两亲性嵌段共聚物PMnEOS-b-PAA的可控合成及与PS-b-PAA共组装体的形貌

在苯乙烯单体的对位引入具有亲水性链段的乙二醇单元, 利用可逆加成断裂链转移聚合方法(RAFT), 可控合成了几种新的两亲性嵌段共聚物聚(4-乙烯基苄基乙二醇单甲醚)-b-聚丙烯酸(PMnEOS-b-PAA, n=1~3), 对其温敏和pH敏性质进行了初步研究. 同时, 研究了PMnEOS-b-PAA分别在亲水性环境下(四氢呋喃/水)和亲脂性环境下(四氢呋喃/甲苯)自组装体的形貌. 将聚对二乙二醇单甲醚苯乙烯-b-聚丙烯酸与聚苯乙烯-b-聚丙烯酸按质量比1:1[m(PMDEOS-b-PAA)/m(PS-b-PAA)=1:1]共混进行共组装, 在四氢呋喃/甲苯体积比为2∶1的混合溶剂中, 发现了一类新型具有均匀分布内部孔道且表面光滑的球形组装体. 进一步研究了该组装体的可重复性和组装机理, 为其后期应用于工业上的负载催化、 小分子识别与释放提供了一种新的策略.     

两种形貌纳米Fe2O3对TKX-50热分解的催化性能研究

Energy components used in solid rocket propellants are beneficial for improving the energy performance, and their thermal decomposition characteristics significantly affect the combustion properties of the propellants. As a kind of energetic material with both high energy and low sensitivity (impact and friction), 5, 5'-bistetrazole-1, 1'-diolate (TKX-50) can effectively improve the energy and safety characteristics of solid propellants. Burning catalyst is another important component of solid propellants, which can significantly improve the burning rate of the propellant and reduce the pressure exponent. Among various burning catalysts, nanoscale transition metal oxides can promote the thermal decomposition of the energetic component, thus enhancing the combustion properties of the solid propellant. However, the catalytic effects of nanoscale transition metal oxides with different morphologies on the thermal decomposition of TKX-50 have rarely been studied. Based on the excellent catalytic activity of Fe₂O₃ for TKX-50 thermal decomposition, nano-Fe₂O₃ particles with spherical and tubular microstructures were used for TKX-50 thermal decomposition. The Fe₂O₃ nanoparticles were successfully fabricated via the solvothermal method and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. The XRD, FT-IR, and XPS results confirmed the successful fabrication of spherical and tubular Fe₂O₃ samples. The SEM and TEM images showed that the spherical Fe₂O₃ samples are composed of agglomerated Fe₂O₃ nanoparticles with an average particle size of 110 nm. In addition, the average diameter and length of hollow tubular Fe₂O₃ nanoparticles are 120 nm and 200 nm, respectively. The catalytic activities of spherical and tubular Fe₂O₃ for TKX-50 decomposition were studied by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) methods. The DSC and TG-DTG curves showed that both tubular and spherical Fe₂O₃ could effectively promote TKX-50 thermal decomposition. The first thermal decomposition peak temperature (T_FDP) of TKX-50 was reduced by 36.5 K and 26.3 K in the presence of tubular and spherical Fe₂O₃, respectively, at 10 K·min⁻¹. The activation energy (E_a) of TKX-50, determined by the iso-conversional method, was significantly reduced in the presence of both tubular and spherical Fe₂O₃. The results indicated that the microstructure of the catalyst has a significant effect on its catalytic performance for TKX-50 thermal decomposition, and that tubular Fe₂O₃ with hollow microstructure possesses better catalytic activity than spherical Fe₂O₃. The excellent catalytic activity of tubular Fe₂O₃ can be attributed to the hollow microstructure, which has more active sites for TKX-50 thermal decomposition.     

