基于POSS的ATRP引发剂的合成及其PMMA杂化材料制备

通过苯基三氯硅烷的水解、缩合合成了八苯基倍半硅氧(OPS),再经硝化、还原制备了八氨基苯基倍半硅氧(OAPS),在此基础上进一步合成了ATRP引发剂BOAPS,并运用FT-IR、NMR对产物的结构进行了表征.采用ATRP方法制备了PMMA/BOAPS杂化聚合物,运用GPC、DSC及TGA手段对杂化材料的结构与热性能进行...     

CPE／ZKF／EBP有机杂化材料的阻尼性能

研究了CPE/ZKF/EBP有机杂化材料的阻尼性能。DMA结果表明,部分EBP通过分子间氢键作用以侧基形式嫁接在氯化聚乙烯(CPE)分子链上,并且(2-羟基-3-环己基-5甲基)-苯环(ZKF)和2,2-甲撑双-(4-乙基-6-叔丁基苯酚)(EBP)对三元杂化材料的阻尼性能存在协同作用。当少量EBP加入CPE/ZKF体系时,不仅可以进一步改善CPE/ZKF/EBP三元杂化材料的损耗峰高度,而且损耗峰的位置也可以进行调节。进一步研究表明,三元杂化材料的阻尼性能主要依赖于ZKF/CPE的质量比,而EBP对三元杂化材料的阻尼峰位置的调控起到了重要的作用。     

基于玫瑰花瓣的双模板法制备高光催化活性的有序大孔-介孔锐钛矿二氧化钛薄片

以天然玫瑰花瓣和三嵌段共聚物P123(EO_(20)PO_(70)EO_(20))为双模板,有序大孔-介孔锐钛矿TiO_2薄片通过溶胶-凝胶法在酸性介质中成功制备。采用拉曼光谱、X射线衍射、N2吸脱附、扫描电镜和透射电镜对制备的TiO_2薄片进行表征。TiO_2薄片的光催化活性通过罗丹明B光降解过程的光催化效果来进行评价。结果表明多级构造的大孔-介孔TiO_2薄片为锐钛矿,且其三维有序的大孔孔壁均由有序的介孔所组成,其中,450℃煅烧后的TiO_2样品表观反应速率常数k达到2.21×10~(-2) min~(-1),表现出最高的光催化活性。     

助熔剂对陶瓷化硼酚醛复合材料热行为及微观结构的影响

以硼酚醛树脂(BPF)为基体,以纳米MgO、Al_2O_3和SiO_2(MAS)为成瓷填料,添加B_2O_3、Bi_2O_3或玻璃料等助熔剂,采用模压成型工艺制备MgO-Al_2O_3-SiO_2/硼酚醛(MAS/BPF)陶瓷化复合材料,研究助熔剂对MAS/BPF陶瓷化复合材料热稳定性、微观结构和物相转变的影响。结果表明:MAS/BPF陶瓷化复合材料在600~1000℃裂解2h后的尺寸收缩率为9%~14.5%,表现出良好的尺寸稳定性;TG热分析发现,助熔剂使MAS/BPF陶瓷化复合材料在1200℃时的残留率降低,但在900~1200℃的热稳定性提高。XRD和SEM分析结果显示,助熔剂能够显著降低陶瓷化反应温度。和B_2O_3、Bi_2O_3相比,玻璃料更有助于形成大量的液相,促进陶瓷化组分与裂解残余碳之间的反应,从而提高MAS/BPF陶瓷化复合材料在高温下的致密性和外形完整性。     

正己烷辅助合成小孔径大孔容介孔泡沫氧化硅材料

在正己烷-三嵌段共聚物(EO_(20)-PO_(70)-EO_(20),P123)体系中合成了小孔径大孔容介孔泡沫(MCF)氧化硅材料.采用高分辨扫描电镜、透射电镜、N_2吸附-脱附和小角XRD,对其孔道结构、型貌、比表面积、孔容等进行了表征.对合成条件的研究表明,在静置条件下水解TEOS合成的样品,其比表面积、孔径、孔容都比在搅拌下水解合成的样品明显增加,其中孔容可增加68%,达到2.32cm~3/g.     

非线性光学含氟PI/SiO2杂化波导纳米材料的研究

以含氟的二胺5,5'-(六氟异丙基)-二-(2-氨基苯酚)及二酐4,4'-(六氟异丙基)-苯二酸酐为单体.首先合成了经酰胺化的主链上带有活性羟基的含氟聚酰亚胺,再通过Mitsunobu反应将活性生色分子分散红1共价链接到聚酰亚胺的侧链骨架上,合成了二阶非线性光学(NLO)含氟聚酰亚胺.采用溶胶-凝胶技术,利用偶联剂APTES制备带有发色团的及含有硅氧烷端分子的聚酰胺酸,其中的Si(OR)3基经水解、缩合后,与正硅酸乙酯在催化剂作用下反应,经杂化、凝胶后,得到热稳定性高的杂化材料.将制得的含氟聚酰亚胺/SiO2杂化材料,利用FT-IR、SEM、TEM、XRD、DSC等手段对其进行了表征.杂化材料的玻璃化转变温度(Tg)为382℃,比纯聚酰亚胺的Tg(306℃)高76℃,表现出优良的高温热稳定性.     

