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。     

聚（N-异丙基丙烯酰胺-co-丙烯酸）/Fe3O4复合微球的制备及表征

采用Fe3O4、N-异丙基丙烯酰胺(NIPAM)和丙烯酸(AA)制备了具有磁敏、温敏和pH敏感的多重敏性复合微球。先使用共沉淀法制备Fe3O4磁性纳米颗粒,并用油酸对其改性。继而采用种子聚合法制备P(NIPAM-co-AA)磁性微球。研究表明,在pH值为10的合成条件下,复合微球的分散性较好。采用疏水性引发剂可相对增加有机、无机相之间的亲和性。通过扫描电镜(SEM)、红外光谱(FT-IR)、动态光散射(DLS)和超导量子干涉磁强计(SQUID)等对微球进行了结构与形态表征,结果证明,复合微球形貌统一,各组分之间聚合良好。复合微球的粒径约为249 nm,对温度、pH可作出预期的响应,饱和磁化强度为40 emu/g。     

一步法制备羧基聚苯乙烯共聚荧光微球及其表征

以苯乙烯和丙烯酸/甲基丙烯酸为单体、烯丙基荧光素为荧光染料,采用一步法制备了两种粒径均一、表面羧基化的聚苯乙烯共聚荧光微球。用环境扫描电子显微镜、荧光显微镜、红外光谱仪、荧光分光光度计等对其形貌、结构和性能进行表征。结果表明:所制备的两种羧基化共聚荧光微球单分散性好、荧光性能好且稳定,表面成功引入了羧基;聚合在共聚荧光微球中的荧光素与烯丙基荧光素性质一致,证实了共聚荧光微球和烯丙基荧光素在乙醇和甲苯中具有不同荧光光谱。     

羧基功能化聚苯乙烯荧光微球的制备及表征

以苯乙烯、丙烯酸为单体,引入疏水性荧光染料罗丹明6G(Rh6G),采用微乳聚合法制备羧基聚苯乙烯荧光微球,并分析了表面活性剂、引发剂、丙烯酸用量对产物粒径分布的影响,考察了羧基聚苯乙烯荧光微球的浓度对荧光强度的影响。通过粒度分析仪、扫描电子显微镜、红外光谱仪、紫外吸收光谱以及荧光光谱仪对样品的纳米特性、形貌、结构和荧光性能进行了表征。结果表明,用微乳聚合法制备出50~250nm的羧基聚苯乙烯荧光微球,粒径均一且呈单分散性。紫外光谱图测试表明,在533nm左右有吸收峰。荧光光谱测试表明,羧基功能化的荧光聚苯乙烯微球浓度≤0.01%,其荧光最大激发峰为527nm,最大发射峰在555nm处;浓度高于0.01%时,荧光光谱出现红移,且荧光强度减弱。     

纳米尺度PS/Ag核壳结构复合球的制备与表征

采用分步法制备了聚苯乙烯/银(PS/Ag)核壳结构复合纳米球。首先采用无皂乳液聚合法并利用丙烯酸(AA)的羧基对制备的PS球进行改性,使其表面带负电荷;然后通过静电吸附作用在改性PS球的表面沉积[Ag(NH3)2]+,水浴(80℃)环境中利用十二烷基磺酸钠(SDS)作为还原剂将PS球表面的[Ag(NH3)2]+还原,制备出PS/Ag核壳结构复合球。通过动态激光粒度分析仪和透射电子显微镜对PS/Ag核壳纳米球的粒度分布、形貌和结构进行了表征,研究了AA的用量对复合球粒径及包覆的Ag壳厚度的影响。结果表明,随着AA用量的增大,所包覆的银层更加致密,厚度增大,当AA用量为15%时可得到Ag完全包覆的PS/Ag复合纳米球。     

