二维胶体晶体异质结构的制备及传感性

制备具有不同粒径和折射率的聚苯乙烯(PS)和聚甲基丙烯酸甲酯(PMMA)微球,采用多次尖端导流法制备多重二维胶体晶体异质结构(2D-CCHs)阵列,在2D-CCHs阵列的间隙处填充丙烯酸类凝胶,再将PS或PMMA模板微球去掉,得到传质速度更快的2D-CCHs反蛋白石凝胶.经扫描电子显微镜证实,所制备的异质结构胶体晶体均为二维结构,且排列较为规整.德拜衍射、反射光谱和结构色分析结果表明,2D-CCHs的光学性质主要是各单层二维胶体晶体阵列独立衍射的叠加.随着p H值由7降低至3,双层2D-CCHs反蛋白石凝胶的德拜衍射环直径均减小了约80 nm,表明2D-CCHs反蛋白石凝胶可应用于化学传感领域.     

采用微流注射法在光纤端面制备单层胶体微球薄膜

提出了一种在光纤端面制备单层胶体晶体薄膜的新方法——微流注射法,利用针尖微量注射胶体微球溶液,该方法可以在气/液界面直接形成大面积六角密排的周期纳米球阵列,面积达到平方厘米级别,再利用二维胶体单层膜的可转移性,将薄膜转移至到光纤端面衬底上,形成单层胶体微球有序薄膜.采用扫描电子显微镜和光谱分析仪对样品形貌、结构以及光学特性进行了表征和分析.电子显微镜图像表明,光纤端面的胶体晶体为六角密排阵列结构.透射光谱表明,该结构具有光子晶体的带隙特征,带隙的中心波长约为700和850 nm,与分析软件FDTD Solutions仿真结果相吻合.结合溅射沉积方法,得到了银纳米球壳阵列结构,检验了其局域表面等离子体共振效应(LSPR).对比讨论了溶液浓度、弯月面的形成及注射速度等因素对微流组装胶体微球薄膜质量的影响.     

TiO2掺杂调控聚苯乙烯微球折射率及胶体光子晶体结构色

胶体光子晶体由于其可调变的结构色在绿色印刷、印染等领域备受关注,而其光子带隙的宽度和位置由光子晶体的晶格参数(晶面间距,通常受胶体微球尺寸影响)和介质的折射率决定。现有人工胶体光子晶体主要基于SiO_2和高分子(如聚苯乙烯(PS)等)微球的组装制备,由于胶体微球材质种类有限,折射率调控受限,因而目前调控胶体光子晶体结构色主要靠改变胶体微球的尺寸来实现。本文首先制备高折射率(2.6)的TiO_2纳米晶,在乳液聚合制备单分散的PS(折射率1.6)微球过程中,将所制备的TiO_2纳米晶掺杂于PS微球中,通过TiO_2的掺杂量有效调控胶体微球的折射率,进而实现胶体光子晶体的结构色调控。以多色胶体光子晶体微球的水溶液为墨水,采用彩色喷墨打印技术打印了电脑设计的光子晶体彩画。本文发展的光子晶体结构色调控新技术拓展了胶体光子晶体的应用。     

Pickering乳液聚合制备核-壳结构PS-SiO2复合微球

用二氯二甲基硅烷对纳米SiO2粒子进行疏水改性,当其表面Zeta电位由-54.8 mV变成-25.8 mV时,SiO2粒子就能在苯乙烯-水界面自组装,形成稳定的Pickering乳液,即以胶体粒子为乳化剂的乳液.利用Pickering乳液聚合制备了以聚苯乙烯(PS)为核、纳米SiO2为壳的PS-SiO2复合微球.用FT-IR、XPS、SEM、偏光显微镜等对复合微球进行了表征.结果表明:复合微球由聚苯乙烯和纳米二氧化硅粒子组成,二氧化硅粒子以单层、六方密排的方式分布在聚苯乙烯微球表面.     

