氧化石墨烯/二氧化硅协同改性环氧树脂复合材料的制备及表征

以氧化石墨烯(GO)、硅溶胶、甲苯二异氰酸酯为原料,合成二氧化硅接枝氧化石墨烯(SiO2-g-GO)化合物,并用于改性环氧树脂制备SiO2-g-GO/环氧树脂复合材料。采用红外光谱(FT-IR)、广角X射线衍射(WAXD)、热重分析(TGA)、动态机械分析仪(DMA)及扫描电镜(SEM)对复合材料性能进行表征。结果表明,当SiO2-g-GO用量为5 phr,材料冲击强度提高到38.79 kJ/m2,是纯环氧树脂的2.2倍左右;同时,拉伸强度、弯曲强度及弹性模量分别提高了1.35倍、1.45倍、1.42倍。TGA及DMA研究表明,改性后复合材料的起始分解温度、最大分解温度、储能模量和玻璃化转变温度Tg分别比环氧树脂有明显的提高。冲击断面的SEM表明,SiO2-g-GO对环氧树脂固化物有明显的增韧效果。     

Mn改性CdSe/CdS制备磁性荧光双功能材料及性能表征

以共沉淀法制备出表面羟基化的四氧化三铁(Fe_3O_4)磁性颗粒,通过柠檬酸(CA)修饰制备出Fe_3O_4/CA。三步法合成出具有较好荧光性能的CdSe(硒化镉)/CdS(硫化镉)量子点,并经锰(Mn)元素改性,使其具备更好的荧光特性。巯基乙酸(C_2H_4O_2S)为改性后量子点提供连接基团,经乙二胺(C_2H_8N_2)与Fe_3O_4/CA相连接。该材料经荧光分光光度计、荧光显微镜、透射电子显微镜(TEM)和振动样品磁强计(VSM)的表征。结果表明:通过乙二胺的连接(静电吸附及氢键作用),经Mn改性后的CdSe/CdS量子点成功与Fe_3O_4/CA连接,形成了具备磁性荧光双功能的复合材料,饱和磁化强度达到28.86emu/g,其优秀的磁性荧光性能在药物分离、靶向治疗等方面具有很高的应用价值。     

激光改性纤维对其增强环氧树脂复合材料力学性能的影响

利用激光对玻璃纤维、玄武岩纤维和碳纤维进行表面改性后,以环氧树脂为基体,分别制备三种纤维增强环氧树脂复合材料。利用SEM和万能试验机对表面改性前后的碳纤维形态、力学性能及三种纤维/环氧树脂复合材料的力学性能和断面形貌进行表征,研究了纤维激光表面改性对三种纤维及其增强环氧树脂复合材料力学性能的影响。结果表明:激光表面改性对碳纤维/环氧树脂复合材料的力学性能提升最高,其拉伸强度最大提高了77.06%,冲击强度最大提高了31.25%,玄武岩纤维/环氧树脂复合材料的力学性能提升次之,而玻璃纤维/环氧树脂复合材料的力学性能有所下降。因此,激光进行表面改性适用于碳纤维和玄武岩纤维。     

Fe_3O_4/OA/PANI@CdSe/CdS磁性荧光纳米复合物的制备及其表征

由共沉淀法制备出表面羟基化的Fe3O4,并用油酸(OA)进行了修饰。通过新颖简便的微悬浮方法制备出聚苯胺包裹的Fe3O4/OA/PANI。用三步法合成出具有良好的荧光性能的量子点CdSe/CdS。通过EDC交联剂的作用,将量子点CdSe/CdS和Fe3O4连接。该微粒经过透射电子显微镜(TEM)、能谱(EDS)、荧光分光光度计、荧光显微镜和振动样品磁强计(VSM)的表征。结果表明:通过PANI的桥梁作用(静电吸附和氢键作用),量子点CdSe/CdS成功连接到了Fe3O4/OA/PANI表面,得到了磁性荧光复合材料,该材料在药物传递、靶向治疗的应用上都具有很大潜力。     