块状PMMA/TiO_2有机-无机杂化材料的制备与表征

以钛酸丁酯为前驱体,在亚化学计量的水中水解,以硅烷偶联剂(MPMS)和丙烯酸为改性剂,采用溶胶-凝胶法制得均一、稳定的淡黄色二氧化钛溶胶,透射电镜分析粒径约20～30nm;在溶胶中加入甲基丙烯酸甲酯(MMA)和偶氮二异丁腈(AIBN),采用热固化方法制得淡黄色透明的PMMA/TiO2块体材料;通过TEM、FT-IR、DSC和TG表征杂化材料的微观结构和热性能.研究表明,杂化材料中PMMA和TiO2是以共价键连接的,TiO2均匀分散在PMMA中,两相之间没有明显的相分离现象;当w(TiO2)=20%时,杂化材料的玻璃化转变温度为175℃,比纯PMMA提高了约70℃,分解温度为300℃,比纯PMMA提高了120℃.     

聚醋酸乙烯酯/二氧化硅杂化材料的制备与性能研究

以硅酸钠在HCl溶液中的水解,经四氢呋喃(THF)萃取,制备聚硅酸溶胶,再与聚醋酸乙烯酯(PVAC)的THF溶液混合,经溶胶-凝胶过程制备了PVAC/SiO2有机/无机杂化材料.用扫描电镜(SEM),红外光谱(IR),X射线衍射,热失重及透光率等的分析测试,对制备的PVAC/SiO2杂化材料进行了结构与性能的研究.结果表明:本法制备的杂化材料中SiO2在PVAC的基体中分布均匀,SiO2在非晶态的PVAC中亦呈无定形态,杂化材料的硬度、软化温度和热分解温度都比纯PVAC有较大的提高;SiO2含量少于40%的杂化材料其断裂伸长率、屈服强度和断裂强度也比纯PVAC提高;另外,还发现在制备过程中加入少许偶联剂KH-570后,杂化材料中的有机-无机相间的相容性增加,不易发生相分离,材料的透光性能也大为改善.     

新型POSS基有机/无机纳米杂化材料的制备及光限幅性能研究

以二苯乙烯衍生物4-乙炔基-4′-硝基二苯乙烯(ENS)和POSS(T8H)为原料,通过钯催化硅氢化反应制备了POSS基有机/无机纳米杂化复合材料(POSS-ENS),并用IR、1H NMR、29Si NMR、UV-vis对其结构进行了表征.同时,对材料的光限幅性能和热性能进行了测试,结果表明,纳米杂化复合材料不仅对532nm、4ns脉宽的激光具有良好的光限幅效应,而且具有很好的光学稳定性和热稳定性能.     

纳米SiO_2/PVA杂化材料纸张表面增强剂的制备及性能

以正硅酸乙酯(TEOS),γ-氨丙基三甲氧基硅烷(KH-550)和聚乙烯醇(PVA)为主要原料,基于溶胶-凝胶(sol-gel)工艺,制备了一种纳米SiO2/PVA杂化材料,并将其用于纸张表面增强。通过红外光谱(IR),X射线衍射(XRD),差示扫描量热(DSC)和热重分析(TGA)对杂化材料进行表征,结果表明,纳米SiO2和PVA之间产生了化学键的结合,无机相的引入使杂化材料的热分解温度升高,结晶度降低。初步应用实验结果表明,当增强剂用量为1%时,纸张的环压指数提高27%,拉伸强度提高40%,撕裂度提高33%,拉毛强度提高35%。     

A General Strategy to Achieve Colossal Permittivity and Low Dielectric Loss Through Constructing Insulator/Semiconductor/Insulator Multilayer Structures

In this work, we propose a route to realize high-performance colossal permittivity (CP) by creating multilayer structures of insulator/semiconductor/insulator. To prove the new concept, we made heavily reduced rutile TiO₂ via annealing route in Ar/H₂ atmosphere. Dielectric studies show that the maximum dielectric permittivity (~?3.0?×?10⁴) of our prepared samples is about 100 times higher than that (~?300) of conventional TiO₂. The minimum dielectric loss is 0.03 (at 10⁴–10⁵ Hz). Furthermore, CP is almost independent of the frequency (100–10⁶ Hz) and the temperature (20–350 K). We suggest that the colossal permittivity is attributed to the high carrier concentration of the inner TiO₂ semiconductor, while the low dielectric loss is due to the presentation of the insulator layer on the surface of TiO₂. The method proposed here can be expanded to other material systems, such as semiconductor Si sandwiched by top and bottom insulator layers of Ga₂O₃.     