层层自组装法制备碳包覆的Fe_3O_4碳量子点磁性荧光双功能材料

通过化学共沉淀法制备Fe_3O_4磁性纳米颗粒,在其表面包覆碳层,形成Fe_3O_4@C磁性微球,采用层层自组装法将聚二烯丙基二甲基氯化铵(PDDA)修饰到微球表面。将该微球与表面富含羧基的碳量子点(CQDS)连接,得到碳包覆的Fe_3O_4@CQDS(Fe_3O_4@C@CQDS)磁性荧光双功能复合微球。通过X射线衍射(XRD)、振动样品磁强计(VSM)、扫描电子显微镜(SEM)、荧光分光光度计和荧光显微镜等表征手段对该复合微球进行结构表征以及性能测试。结果表明:复合微球粒径约为50nm,饱和磁强度为23.39emu/g,这种性能优异的磁性荧光双功能复合微球有望在生命科学领域得到广泛应用。     

羧基功能化聚甲基丙烯酸甲酯微球的制备与表征

采用分散聚合、无皂乳液聚合,经皂化水解,分别制备出羧基含量不同的4种单分散功能化聚甲基丙烯酸甲酯微球。利用FT-IR、SEM、电导率等手段研究了不同制备方法,皂化过程等对微球的形态、表面羧基含量的影响,结果显示:通过改变反应原料配比、皂化时间等能可控制备出0.25μm、0.45μm、0.8μm等粒径不同的羧基功能化微球;利用丙烯酸修饰的聚甲基丙烯酸甲酯微球经皂化水解可显著提升微球表面的羧基含量至0.26mmol/g。     

P(St-co-AA)聚合物模板法制备中空SiO2微球研究

以无皂乳液聚合法制备的苯乙烯(St)和丙烯酸(AA)阴离子型无规共聚物[P(St-co-AA)]微球为模板,不经过分离和离心、表面改性等任何后处理过程,采用溶胶-凝胶方法直接进行二氧化硅(SiO_2)包覆,成功制得中空SiO_2微球。探究了氨水用量、正硅酸乙酯(TEOS)用量以及不同AA用量对中空SiO_2微球的影响,并对制得的SiO_2微球进行了表征。研究结果表明,制得的中空SiO_2微球分散性优异,体系中无SiO_2实心小粒子,粒径均一,表面形貌呈树莓状,微球壁厚可控制在5～30nm范围内。     

有机微球填充水性环氧涂层的制备及其防腐性能

用无皂乳液聚合法制备单分散的聚甲基丙烯酸甲酯(PMMA)和聚苯乙烯(PS)微球,将其添加到水性环氧树脂中制备出有机微球/水性环氧复合涂料,然后用空气喷涂法在钢片表面制备出复合涂层。用动态光散射(DLS)和扫描电子显微镜(SEM)对制备的有机微球进行了表征,用电化学测试(EIS)、盐雾测试和附着力测试等手段研究了不同颜基比(颜料和树脂的质量比:P/B)的有机微球/水性环氧复合涂层的耐蚀性。结果表明,两种有机微球的粒径均一且具有高度的单分散性,颜基比P/B=0.007的PS/水性环氧复合涂层具有最佳电化学、耐盐雾和附着力性能。复合涂层的抗介质渗透能力明显优于清漆涂层,因为有机微球独特的表面效应提高了涂层的致密性。     

表面含羧基磁性高分子复合微球的制备

用化学共沉淀法制备了F e3O4纳米微粒,并对F e3O4微球表面进行改性,以磁性F e3O4为核,通过苯乙烯和丙烯酸的乳液共聚,制备了粒径均匀、以苯乙烯和丙烯酸共聚物为壳、表面含有一定羧基的磁性高分子纳米复合微球。测定了此微球的形态、结构和粒径,探讨了聚合单体、乳化剂等因素对微球合成的影响。     