GO负载纳米Al2O3对环氧树脂耐磨性能的影响

为了研究出一种耐磨性能优异的环氧树脂基纳米复合材料,将球形纳米氧化铝经γ-氨丙基三甲氧基硅烷改性后负载到氧化石墨烯表面,再将其作为填料加入到环氧树脂中,制备出球形纳米氧化铝/氧化石墨烯/环氧树脂新型纳米复合材料.利用硬度计、磨耗仪及万能试验机,分别对纳米复合材料的硬度、磨损量、弯曲性能和冲击性能进行测试.试验结果表明:该新型纳米复合材料相较于纯环氧树脂,磨损量减少了 52.5％;弯曲强度达到了 121.4 MPa,为纯环氧树脂的1.44倍;冲击强度达到了 27.4 J/m2,为纯环氧树脂的5.96倍.球形纳米氧化铝大的比表面积与表面作用力增强了片层状氧化石墨烯和环氧树脂的表面作用,进而使该新型纳米复合材料表现出了优异的耐磨性能.     

水溶性量子点制备条件的优化及表面修饰

以L-半胱氨酸为稳定剂在水溶液中合成CdSe纳米粒子,研究了水浴时间、水浴温度、不同L-半胱氨酸/Cd/Se比例、pH值等因素对其荧光光谱的影响,确定了最佳的合成方案.用CdS对其表面进行修饰,采用透射电镜、X射线衍射、光谱法等表征了Cdse/CdS核壳结构颗粒的形成,结果表明该纳米粒子发光强度明显高于单一的CdSe量子点,光谱峰位置有所红移;合成条件会显著影响CASe/CAS核壳结构量子点的荧光性能.     

激光对碳纤维及碳纤维/环氧树脂复合材料性能影响

采用高能激光束对聚丙烯腈（PAN）基碳纤维进行表面改性。利用SEM、EDS、FTIR、XRD、万能试验机等表征手段,对改性前后碳纤维微观形态、成分变化、物相结构、力学性能进行表征,系统地研究了激光束对碳纤维微观组织变化、性能变化等的影响规律,探索激光束对碳纤维的作用机制。结果表明,碳纤维经激光表面改性后,其表面的粗糙度和比表面积增加,碳纤维的浸润性得到提升,且激光束的功率越高、扫描速度越低,碳纤维浸润性越好。改性后的碳纤维化学成分、微观结构及官能团种类没有改变;改性后的碳纤维官能团种类没有改变,说明激光改性过程主要以物理过程为主;激光改性没有改变碳纤维的微观结构,改性后微晶尺寸略有减小,有利于改善碳纤维与环氧树脂的界面黏结性能。激光表面改性碳纤维/环氧树脂复合材料的拉伸强度和冲击强度均有不同程度的提高,当碳纤维质量分数为0.2wt%、激光改性功率为150 W时,碳纤维/环氧树脂复合材料的拉伸强度提高了59%,冲击强度提高了52%。     

4,4′-二氨基二苯甲烷改性氧化石墨烯/环氧树脂复合材料的制备及性能研究

采用4,4′-二氨基二苯甲烷(DDM)处理氧化石墨烯(GO),将处理后的氧化石墨烯(GO-DDM)与环氧树脂(EP)充分混合制备了改性氧化石墨烯/环氧树脂复合材料(GO-DDM/EP)。通过红外光谱(FT-IR)、X射线衍射(XRD)和透射电子显微镜(TEM)等分析方法对GO-DDM进行表征,采用电子万能试验机和悬臂梁冲击试验机对制得的复合材料进行力学性能测试。结果表明:DDM成功地接枝在GO的表面,极大提高了GO在有机溶剂中的分散性,且GO不再分散在水中。当复合材料中的GO-DDM含量为0.9%时,其拉伸强度提升了64.9%,冲击强度提升了17.0%。     