悬浮液气-液界面二元胶体颗粒的漂浮组装机理

提出一种在悬浮液气-液界面漂浮组装亚微米单分散聚苯乙烯(PS)微球和纳米SiO2颗粒二元胶粒晶体的新方法, 并系统研究了漂浮组装机理. 研究表明, 聚苯乙烯微球和二氧化硅两种胶体颗粒在悬浮液气-液界面的漂浮组装是以PS微球的组装为主导的. 在一定PS微球相浓度范围内, 悬浮液中PS 微球与SiO2颗粒的初始体积配比基本不影响PS微球有序组装的形成. PS微球粒径在150-500 nm时易于形成有序排列, 较小或较大粒径的PS微球难以形成有序排列. SiO2颗粒的组装是一种以PS微球为“基底”的沉积过程. 二元胶粒晶体中SiO2颗粒的体积分数由其在混合悬浮液中的相浓度所决定.     

P(St-AM)核壳聚合物微球的制备及其光子晶体膜

采用一步乳液聚合法,调节引发剂用量,制备了不同粒径的具有核壳结构的功能性聚(苯乙烯-丙烯酰胺)乳胶微球.用透射电子显微镜表征了乳胶微球的核壳结构和粒径,所制微球的粒径分别为195,217,234和255 nm.用红外光谱对微球的化学成分进行了表征,证实聚丙烯酰胺已包覆在聚苯乙烯外层.通过竖直沉积自组装法制备了聚合物微球的光子晶体薄膜.扫描电子显微镜表征了所制光子晶体膜的表面形貌,反射和透射光谱表征了光子禁带.结果表明,聚合物微球以面心立方紧密堆积,其(111)面与基底平行;微球粒径不同,光子晶体的光子禁带不同.制备了不同光子禁带的光子晶体,禁带分别位于473,515,574和630 nm,相应的薄膜分别呈蓝色、绿色、黄色和红色,对于光子晶体的拓展和应用具有重要的意义.     

聚苯乙烯/银纳米粒子复合微球的合成及催化性能

首先通过乳液聚合和浓硫酸酸化制备表面富含磺酸根的磺化聚苯乙烯(PS)微球(直径532 nm),再用其静电吸附[Ag(NH_3)_2]~+离子,最后采用聚乙烯吡咯烷酮还原表面吸附的[Ag(NH_3)_2]~+离子,得到了负载银纳米粒子的PS/AgNPs复合微球.采用扫描电子显微镜、透射电子显微镜、紫外-可见光谱、红外光谱和X射线衍射表征了PS/AgNPs复合微球,并考察了其对甲基蓝(MB)的催化性能.结果表明,Ag纳米粒子高度分散在磺化PS微球表面;该PS/AgNPs复合微球对催化转化MB有较高的催化活性,并可多次重复利用.本研究在催化降解有机污染物方面有一定的实用价值.     

颗粒模板法制备大孔Al2O3材料

采用颗粒模板法制备了大孔氧化铝(Al2O3)材料. 扫描电子显微镜(SEM)结果显示, 大孔Al2O3结构中的大孔呈“囊泡状”且孔道的贯通性较差. Zeta电位测量表明, 共沉积条件下聚苯乙烯(PS)和Al2O3两种胶体颗粒带有相反的电荷, 在静电引力作用下先发生了吸附, 再沉积在一起. 吸附在PS微球表面的Al2O3纳米颗粒形成的吸附层是导致大孔呈“囊泡状”和孔道不贯通的主要原因. 采用聚二烯丙基二甲基氯化铵(PD)溶液对PS胶体微球带电性质进行了改性, PS微球的Zeta电位由−44.36 mV变成了+37.41 mV, 进而消除了沉积过程中二元颗粒间的吸附现象. 扫描电子显微镜显示, 大孔样品中“囊泡状”大孔消失, 同时孔道贯通性得到改善.     

微米级胶体晶体可控制备与红外波段光学特征研究

通过调整配方,得到了不同粒径的微米级单分散聚苯乙烯(PS)胶体微球,利用优化的垂直沉积法将PS胶体微球自组装成高质量的蛋白石型光子晶体材料,并通过激光粒度分析仪、扫描电镜和红外光谱仪等实验手段研究其可控制备与红外波段光学特征.其中由1.00和1.20μm PS单分散胶体微球自组装成的三维光子晶体的禁带位置分别为2.25、2.47μm,符合理论计算结果.该材料可改变目标红外波段的辐射特征,未来有望应用于热障涂层材料和红外隐身技术等领域.     