Fe3O4/SiO2/CMCH/CdTe荧光磁性微球的合成与表征

利用St ber法和交联法制备出具有荧光和磁性功能的Fe3O4/SiO2/CMCH/CdTe微球,并对其性能和应用效果进行了分析讨论.首先以正硅酸四乙酯为前躯体,Fe2＋和Fe3＋物质的量的比为1∶2,利用超临界干燥法制备出了Fe3O4/SiO2复合微球;并通过透射电镜对其进行观察,Fe3O4颗粒粒径为10 nm,SiO2层厚度为5 nm;其次羧甲基化的壳聚糖（CMCH）被嫁接在Fe3O4/SiO2表面上;然后利用水热法制备出CdTe荧光颗粒,通过壳聚糖与CdTe之间的静电吸引作用,CdTe被吸附在壳聚糖表面;最后利用戊二醛对壳聚糖的选择性交联作用制备出粒径在200 nm以内,饱和磁化强度为22.16 A.m2/kg,且具有良好荧光性能的Fe3O4/SiO2/CMCH/CdTe微球.荧光光谱分析表明最大发射波长从519 nm红移到528 nm,也证实了荧光颗粒CdTe成功吸附在Fe3O4/SiO2/CMCH表面.在动物实验中,该复合微球也显示出良好的荧光性、磁性及稳定性.     

Color-tuned FRET polystyrene microspheres by single wavelength excitation

Fluorescent monodisperse polystyrene microspheres were prepared by two-stage dispersion polymerization, which successfully covalently labeled microspheres with two dyes without disturbing the final particle size and size distribution. By varying the dye concentrations, microspheres show tuned colors with different fluorescent intensity under a single wavelength excitation. Fluorescence resonance energy transfer (FRET) between two labeled dyes was proved to contribute to the emission of the longer-wavelength dye at a shorter-wavelength excitation. There is no dye leakage for microspheres because of the covalent incorporation of dye molecules. The microsphere matrix provides good protection of dye molecules and blocks the influence of media outside on the fluorescence of microspheres. Single microsphere shows intense fluorescence due to a large number of encapsulated dye molecules. These uniform barcoding fluorescent microspheres have potential application in multiplexed bioanalysis.     

Using layer-by-layer assembly to fabricate NaLa(MoO4)2@CdTe core–shell microspheres with high fluorescence

The development of fluorescent materials with low energy consumption, low cost and desirable optical properties is needed for the perspective of practical application. Here, functional NaLa(MoO₄)₂@CdTe core–shell microspheres with high fluorescence were prepared by layer-by-layer self-assembly technique. Through the consecutive electrostatic adsorption of charged cetyltrimethyl ammonium bromide and CdTe quantum dots (QDs), the uniform and regular multilayer shell of CdTe QDs was synthesized. The NaLa(MoO₄)₂@CdTe microspheres exhibited improved photoluminescence intensity and stability of red emission, compared with that of the CdTe QDs powder, and the fluorescence enhancement mechanism were investigated. The CdTe QDs multilayer shell is expected to supersede the Eu³⁺ ion for producing a novel red phosphor.     

Flow cytometric ion detection with plasticized poly(vinyl chloride) microspheres containing selective lonophores

The use of flow cytometry as a rapid, high-throughput diagnostic tool for the analysis of ions is described. Monodisperse, uniform microspheres, which obey bulk optode theory and are governed by bulk extraction processes rather than surface phenomena, were prepared under mild, nonreactive conditions using a sonic stream particle casting apparatus. As an initial example demonstrating the utility of this approach, microspheres that contained a H+-selective fluorescent chromoionophore (ETH 5294), a cation-exchanger (NaTFPB), and either a highly sodium-selective (sodium ionophore X) or a potassium-selective ionophore (BME-44) were prepared. Separate solution analysis of sodium- and potassium-selective microspheres resulted in the generation of functional response curves using peak channel fluorescence intensities. The selectivity observed for both types of particles is sufficient for the clinical determination of Na+ and K+. Furthermore, sodium- and potassium-selective microspheres were analyzed in parallel using sodium sample solutions, resulting in the successful determination of sodium ion concentrations and providing important information about the selectivity of the potassium-selective sensors over sodium. This work demonstrates the potential applicability of flow cytometry as a means for developing multiplexed, rapid, high-throughput analyses for clinically relevant ions.     