双功能磁性荧光纳米复合Fe_3O_4/PMIDA@CdSe/CdS微粒的制备与表征

以FeCl_3·6H_2O和FeSO_4·7H_2O为原料,制得磁性Fe_3O_4纳米颗粒。利用静电吸引合成了双甘膦包裹的Fe_3O_4/双甘膦(PMIDA),使磁性微球表面连上大量的功能基团羧基,再与乙二胺通过键合使磁性微球外面修饰着氨基。将修饰过巯基乙酸的量子点CdSe/CdS与磁性微粒混合,量子点表面的羧基与Fe_3O_4表面的氨基进行连接。对其进行荧光分光光度计,透射电子显微镜(TEM)、振动样品磁强计(VSM)和荧光显微镜等表征,结果表明:复合后的微球具备很好的发光性能和优越的磁性能。     

联苯型热致性液晶接枝氧化石墨烯的合成及应用

以氧化石墨烯(GO)、4,4′-二(β-羟乙氧基)联苯(记为BP2)、环氧氯丙烷(ECH)等为原料,合成联苯型液晶接枝氧化石墨烯(LCE-g-GO)化合物,用于改性环氧树脂(EP)制备LCE-g-GO/EP复合材料。采用红外光谱(FT-IR)、差示扫描量热(DSC)、偏光显微镜(POM)、广角X射线衍射(WAXD)、热重分析(TGA)及扫描电镜(SEM)对复合材料性能进行表征。结果表明,当LCE-g-GO用量为5%,冲击强度提高到35.06 kJ/m2,是纯环氧树脂的2倍左右;同时,拉伸强度及弯曲强度分别提高了1.47、1.70倍,呈典型的韧性断裂。改性后复合材料的起始分解温度比环氧树脂明显提高,当LCE-g-GO用量为5%时,复合材料的起始分解温度达到375℃,比环氧树脂(351℃)提高了24℃。     

Probing the cytotoxicity of CdSe quantum dots with surface modification

The cytotoxicity of CdSe quantum dots (QDs) with surface modification was reported first in the paper. CdSe QDs were incorporated into poly (d, l) lactide (PLA) nanoparticles and then surface modified with Fluronic® 68 (F-68), cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), respectively. Three different particle sizes and zeta potential of the surface modified CdSe QDs were produced using a nano-precipitation method. The cytotoxicity of the surface modified CdSe QDs was evaluated in HepG2 cell model with MTT viability assay. The results showed that the cytotoxicity of the surface modified CdSe QDs in vitro was dependent on the surface properties. Surface modification with F-68 and SDS could lessen the cytotoxicity of CdSe QDs, while surface modification with CTAB showed significant cell damage. CdSe QDs surface modified with F-68 were injected into mice and the fluorescence images in viscus were obtained. The results suggested that CdSe QDs surface modified with F-68 have low cytotoxicity and good potential for biological labeling and imaging applications.     

Encapsulation of CdSe/ZnS nanocrystals within mesoporous silica spheres

Quantum dots (QDs) have attracted much attention on account of their unique optical and electronic properties. Applications of QDs in biological systems face challenges owing to their toxicity and hydrophobicity. Incorporation of QDs in mesoporous silica spheres affords not only hydrophilic shell for QDs in order to enhance their dispersion in aqueous medium, but also offers chemically inert shielding to reduce QD cytotoxicity. In the current work, two types of mesoporous silica encapsulated QDs were synthesized by rationally adjusting the reaction conditions. Mesoporous silica coated single CdSe/ZnS nanoparticles (sCdSe/ZnS@mSiO₂) were prepared through the one-pot reaction. Further modification of this reaction offered hollow mesoporous silica spheres (CdSe/ZnS@HMSS) encapsulating multiple CdSe/ZnS QDs assembled on the internal surface of the spheres. Both of sCdSe/ZnS@mSiO₂ and CdSe/ZnS@HMSS show significant photophysical properties. Possible formation mechanism of the two types of nanostructures was investigated and discussed.     

