碳纳米管/中间相炭微球复合材料锂离子电池负极材料研究

采用热缩聚法(温度为420℃、反应时间为2 h)制备出碳纳米管/中间相炭微球复合材料。研究了碳纳米管添加量对中间相炭微球的形成和形貌的影响,以及对碳纳米管/中间相炭微球复合材料充放电性能的影响。实验结果表明,5%(质量分数)的碳纳米管添加量有利于中间相炭微球的形成,碳纳米管/中间相炭微球复合材料作为负极材料的锂离子电池充放电容量可达到337 mAh/g,20次循环后容量仍保持88%。     

木薯淀粉微球的制备及表征

以海南特有的木薯淀粉溶液和椰子油作为水相和油相,以毒性极低的三偏磷酸钠为交联剂,采用反向乳化法制备出木薯淀粉微球.通过研究乳化剂、交联剂、NaOH浓度等因素对载药量的影响,得到最佳制备工艺条件.采用扫描电镜(SEM)、XRD、TGA等对所制备的木薯淀粉微球进行了表征,结果表明制备的木薯淀粉微球呈表面粗糙的圆球形,平均大小为20μm左右.     

碳纳米管对中间相炭微球制备的影响

以中温煤沥青和碳纳米管为原料进行热缩聚反应,制备出含有碳纳米管的中间相炭微球,采用扫描电子显微镜(SEM)、激光粒度仪和X射线衍射(XRD)等分析手段对其形貌及结构进行了表征。研究了添加碳纳米管对中间相炭微球形貌、粒径、产率、微晶结构及热缩聚工艺的影响。结果表明添加碳纳米管能够促进小球成核,阻止小球的融并长大,使炭微球的粒径减小,分布均匀,但过多的碳纳米管会导致球形度变差及中间相沥青产率的降低;碳纳米管的存在使石墨片层尺寸减小,石墨化程度降低;碳纳米管经过酸煮处理后,可以获得球形度更好、含有更大比例碳纳米管的中间相炭微球。     

层-核结构纳米硼酸钡/石蜡微球的合成与摩擦学研究

采用相转移技术合成了直径为6～30nm的无定型硼酸钡粒子,采用TEM、XRD对其结构进行了表征.将此纳米粒子与石蜡复合制备出层-核结构纳米硼酸钡/石蜡微球,用光学显微镜对其形貌进行了观察,大小在40～70靘之间.将微球加入水中制备出水基润滑剂,采用环块与四球摩擦磨损试验机对润滑剂的抗磨减摩性能进行了评价,发现相转移合成过程中表面活性剂的用量对纳米硼酸钡的形貌具有决定性影响.由此制备的水基润滑剂的摩擦学性能显著依赖于微球在润滑剂中的含量,尤其是纳米硼酸钡在微球中的含量,SEM表征发现石蜡在摩擦副上形成了膜.纳米硼酸钡的存在提高了抗磨减摩膜的强度.     

乳液模板法制备聚酰亚胺中空微球及其形貌调控EI北大核心CSCD

以聚酰胺酸(PAA)为前驱体、甲基硅油(SO)为油相、乙醇和水作为沉淀剂,采用乳液模板法制备了聚酰亚胺(PI)中空微球。重点研究了沉淀剂中乙醇的比例、PAA溶液的固含量及PAA溶液/SO体积比对微球粒径和形貌的影响;采用光学显微镜、扫描电镜、红外光谱和热重分析仪对微球的形成过程、粒径和形貌、化学结构和热稳定性进行了表征。当沉淀剂中乙醇/水体积比为1:1、PAA溶液固含量为6%、PAA溶液/SO体积比为1:1时,PI微球的粒径为4.75μm。制备出的PI中空微球均具有较好的热稳定性,其起始热分解温度为442℃。     

碳纳米管对中间相炭微球抗氧化性能的影响

通过原位热缩聚、模压成型、高温烧结制备了中间相炭微球/碳纳米管复合块体材料,采用热重分析和恒温氧化方法研究了碳纳米管对中间相炭微球抗氧化性能的影响。结果表明:原位添加适当比例的碳纳米管可以增强中间相炭微球的抗氧化性能。随着碳纳米管含量的增加,碳化处理后的炭材料微晶层间距变小,抗氧化性能增强;当添加5%碳纳米管时,样品初始失重温度提高了40℃,氧化10小时后质量损失仅为8.55%;但过多的碳纳米管会使微球粒径分布变宽,球形度变差,导致块体材料气孔率增加,降低了其抗氧化性能。     