Multicolor quantum dot encoding for polymeric particle-based optical ion sensors

Multicolor quantum dot-encoded polymeric microspheres are prepared with controllable and uniform doping levels that function as chemical sensors on the basis of bulk optode theory. TOP/TOPO-capped CdSe quantum dots and CdTe quantum dots capped with CdS (lambdaem = 610 and 700 nm, lambdaex = 510 nm) are blended with a THF solution of poly(methyl methacrylate-co-decyl methacrylate), poly(n-butylacrylate), or poly(vinyl chloride) plasticized with bis(2-ethylhexyl) sebacate without a need for ligand exchange. Polymeric microspheres are generated under mild, nonreactive conditions with a particle caster that breaks down a polymer stream containing the quantum dots into fine droplets by the vibration of a piezocrystal. The resulting microspheres exhibit uniform size and fluorescence emission intensities. Fluorescent bar codes are obtained by subsequent doping of two quantum dots with different colors and mass ratios into the microspheres. A linear relationship is found between the readout fluorescence ratio of the two types of nanocrystals and the mixing ratio. Quantum dot-encoded ion sensing optode microspheres are prepared by simultaneous doping of sodium ionophore X, chromoionophore II, a lipophilic tetraphenylborate cation exchanger, and TOPO-capped CdSe/CdS quantum dot as the fluorescent label. A net positive charge of the quantum dots is found to induce an anion-exchange effect on the sensor function, and therefore, an increased concentration of the lipophilic cation exchanger is required to achieve proper ion sensing properties. The modified quantum dot-labeled sodium sensing microspheres show satisfactory sodium response between 10(-4) and 0.1 M at pH 4.8, with excellent selectivity toward common interferences. The amount of the carried positive charges of the CdSe quantum dots is estimated as 2.8 mumol/g of quantum dots used in this study.     

Radiative exciton recombination dynamics in QD-tagged polystyrene microspheres

Fluorescent polystyrene microspheres are prepared by the incorporation of fluorescent CdSe/CdS core/shell semiconductor nanocrystals (quantum dots, QDs) using the emulsification/solvent evaporation method. The radiative exciton recombination dynamics is investigated by nanosecond time-resolved fluorescence spectroscopy at ambient conditions. The time constants of fast and slow fluorescence decay in QDs, dispersed in toluene, were 3.5 and 17.8 ns, respectively. For the QD-tagged microspheres, the time constants of fast and slow processes were ~2–3 and ~11–12 ns, respectively, and did not depend significantly on the QD-content of the microspheres. The fast decay component could be attributed to the recombination of delocalized exciton in the internal core states, and the slow component was attributed to the localized exciton in the surface states. It was found that the ratio of amplitudes of the fast and slow processes also changed after incorporation of QDs in microspheres. The observed differences in fluorescence decay between non-entrapped QDs and QD-tagged microspheres were probably due to energy transfer between the nanocrystals, which were in close proximity inside the microspheres. The obtained fluorescent QD-tagged microspheres are characterized by the other methods as well, which makes them of value for various applications as optical materials.     

P(St-EA-MAA)模板法制备中空二氧化硅微球

以种子乳液聚合制得的P(St-EA-MAA)共聚物微球为模板,γ-氨丙基三甲氧基硅烷(APS)为助结构导向剂,正硅酸四乙酯(TEOS)为硅源,制备了P(St-EA-MAA)/SiO2复合微球,经高温煅烧除去聚合物模板,得到了中空二氧化硅微球。热重分析(TGA)表明模板剂的最佳脱除温度为600℃。高分辨透射电镜(HRTEM)观察显示所制得的二氧化硅微球具有典型的中空结构和良好的单分散性,其尺寸主要取决于共聚物微球的大小,通过调节微球模板的尺寸可以有效控制中空微球的大小。N2吸附-脱附曲线显示二氧化硅壁具有丰富的微孔,比表面积、平均孔径和孔容分别为117.87m2/g、1.98nm和0.21cm3/g。在制备复合微球的过程中加入一定量的CTAB可以调整中空微球的壁厚和壁的孔结构,使其比表面积、平均孔径和孔容增加到219.79m2/g、3.89nm和0.25cm3/g。     