Co9S8/MoS2异质结构的构筑及电催化析氢性能研究

利用前驱物形貌导向法,成功制备了Co₉S₈/MoS₂异质结构催化剂,该催化剂在碱性析氢反应（HER）中表现出优异的催化活性及稳定性,其在10 mA·cm^-2处的过电势仅为84 mV.通过X射线粉末衍射（XRD）、透射电子显微镜（TEM）、电子自旋共振（ESR）、拉曼光谱（Raman）、X射线光电子能谱（XPS）和同步辐射（XAFS）等表征,证明了CoS₂/MoS₂在H₂氛围下煅烧形成Co₉S₈/MoS₂的过程中,CoS₂中Co的配位模式从部分八面体向Co₉S₈中的四面体转变,这种转变可活化MoS₂的惰性平面,从而使其更有利于吸附H^*.除此之外,接触角数据表明：该催化剂具有良好的亲水性,有利于电解液渗透及气体分子的迅速扩散,从而促进HER反应速率.由于异质结构间具有强烈的相互作用,该催化剂可表现出良好的结构稳定性.本工作基于Co₉S₈/MoS₂异质结构的成功构筑及对其HER催化机理的充分探讨,为后续硫化物异质结及其在电催化中的应用提供了良好的思路和研究基础.     

激光溅射沉积制备的ZnO:Ga薄膜表面形貌分析

薄膜表面形貌定量研究有助于薄膜生长机理的认识.研究的薄膜是用激光脉冲沉积法(PLD)制备的ZnO:Ga(GZO)透明导电薄膜.由于GZO薄膜的生长是在远离平衡态情况下实现的,具备自仿射分形特征,可以用高度-高度相关函数进行描述.通过对用原子力显微镜(AFM)获得的表面高度数据进行相关运算,定量地分析了PLD制备的GZO...     

水热法制备二氧化钛微球的形貌控制及机理研究

以钛粉、Na OH和H2O2为原料,采用水热法成功制备出二氧化钛微球。利用X-射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和场发射扫描电镜(FESEM)对产物的结构、形貌和尺度进行了表征。结果表明,产物为金红石型Ti O2,微球的直径约为1~2μm,微球由许多纳米管组成。根据实验结果,讨论了二氧化钛纳米管的生长机理,初步研究了双氧水用量,水热温度以及煅烧温度等对产物形貌形成的影响。     

模具钢表面激光毛化工艺的试验研究

以模具工业45^#钢摩擦学设计及性能要求为基础，分析了激光毛化模具钢表面形貌的形成机理及其关键的影响因素。采用灯泵浦Nd：YAG脉冲激光器在试样表面进行激光毛化工艺试验，获得了合理的激光毛化参数范围：激光峰值功率0．8～1．6kW，离焦量-1．4～-0．4mm、＋0．4～4-1．4mm，辅助气体压力〉0．2MPa，脉宽1．8ms。采用功率增益和氧气保护，可加工出预先设定的微火山口状毛化形貌。微凹坑形貌的成功获得对于提高拉伸模具的摩擦磨损性能，进一步掌握激光毛化参数与材料的作用规律，提供了有效的数据参考。     

控制成核生长大尺寸C60，C70单晶

通过改进双温区双温度梯度方法，成功地控制成核密度，分别生长出线度可达6mm和5mm的大尺寸C₆₀，C₇₀单晶，并对其表面形貌和晶体结构进行了研究. 关键词：     

SiO2内保护层对LiB3O5晶体倍频增透膜损伤阈值的影响

 利用离子辅助电子束沉积方法在LiB₃O₅基底上镀制了不加SiO₂内保护层和加SiO₂内保护层的倍频增透膜，测量了两类薄膜在波长1 064 nm多脉冲辐照下的激光损伤阈值，获得了两种不同的损伤形貌，并对损伤原因作了初步探讨。实验结果表明：保护层的加入把由基底膜层界面缺陷吸收所决定的阈值改变到由HfO₂膜层内缺陷吸收所决定的阈值，显著提高了倍频增透膜的抗激光损伤能力。     

原子力显微镜与表面形貌观察

简要介绍原子力显微镜观察材料表面形貌的原理。运用原子力显微镜,观察CD,VCD,DVD和可擦写的VCD光盘的刻录划痕,分析各类光盘的刻录特征,指出原子力显微镜在观察材料表面微米至纳米尺度形貌是非常有效的。     

三维相位展开算法在精密运动测试中的应用

三维相位展开算法将基于空间的相位展开算法拓展到时间轴上,包含了一维时间和二维空间信息,适合于运动测试。通过建立一维时间相位展开算法的数学模型,分析了该算法运动测试的基本原理,讨论了在精密测试中的使用方法和适用范围,并对微谐振器的微结构进行运动测试。实验表明,算法在相位展开中引入时间信息,不仅消除了形变测量中需选取静止点为相位参考点或参考平面的限制,还可以同时测量物体表面某点纳米级的离面运动曲线和表面形变。