提高采收率用聚(N-羟甲基丙烯酰胺-丙烯酰胺)微球的反相微乳液聚合及其性能

以煤油为连续相,50.0wt%N-羟甲基丙烯酰胺(N-MAM)、丙烯酰胺(AM)单体水溶液为分散相,Span80/OP-10为乳化剂,依据拟三元相图配制了含50.6wt%油相、42.0wt%水相、7.4wt%Span80/OP-10(质量比6∶1)乳化剂相的W/O微乳液(质量分数)。以N,N-亚甲基双丙烯酰胺(MBAA)为交联剂,在65℃过硫酸铵(APS)引发下进行反相微乳液聚合制备了纳米级交联P(AM/NMAM)微球。以微球粒径及溶胀性为考察指标,从单体配比、交联剂用量、引发剂用量及搅拌速率等方面对合成条件进行了优化。结果表明,在单体配比m(AM)∶m(N-MAM)为4∶1,交联剂MBAA用量0.60wt%、引发剂APS用量0.50wt%(以单体总质量计)、搅拌速率1000r/min的条件下合成的微球耐盐性好、吸水倍率高,在1.0×10~5 mg/L模拟地层水中可达18.40g/g。扫描电子显微镜(SEM)、透射电子显微镜(TEM)对微球形态的表征结果显示,其具有较好的球形度及单分散性,粒径分布均一,约为100nm左右。流变及岩心封堵实验表明微球胶乳具有良好的注入性,封堵效果显著,可实现逐级深部调剖。     

新型磁性海藻酸钠复合微球的制备与表征

以碳包铁(Fe@C)纳米粉作为磁性内核,用海藻酸钠作表层高分子,以正庚烷为油相,AOT为表面活性剂,氯化钙、环氧氯丙烷作交联剂,通过反相微乳法制备出了碳包铁/海藻酸钠核壳微球,系统考察了海藻酸钠的浓度、交联剂用量等对所制复合纳米微球性质的影响,并对产物进行了初步的性能表征.结果表明,选择合适的海藻酸钠的浓度、交联剂用量和其它相关参数,可以制备出外观为球形、分散性好、平均粒径约为250nm、具有强磁响应性的复合微球.     

内水相结构对微球包封率及控释行为的影响

采用水-油-水双乳化溶剂挥发法制备了聚乳酸-羟基乙酸共聚物(PLGA)/氧氟沙星载药微球,并考察了介孔硅、透明质酸、多聚赖氨酸不同内水相成分对微球粒径及其分布、表面形态、包封率以及释放特性的影响。研究结果表明,采用该方法制备出了内部具有多孔结构的载药微球;透明质酸内水相组微球平均粒度最大,粒径分布最小;介孔硅和透明质酸的加入提高了微球包封率;3种内水相组的初期爆释均高于对照组;多聚赖氨酸内水相组释放速率最快,透明质酸内水相组释放速率最慢。释放拟合曲线表明,4组不同内水相的微球,在释放区间内,释放行为都符合Slogistic方程式。     

复合CaCO3法制备医用多孔明胶微球

采用W/O型乳化-固化法制备了明胶CaCO3复合微球,将此复合微球用盐酸处理除去表面CaCO3,得到多孔的明胶微球.以差示扫描量热法、热重分析、红外光谱、扫描电子显微镜等方法对复合微球和多孔明胶微球的物理性质进行了表征,同时探讨了多孔明胶微球的合成机理.结果表明,两种微球中均含有CaCO3;扫描电镜显示,微球表面呈多孔结构,粒径在20～40μm之间.     