高效光催化降解气相苯纳米TiO2微球的制备EI北大核心CSCD

以四氯化钛为钛源,尿素为沉淀剂前驱物,硫酸钠为分散剂,利用水热法在水-醇体系中制备出纳米TiO2微球。运用X射线衍射、电子显微镜、N2吸附-脱附和紫外-可见光谱等手段表征样品的结构和性质,并考察了水热温度对纳米TiO2微球结构及光催化降解气相苯活性的影响。结果表明,此类微球由纳米颗粒组成,且比表面积大,介孔结构明显,光吸收出现明显的“蓝移”。光催化结果显示,微球具有很高的光催化活性,尤其是180℃下制备的微球仅用20min将苯完全去除,但生成CO2的量仍随时间有所增加,表明微球的强吸附性能促进其光催化降解过程,且矿化率高达5.5,是P25(2.7)的2倍。     

Facile fabrication of SiO2/Al2O3 composite microspheres with a simple electrostatic attraction strategy

SiO₂/Al₂O₃ composite microspheres with SiO₂ core/Al₂O₃ shell structure and high surface area were prepared by depositing Al₂O₃ colloid particles on the surface of monodispersed microporous silica microspheres using a simple electrostatic attraction and heterogeneous nucleation strategy, and then calcined at 600 °C for 4 h. The prepared products were characterized with differential thermal analysis and thermogravimetric analysis (DTA/TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS). It was found that uniform alumina coating could be deposited on the surface of silica microspheres by adjusting the pH values of the reaction solution to an optimal pH value of about 6.0. The specific surface area and pore volume of the SiO₂/Al₂O₃ composite microspheres calcined at 600 °C were 653 m² g⁻¹ and 0.34 ml g⁻¹, respectively.     

Preparation and characterization of ibuprofen-loaded microspheres consisting of poly(3-hydroxybutyrate) and methoxy poly (ethylene glycol)-b-poly (D,L-lactide) blends or poly(3-hydroxybutyrate) and gelatin composites for controlled drug release

Poly-(3-hydroxybutyrate) (P(3HB)) is a biodegradable and biocompatible polymer that has been used to obtain polymer-based drug carriers. However, due to the high crystallinity degree of this polymer, drug release from P(3HB) microspheres frequently occurs at excessive rates. In this study, two strategies for prolonging ibuprofen release from P(3HB)-based microspheres were tested: blending with poly(D,L-lactide)-b-polyethylene glycol (mPEG-PLA); and obtaining composite particles with gelatin (GEL). SEM micrographs showed particles that were spherical and had a rough surface. A slight decrease of the crystallinity degree of P(3HB) was observed only in the DSC thermogram obtained from unloaded-microspheres prepared from 1:1 P(3HB):mPEG-PLA blend. For IBF-loaded microspheres, a reduction of around 10 °C in the melting temperature of P(3HB) was observed, indicating that the crystalline structure of the polymer was affected in the presence of the drug. DSC studies also yielded evidence of the presence of a molecular dispersion coexisting with a crystalline dispersion in the drug in the matrix. Similar results were obtained from X-ray diffractograms. In spite of 1:1 mPEG-PLA:P(3HB) blends having contributed to the reduction of the burst effect, a more controlled drug release was provided by the use of the 3:1 P(3HB):mPEGPLA blend. This result indicated that particle hydration played an important role in the drug release. On the other hand, the preparation of P(3HB):GEL composite microspheres did not allow control of the IBF release.