Effect of fibre content and alkali treatment on mechanical properties of Roystonea regia-reinforced epoxy partially biodegradable composites

The present paper investigates the effect of fibre content and alkali treatment on tensile, flexural and impact properties of unidirectional Roystonea regia natural-fibre-reinforced epoxy composites which are partially biodegradable. The reinforcement Roystonea regia (royal palm) fibre was collected from the foliage of locally available royal palm tree through the process of water retting and mechanical extraction. The poor adhesion between fibre and matrix is commonly encountered problem in natural-fibre-reinforced composites. To overcome this problem, specific physical and chemical treatments were suggested for surface modification of fibres by investigators. Alkali treatment is one of the simple and effective surface modification techniques which is widely used in natural fibre composites. In the present study both untreated and alkali-treated fibres were used as reinforcement in Roystonea regia epoxy composites and the tensile, flexural and impact properties were determined at different fibre contents. The alkali treatment found to be effective in improving the tensile and flexural properties while the impact strength decreased.     

Optimization of CdSe layer on modified ZnO hierarchical spheres by spin-SILAR for efficient CdS/CdSe co-sensitized solar cells

In this study, after CdS quantum dots sensitized ZnO hierarchical spheres (ZnO HS), we used a simple process to deposit CdSe QDs on ZnO by spin-coating-based SILAR, and applied to photoanodes of quantum dots-sensitized solar cells. Before CdS and CdSe QDs deposition, the ZnO HS photoanodes were modified by Zn(CH₃COO)₂·2H₂O methanol solution to further enhance the open-circuit voltage and power conversion efficiency (PCE). The program of modifying photoanodes and the number of CdSe spin-SILAR cycles are evaluated on the optical and electrochemical properties of the cells. As a result, a high energy conversion efficiency of 2.49 % was obtained by using modified ZnO HS/CdS photoanode under AM 1.5 illumination of 100 mW cm^?2. And further decorated by the CdSe QDs, the ZnO HS/CdS/CdSe cell achieved a PCE of 5.36 % due to the modification of ZnO HS nanostructure, the enhanced absorption in the visible region, the lower recombination reaction and higher electron lifetime.     

酚化酶解木质素-环氧树脂/环氧树脂复合材料的合成及性能

以酶解木质素(EHL)为原料,采用苯酚-硫酸法对其进行酚化改性,所得酚化木质素(PL)在碱性条件下,与环氧氯丙烷(ECH)合成木质素-环氧树脂(L-EP),利用FT-IR对产物进行表征。探讨单因素反应条件对酚化工艺的影响。结果表明:反应时间3.0h、反应温度95℃、2mol/L H_2SO_4用量为4mL/g时,木质素的酚化效果最佳,其酚羟基含量达到4.632mmol/g,较EHL提高42%。研究了不同L-EP添加量对L-EP/环氧E-51复合材料力学性能和热性能的影响。结果显示:L-EP的添加量为5%时,L-EP/环氧E-51复合材料的拉伸强度最好,较纯E-51提高26%;随着L-EP添加量的增加,L-EP/环氧E-51复合材料的热稳定性增强。采用非等温法分析环氧E-51和L-EP/环氧E-51复合材料的固化动力学,结果证明:L-EP对复合材料固化有一定的促进作用。     

Cyto-/genotoxic effect of CdSe/ZnS quantum dots in human lung adenocarcinoma cells for potential photodynamic UV therapy applications