Fabrication and characterization of porous poly(lactic-<Emphasis Type="Italic">co</Emphasis>-glycolic acid) (PLGA) microspheres for use as a drug delivery system

In this work, Simvastatin (SIM) loaded porous poly(lactic-co-glycolic acid) (PLGA) microspheres were fabricated using the W/O/W1/W2 double emulsion and solvent evaporation method. The optimal conditions for fabricating porous PLGA microspheres were determined to be 20% distilled water (v/v), 10% PLGA (m/v), and a 4:1 ratio of internal polyvinyl alcohol (PVA) to dichloromethane (DCM). The pores size distribution of porous PLGA microspheres was varied from 0.01 to 40 μm, while their particle displayed a bimodal size distribution that had two diameter peaks at around 100 μm and 500 μm. The SIM encapsulation efficacy was found to be very high with a yield near 80% and the porous PLGA microspheres showed the excellent biocompatibility. In addition, the drug release profile was found to be significantly different from a temporal basis. Base on the combined results of this study, SIM loaded PLGA microspheres holds great promise for use in biomedical applications, especially in drug delivery system or tissue regeneration.     

Preparation of chitosan–hyaluronate double-walled microspheres by emulsification-coacervation method

Chitosan (CHS)−hyaluronate (HA) double-walled microspheres were prepared by emulsification-coacervation method. Tripolyphosphate (TPP) acted as ion crosslinker. The effects of oil/water volume ratio, surfactant, solution pH, TPP concentration, HA concentration, and emulsification time on microspheres fabrication and morphology were examined by Zeta (ζ) potential, Scanning electron microscopy (SEM) and Fourier-transform infrared spectrometry (FT-IR). It was found that TPP concentration, solution pH, surfactant and emulsification time were crucial factors for microspheres fabrication. Spherical microspheres with smooth surface were formed when TPP concentration was 8% or higher. The optimal pH for microspheres formation ranged from 6.0 to 7.0. As for surfactant, the microspheres obtained when span80 was applied alone were shapelier compared with those obtained when both span80 and tween80 were applied. With insufficient emulsification time, vacuous microcapsules, but not compact microspheres were formed. In addition, oil/water volume ratio and HA concentration also affected the microspheres morphology, but less importantly.     

Adsorption behavior of carbon nanotubes on polystyrene surfaces

Polystyrene (PS) was prepared using two different polymerization methods (dispersion polymerization and seed polymerization) to investigate the steric stabilizer effect during the adsorption process of carbon nanotubes (CNTs) on the surface of PS microspheres. Experiments with different microsphere diameters and difference types of CNTs were conducted to analyze the curvature effect of the spheres on the adsorption mechanism. The results showed that PS microspheres prepared through dispersion polymerization exhibited preferable adsorption behavior compared to PS spheres prepared through seed polymerization, suggesting that poly(N-vinylpyrrolidone) led to improved adsorption interactions between the CNTs and the PS microspheres in the CNTs dispersion. Additionally, the PS diameter and CNT curvature were examined with respect to the adsorption behavior between the PS microspheres and the CNTs. Multiwalled carbon nanotubes (MWCNTs) were found to be well adsorbed on the surface of PS microspheres measuring 2 microm. However, the MWCNTs were adsorbed much less on the surface of submicron-sized PS microspheres, compared with thinwalled carbon nanotubes (TWCNTs). On the other hand, TWCNTs were found to be suitable for adsorption on submicron-sized PS microspheres. These results also indicate that the curvature of the CNTs and the polymer microspheres are important to the CNT adsorption process.     

An inexpensive route to prepare mesoporous hollow silica microspheres using W/O ethanol/edible soybean oil macroemulsion as the template

Mesoporous hollow silica microspheres were prepared by using W/O emulsion consisting of ethanol droplets as a template in edible soybean oil. Ethanol droplets containing ammonia solution were generated by employing ultrasonication in pure soybean oil. The droplets were colloidally stabilized by means of a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Later on, another proportion of soybean oil dissolving tetraethyl orthosilicate (TEOS) was added to the W/O emulsion. The sol-gel reaction of TEOS was achieved only at the interface of the emulsion droplets, resulting in hollow silica microspheres. After washing the resultant with acetone, mesoporous hollow silica microspheres were simply obtained. Throughout this liquid template-based process, mesoporous hollow silica microspheres can be inexpensively synthesized without employing solid templates.     

