳液聚合法和分步乳液聚合法,使用过硫酸钾(KPS)为引发剂、聚乙烯吡咯烷酮(PVP)为稳定剂、十二烷基硫酸钠(SDS)为乳化剂制得单分散PS微米球和纳米球。讨论了引发剂、稳定剂、乳化剂等因素对PS球粒径大小的影响。研究表明,在一定范围内随着KPS、PVP、SDS用量的增加,PS球粒径逐渐变小,而粒径分布不变。通过调整KPS、PVP、SDS的用量,可以在10～1000nm范围内实现PS球的可控制备。     

Self-assembly versus directed assembly of nanoparticles via pulsed laser induced dewetting of patterned metal films

A nanoscale, synthetic perturbation was all that was required to nudge a natural, self-assembly process toward significantly higher order. Metallic thin film strips were transformed into nanoparticle arrays by nanosecond, liquid-phase dewetting. Arrays formed according to an evolving Rayleigh-Plateau instability, yet nanoparticle diameter and pitch were poorly controlled. However, by patterning a nanoscale sinusoid onto the original strip edge, a precise nanoparticle diameter and pitch emerged superseding the naturally evolving Rayleigh-Plateau instability.     

单分散中空聚苯乙烯微球制备

采用搅拌乳化方法制备水包油(W1/O)型乳状液,经膜乳化法制得单分散的复乳(W1/O/W2)型乳状液,再通过液中干燥法制得单分散中空聚苯乙烯(PS)微球.考察了shirasu porous glass(SPG)膜孔径对乳状液液滴粒径及粒径分布、表面活性剂浓度对PS微球中空率和单分散性的影响.由激光粒度分析仪结果及PS微球的SEM照片证实,制得的PS微球,粒径呈单分散,是SPG膜孔径的2.0～2.4倍且具有中空结构.     

图案化厚膜多孔硅制备与表征

图案化多孔硅是微电子、微机械、光电子器件的重要组成部分.实验以含Si3N4保护层的光刻单晶硅片为基底,采用电化学阳极氧化法制备图案化厚膜多孔硅,分析阳极氧化前后Si3N4保护层表面形貌变化特征和光刻尺寸对图案化多孔硅宽度、膜层厚度的影响规律,表征图案化多孔硅的结构、组成与发光性能.结果表明,氧化前Si3N4保护层局部区域出现枝晶,阳极氧化后形成不均匀孔状结构;制备的图案化多孔硅膜厚62～83μm,其横向扩展程度和膜层厚度均随光刻尺寸增大呈减小趋势;图案化多孔硅微结构含大量不规则裂纹和硅柱,新鲜制备的表面含Si-Hx键,其光致发光峰值波长650nm.     

多孔阳极氧化铝膜在纳米功能材料制备中的应用

纳米材料具有一系列不同于块体材料的新异特性,在许多领域都有着广阔应用前景。阳极氧化铝膜具有独特的多孔结构,可作为制备各种纳米功能材料的模板,因而在纳米功能材料制备中占有重要地位。本文综述了多孔阳极氧化铝模板的结构特征、制作方法及由模板合成法制备的多种纳米功能材料的研究与应用现状,并介绍了模板及纳米功能材料的常用表征手段。     

Preparation of uniform Silicalite-1 microspheres with large secondary pore architecture using monodisperse porous polystyrene particles as template

A new method was developed for preparation of silicalite-1 microspheres with uniform diameter about 2.5 μm using monodispersed micron-sized poly- styrene-co-divinylbenzene (PSD) porous particles as template. In this method, the PSD particles were impregnated first with tetraethoxysilane (TEOS) and then with tetrapropylammonium hydroxide (TPAOH). After crystallization and calcination, the silicalite-1 microspheres, possessing a regularly spherical morphology similar to the original silicalite-1, were successfully synthesized. More importantly, the silicalite-1 microspheres have large secondary pores in the range of 40 to 120 nm and high pore volume up to 0.7 cm³g^− 1. All these would facilitate the applications of microspheres in catalysis avoiding diffusion limitation.     

表面功能化聚苯乙烯磁性微球的制备及表征

以纳米级四氧化三铁(Fe3O4)为磁性载体,以苯乙烯(St)、丙烯酸(AA)和丙烯酸甲酯(MA)为单体,用微悬浮聚合法制备了表面功能化聚苯乙烯磁性微球,并对聚合过程中预处理、温度、Fe3O4/St比、分散剂的影响进行了讨论。扫描电镜照片和磁滞回线显示微球分散性好,具有超顺磁性;热失重-差热分析表明其磁含量高;红外光谱表明微球表面含有羧基基团;通过电导率仪测试,计算出了微球表面羧基含量。结果表明,丙烯酸甲酯改性的羧基磁性微球比丙烯酸改性的性能要好。     

Controlled fabrication of patterned lateral porous alumina membranes

Confined lateral alumina templates are fabricated with different pore sizes by changing the acid electrolyte and the anodization voltage. The control of the number of pore rows down to one dimension is also achieved, by controlling the thickness of the starting aluminum film as well as the anodization voltage. We observe that the mechanism of pore formation in the lateral regime is very similar to that in the classical vertical situation.     

The near field properties of colloidal polystyrene microspheres on silicon

We have investigated the optical resonance and near field inside and under absorptive polystyrene (PS) microspheres on Si wafers. Near field flat plane images of PS microspheres were numerically simulated. Nanostructures were prepared on Si substrates using the regular two dimensional (2D) arrays by a single pulsed laser irradiation (KrF, lambda = 248 nm). Periodical PS nanoparticle, PS nanoflowers and Si nanobumps were fabricated by different laser fluence. Mechanisms for PS particle size reduction and Si nanobump formation by laser irradiation were discussed on the base of the theoretical calculations. Good agreement between theoretical calculations and experimental results has been observed.     

Combustion synthesis of porous titanium microspheres

The synthesis of titanium porous microspheres by a combustion technique was studied under an argon atmosphere by using a TiO₂ − 2.5Mg reactive mixture. The precursor, a fine TiO₂ powder, was thermally treated in the range 600–1300 °C prior to the combustion experiments. TiO₂ microspheres whose diameters were between 10 and 50 μm were obtained from precursor particles annealed in the range 900–1100 °C. A biphase product consisting of Ti and MgO phases was obtained when the TiO₂ microspheres were reduced with Mg. The spherical morphology of the final particles was retained despite the relatively high combustion temperatures (1630–1670 °C) used in this study. Moreover, porous titanium microspheres were obtained when the MgO particles were dissolved using acid leaching. Scanning electron microscopy (SEM) images of the microspheres suggested that the spherical structure contained ∼0.5–2.0-μm-diameter porous windows. The Brunauer–Emmett–Teller (BET) surface area of the Ti microspheres was determined to be 2.8 m² g⁻¹.     

Preparation of silver nanoparticles stabilized on the surface of polystyrene microspheres

Silver nanoparticles stabilized on the surface of polystyrene microspheres have been prepared by reducing silver ammine with formaldehyde, without surface activation of the microspheres. The size distributions of the nanoparticles have been obtained, and the optical absorption spectra of the synthesized nanomaterials have been measured.