Quantum dots (QDs) are luminescent nanoparticles (NPs) with promising potential in numerous medical applications, but there remain persistent human health and safety concerns. Although the cytotoxic effects of QDs have been extensively investigated, their genotoxic effects remain under-explored. This study scrutinized the cyto- and genotoxic effects of QDs with a Cadmium selenide/Zinc sulfide (CdSe/ZnS) core/shell, and suggests comprehensive guidelines for the application of QDs in cancer therapy. QDs were used to treat A549 cells in the presence and absence of ultraviolet A/B (UVA/UVB) irradiation. QD-induced cell death was evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), apoptosis, and lactate dehydrogenase (LDH) assays, as well as by real-time PCR analysis of differential mRNA levels of genes, such as ataxia telangiectasia mutated (ATM), p53, and caspase-9, involved in apoptosis. The genotoxic effect of CdSe/ZnS QDs was measured in human cancer cells, for the first time, by comet and micronucleus assays. Treatment with CdSe/ZnS QDs and UVB irradiation resulted in the most severe extent of cell death, indicating strong induction of phototoxicity by CdSe/ZnS QDs in the presence of UVB. Both apoptotic and necrotic cell death were observed upon QDs and UVB combined treatment. The induction of Olive tail moments and micronuclei formation was also most significant when CdSe/ZnS QDs and UVB irradiation were combined. Our results on the genotoxic effect and mechanistic details of CdSe/ZnS QD-induced cell death suggest that UVB irradiation is the most effective method for increasing the potency of QDs during photodynamic cancer therapy.     

Highly luminescent CdSe/ZnSe core-shell quantum dots of one-pot preparation in octadecene

CdSe/ZnSe core-shell quantum dots were synthesized using a new one-pot procedure where the core was prepared in octadecene. A ZnSe shell around a CdSe nanoparticle was formed by the reaction of selenium-richness on the surfaces of CdSe nanoparticles with Zn2+ from the injected zinc stearate precursor. The optical properties, luminescence kinetics, and the effect of shell thickness of as-prepared QDs were studied, which verifies the high quality of the resulting QDs. The new approach is effective not only for preparing core/shell QDs, but also for reducing the complexity of synthesis, toxicity, and reagent cost.     

氧化石墨烯改性玄武岩纤维及其增强环氧树脂复合材料性能

为了改善玄武岩纤维/环氧树脂复合材料的界面性能,通过偶联剂对氧化石墨烯进行改性,并将改性后的氧化石墨烯引入到上浆剂中对玄武岩纤维进行表面涂覆改性,同时制备了氧化石墨烯-玄武岩纤维/环氧树脂复合材料.采用FTIR表征了氧化石墨烯的改性效果;运用SEM分析了改性上浆剂处理对玄武岩纤维表面及复合材料断口形貌的影响和作用机制.结果表明:偶联剂成功接枝到氧化石墨烯表面;玄武岩纤维经氧化石墨烯改性的上浆剂处理后,表面粗糙度及活性官能团含量增加,氧化石墨烯-玄武岩纤维/环氧树脂界面处的机械齿合作用及化学键合作用增强,界面黏结强度得到改善,玄武岩纤维的断裂强力提高了30.8%,氧化石墨烯-玄武岩纤维/环氧树脂复合材料的层间剪切强度提高了10.6%.     

Synthesis and photoluminescence of bright water-soluble CdSe/ZnS quantum dots overcoated by hybrid organic shell

Photoluminescence properties from water soluble CdSe/ZnS QDs encapsulated with hybrid trioctylphosphine-poly(acrylamide-co-acrylic acid)-ethanolamine (TOPO-PSMA-EA) shell have been investigated. It was found that PL efficiency of CdSe/ZnS QDs in water was increased 5–30% after introducing PSMA-EA polymers to encapsulate CdSe/ZnS-TOPO QDs. Higher PSMA concentrations were found to enhance the PL efficiency of QDs up to 1.8 folds, which is ascribed to a better packing and passivation of the TOPO-PSMA-EA shell over the QDs. Time-resolved photoluminescence suggested that the mean lifetime of photoexcited carriers in the water-soluble CdSe/ZnS-TOPO-PSMA-EA QDs elongated 2–17 ns compared with that of uncoated samples, indicating that PL quenching defects were effectively removed for CdSe/ZnS QDs with hybrid TOPO-PSMA-EA shell.