加水量对水解法合成多孔二氧化硅微球的影响

为研究加水量对水解法合成多孔二氧化硅微球的影响,在十六烷基三甲基溴化铵-正硅酸乙酯-氨水-水体系中,在增加水用量的稀释条件下合成多孔二氧化硅微球,对微球的物质结构、形貌、孔结构等特性进行研究。结果表明:加水量还影响生成的多孔二氧化硅微球的大小、球形度、分散性及孔参数。反应体系未加水时,合成的二氧化硅微球的尺寸较小,球形度不高,比表面积和孔容均很小;增加水的用量对溶液稀释时,十六烷基三甲基溴化铵在水-醇溶液中形成胶束并作为模板,使正硅酸乙酯水解后在其上进行自组装,形成介孔二氧化硅微球。     

Study on purification and tip-opening of CNTs fabricated by CVD

The purification effects of different methods including liquid oxidation by nitric acid and multi-step treatment on two raw CNT samples fabricated by CVD under different synthesis conditions were investigated. Opening effects of the purified CNTs were also explored. The results showed that the liquid oxidation by nitric acid has some effects on purification and opening of the CNTs, and that the effects vary with the CNT morphologies. When using multi-step treatment method, apparent effects of purification and opening on the CNTs are obtained.     

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。     

An Investigation of the Synthesis of Poly(D, L-Lactic Acid) and Preparation of Microspheres Containing Indomethacin

Seven batches of poly(D, L-lactic acid) (PLA) were prepared from D, L-lactic acid using tetraphenyltin or zinc acetate as a catalyst. The samples of PLA were characterized by terminal group analysis, gel permeation chromatography, infrared analysis, and differential scanning calorimetry. Polymerization conditions such as the time of reaction and the type of catalyst affected the molecular weight of PLA. Microspheres containing indomethacin were prepared by the oil/water (o/w) solvent evaporation technique using different formulations and process variables. The in vitro release of indornethacin in phosphate buffer was found to be dependent on the molecular weight of PLA and also on the type and amount of adjuvants used. The batch of microspheres containing 5% cholesterol released the drug at a slow controlled rate (29%, 65%. and 85% in 1, 7, and 24 hr, respectively). The results of F test for the microspheres revealed that there is no significant direrence between the Higuchi model and the power law equation. The drug was released by a dimsion mechanism from the microspheres.     

An Investigation of the Synthesis of Poly(D,L-Lactic Acid) and Preparation of Microspheres Containing Indomethacin

Abstract

Seven batches of poly(D, L-lactic acid) (PLA) were prepared from D, L-lactic acid using tetraphenyltin or zinc acetate as a catalyst. The samples of PLA were characterized by terminal group analysis, gel permeation chromatography, infrared analysis, and differential scanning calorimetry. Polymerization conditions such as the time of reaction and the type of catalyst affected the molecular weight of PLA. Microspheres containing indomethacin were prepared by the oil/water (o/w) solvent evaporation technique using different formulations and process variables. The in vitro release of indornethacin in phosphate buffer was found to be dependent on the molecular weight of PLA and also on the type and amount of adjuvants used. The batch of microspheres containing 5% cholesterol released the drug at a slow controlled rate (29%, 65%. and 85% in 1, 7, and 24 hr, respectively). The results of F test for the microspheres revealed that there is no significant direrence between the Higuchi model and the power law equation. The drug was released by a dimsion mechanism from the microspheres.     

Carboxymethyldextran/magnetite hybrid microspheres designed for hyperthermia

Recently, organic–inorganic hybrids composed of derivatives of dextran, a polysaccharide, and magnetite nanoparticles have attracted much attention as novel thermoseeds. If they can be fabricated into microspheres of size 20–30 μm, they are expected to show not only hyperthermia effects but also embolization effects in human liver and kidney cancers. In this study, we examined the fabrication of carboxymethyldextran/magnetite microspheres using a water/oil emulsion as the reaction medium. Improvement of the chemical stability of the microcapsules by coating with silica using a sol–gel process was also investigated. The obtained hollow microspheres contained particles of size 20–30 μm. Silica coating using an appropriate catalyst for hydrolysis and polycondensation of alkoxysilanes was found to be effective for preventing dissolution and collapse in simulated body environments.