聚苯乙烯/银核/壳复合微球的制备及其表征

通过分散聚合法制备了单分散性好,粒径均一的聚苯乙烯(PS)微球.以PS微球为核,用浓硫酸进行表面改性,使其表面带有负电.加入一定量的[Ag(NH3)2]+溶液,由于静电吸引,使其吸附在PS微球表面,通过化学还原的方法制备了PS/Ag核/壳结构复合微球.采用透射电镜(TEM)、扫描电镜(SEM)、红外光谱(IR)、X射线衍射(XRD)以及紫外-可见光谱对PS/Ag复合微球进行表征.结果表明:通过PS微球的表面改性,在其表面引入了磺酸基团,提高了微球表面的电负性和亲水性,对包覆过程起到了很好的促进作用;通过稳定剂(PVP)和不同还原剂(一缩二乙二醇DEG和乙二醇EG)的使用,形成的PS/Ag核/壳复合微球形貌不一样,同时研究表明制备出的PS/Ag复合微球可以用于催化剂催化还原有机染料溶液,表现出很好的催化活性.     

纳米玉米醇溶蛋白微球稳定的O/W型Pickering乳液

利用相分离工艺制备玉米醇溶蛋白(zein)纳米微球,微球粒径可控制在40 nm左右;经旋转蒸发制得zein溶胶体系,zein溶胶具有明显的丁达尔现象,静置数月不聚沉,Zeta电位法测得zein微球在pH值为4.0时分散性能最佳。 以纳米zein微球为固相稳定剂制备O/W型Pickering乳液,考察了zein胶体加入量、油水体积比等因素对乳液稳定性的影响。 实验结果表明,zein胶体加入量的质量分数控制为0.4%,高油水体积比将有利于Pickering乳液的长时间稳定。 基于zein分子的两亲结构和界面组装特点,提出了zein微球稳定Pickering乳液的作用机制。     

In situ synthesis of sulfide-coated polystyrene composites for the fabrication of photonic crystals

Sulfide (CdS, ZnS, and SnS(2))-coated polystyrene (PS) nanocomposites with a diameter of about 160 nm were synthesized by an in situ synthesis method. The PS spheres adsorbed polyelectrolytes, which were coordinated with Cd(2+) and Zn(2+) reacted with sulfions released through the hydrolysis of thioacetamide in an aqueous bath. As to the SnS(2)-coated PS composite, we introduced a deposition method in which a thin layer of SnS(2) was deposited on the surface of PS spheres. The PS spheres assembled on the patterned substrate of porous aluminum oxide (PAO) were more regular than those on the nonpatterned microslide, so the PS spheres coated with CdS and ZnS composites were assembled into ordered arrays on the PAO substrate, respectively. And the obtained lambda(max) of CdS-coated PS colloid crystal array red-shifted 262 nm compared with that of the pure PS colloid crystal array. All the particles and colloid crystal arrays were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Energy-dispersive X-ray (EDX) was undertaken to determine the elements Cd, S, and Sn.     

漂浮法制备SiO2有序大孔材料

用漂浮组装方法以亚微米尺度单分散的聚苯乙烯(PS)微球作为模板, 在悬浮液气-液界面处组装PS模板微球与纳米级胶体颗粒, 形成二元胶体颗粒共混物, 再去除模板得到有序大孔材料.     

聚苯乙烯/Ag核壳结构纳米微粒的制备及表征

用种子乳液聚合法合成了聚苯乙烯（PS）/Ag复合纳米粒子,进一步利用分步聚合技术实现了聚甲基丙烯酸甲酯(PMMA)在微球表面功能化,分别用TEM、XRD、TG-DTA及FT-IR对其结构和形貌进行了表征,并考察了其摩擦学性能.结果表明,在所选择的实验条件下,合成了以Ag纳米微粒为核,PS、PMMA为壳层的核壳结构复合纳米微球,其中Ag纳米核平均粒径约12 nm,复合微球粒径约25 nm,颗粒较均匀并且在有机溶剂中有良好的分散性,作为润滑油添加剂,具有良好的抗磨性能.     

细乳液聚合法制备磁性复合微球及其表征

在制备超细Fe3O4 磁性粒子的基础上 ,以 3种低分子量聚合物Disperbyk 1 0 6、Disperbyk 1 0 8和Disperbyk 1 1 1为Fe3O4 微粒在单体相中的分散稳定剂 ,采用细乳液聚合法制备了平均粒径为 3 40nm的PS Fe3O4 磁性复合微球 .详细研究了分散剂种类对细乳液聚合制备磁性复合微球的影响 ,并采用XRD、TGA和TEM等手段对磁性复合微球的形态、结构及磁响应性等进行了表征 .实验结果证明分散剂的选择对磁性复合微球的成功制备起着至关重要的作用 ,兼具酸性和碱性功能基的分散剂Disperbyk 1 0 6具有更好的分散和稳定效果 .TEM结果表明 ,所制备的复合微球具有一些缺陷 ,而缺陷处往往是Fe3O4 磁性粒子聚集的地方     

Colloid-polymer mixtures in solution with refractive index matched acrylate colloids

Colloid-polymer (CP) mixtures extend between two limiting cases, the colloid limit with the polymer coil size small compared to the colloid radius Rcol and the protein limit with the colloidal particles much smaller in size than the radius of gyration of the polymer chains Rg. In the present work, model systems are developed for the protein limit. The colloid-solvent pairs are optimized in terms of their isorefractivity in order to facilitate the characterization of large polystyrene chains in suspensions of small colloids. The degree of isorefractivity of colloidal particles was successfully evaluated in terms of a reduced scattering intensity. Two polystyrene samples with radii of gyration of Rg = 96 nm and Rg = 78 nm, respectively, are used. The radii of the colloidal particles are close to Rcol = 12 nm, leading to size ratios of Rg/Rcol = 8 and Rg/Rcol = 6.5. Four colloid solvent systems were found to be suitable for polymer characterization by light scattering, one based on silica particles and three systems with acrylate particles. The present investigation is focused on the three acrylate systems: poly(methyl methacrylate) in ethyl benzoate (ETB) at 7 degrees C, poly(ethyl methacrylate) in toluene at 7 degrees C and poly(ethyl methacrylate) in ETB at 40 degrees C. Characterization of PS chains is for the first time performed in colloid concentrations up to 2.5% by weight. In all cases, the size and shape of the polymer chains remain unchanged. A slight mismatch of the colloid scattering or a limited colloid solubility prevented investigation of PS chains at higher colloid concentration.     

Rapid Synthesis of Monodisperse Polystyrene Microspheres and Self-Assembly of Colloidal Crystals on Mica

Polystyrene (PS) colloidal particles were prepared in aqueous solution by a quick emulsifier-free emulsion polymerization (EFEP) method. The scanning electron microscopy (SEM) images indicate that the as-synthesized particles have good sphericity and uniform size (dispersion coefficient C_v is less than 5%). The monodisperse PS microspheres with different diameter were obtained easily by varying the monomer concentration. The atomic force microscopy (AFM) images show that the PS microspheres were self-assembled into three-dimensional ordered structure on micas by dropping-casting method. The self-assembly method is simple and quick. Based on the experimental results, a possible self-assembly mechanism was proposed.     

Combination of microspheres and sol-gel electrophoresis for the formation of large-area ordered macroporous SiO2

A simple and effective fabrication scheme involving sequential electrophoretic depositions of polystyrene (PS) microspheres (500 nm and 1 μm in diameter) and SiO₂ sols (~ 5 nm in diameter) to produce large-area ordered macroporous SiO₂ inverse opals (2 × 2 cm²) on ITO substrates is demonstrated. The zeta potentials for PS microsphere suspension and SiO₂ sols are measured to determine an optimized processing window in which both samples carry negative surface charges and sol-gel transformation can be properly implemented. Our approach entails the electrophoresis of PS microspheres to render a colloidal crystal with negligible defects. Afterward, SiO₂ sols are infiltrated to the interstitial voids among the closely-packed PS microspheres via another electrophoresis process, followed by an oxidation treatment to remove the PS colloidal template and complete the densification of SiO₂ gels. The resulting SiO₂ inverse opals reveal impressive surface uniformity and structural integrity. Fourier transform infrared spectroscopy confirms the complete removal of PS microspheres, leaving an intact SiO₂ skeleton, whereas X-ray diffraction pattern indicates its amorphous nature.