Electrical Characterization of Ordered Si:P Dopant Arrays

We report on the ability to fabricate arrays of planar, nanoscale, highly doped phosphorus dots in silicon separated by source and drain electrodes using scanning tunneling microscope lithography. We correlate ex situ electrical measurements with scanning tunneling microscope (STM) images of these devices and show that ohmic conduction can be achieved through the disordered array with a P coverage of 0.8times10¹⁴ cm^-2. In comparison, we show that an ordered array of P dots ~6 nm in diameter and containing ~50 P atoms separated by ~4 nm shows nonlinear I-V, characteristic of a series of metallic dots separated by tunnel barriers. These results highlight the use of STM lithography to pattern ordered dopants in silicon down to the sub-10 nm scale     

Laser‐Raman and Nuclear Magnetic Resonance (NMR) studies on plasma‐sprayed hydroxylapatite coatings: Influence of bioinert bond coats on phase composition and resorption kinetics in simulated body fluid

The structure and phase composition of HAp coatings deposited onto Ti6Al4V coupons (50x20x2mm) by atmospheric plasma spraying (APS) were studied by laser‐Raman spectroscopy, ³¹P‐ and ¹H‐MAS‐NMR and 2D‐³¹P/¹H HETCOR‐CP‐NMR spectroscopy, and XRD with Rietveld refinement. The samples investigated comprised APS HAp coatings with and without a TiO₂ bond coat as well as coatings incubated for different lengths of time (up to 12 weeks) in simulated body fluid (SBF) under physiological conditions. In APS coatings the presence of a bond coat increased the proportion of well‐ordered crystalline HAp at the expense of distorted apatite‐like structures such as oxyHAp and oxyapatite, and thermal decomposition products such as tricalcium phosphate (TCP) and tetracalcium phosphate (TTCP), and also decreased the amount of amorphous calcium phosphate (ACP). Incubation in SBF further advanced the proportion of crystalline HAp since the disordered structures, the thermal decomposition products, and ACP exhibit substantially higher solubility.     

Synthesis of ordered mesoporous Pd/carbon catalyst with bimodal pores and its application in water-mediated Ullmann coupling reaction of chlorobenzene

Heterogeneous palladium catalysts have been supported on the ordered mesoporous carbons (Pd/OMC) with bimodal pores which are prepared by the surfactant-templating approach. Characterization using XRD, TEM, XPS, H₂ chemisorption, and N₂ sorption techniques reveals that the Pd/OMC catalysts have the ordered 2-D hexagonal mesostructure (space group of p6mm), extremely high surface areas (~1800 m²/g), large pore volumes (~1.64 cm³/g), bimodal pores (6.3 nm of primary mesopores and 1.7 nm of secondary mesopores inside the pore walls), hydrophobic carbon surface, and small metal particles well-dispersed inside the secondary small mesopores. This catalyst exhibits a high yield of 43% for biphenyl from the Ullmann coupling reaction of chlorobenzene in water at 100 °C without assistance of any phase transfer catalyst and can be reused up to 10 times, providing potential opportunities for industrial applications such as coupling and hydrogenation reactions.     

Self-assembly of highly ordered conjugated polymer aggregates with long-range energy transfer

Applications of conjugated polymers (CP) in organic electronic devices such as light-emitting diodes and solar cells depend critically on the nature of electronic energy transport in these materials. Single-molecule spectroscopy has revealed their fundamental properties with molecular detail, and recent reports suggest that energy transport in single CP chains can extend over extraordinarily long distances of up to 75 nm. An important question arises as to whether these characteristics are sustained when CP chains agglomerate into a neat solid. Here, we demonstrate that the electronic energy transport in aggregates composed of tens of polymer chains takes place on a similar distance scale as that in single chains. A recently developed molecular-level understanding of solvent vapour annealing has allowed us to develop a technique to control the CP agglomeration process. Aggregates with volumes of at least 45,000 nm(3) (molecular weight ≈ 21 MDa) maintain a highly ordered morphology and show pronounced fluorescence blinking behaviour, indicative of substantially long-range energy transport. Our findings provide a new lens through which the ordering of single CP chains and the evolution of their morphological and optoelectronic properties can be observed, which will ultimately enable the rational design of improved CP-based devices.     

全钒液流电池用碳纸电极掺氮改性的研究

采用在氨气氛下加热(NCP-600: 600℃下处理, NCP-900: 900℃下处理)对全钒液流电池碳纸电极进行掺氮改性处理。通过此改性处理, 含氮官能团成功地引入到碳纸表面。掺氮处理改善了碳纸表面的亲水性, NCP-900的接触角相比于空白碳纸由120.5°降到99.7°, 且对表面形貌没有明显影响, 不会影响其机械性能。同时, 掺氮处理能明显地增强碳纸的电化学活性, 循环伏安测试中, NCP-900的V(IV)/V(V)电对氧化峰为92.1 mA, 远高于空白碳纸(68.9 mA)。由NCP-900和空白碳纸组装成电池考察了其充放电性能, 在20 mA/cm²下进行充放电, 由NCP-900组装的电池其能量效率为83.73%, 较空白电池高2.59%。掺氮改性处理提高碳纸的电化学性能主要是由于钒电对活性位点的增加和亲水性能的增强。     

Emergent Nonreciprocal Circularly Polarized Emission from an Organic Thin Film

Controlling circularly polarized (CP) emission is key for both fundamental understanding and applications in the field of chiral photonics and electronics. Here, a completely new way to achieve this goal is presented. A luminescent thin film, made from a chiral conjugated phenylene bis-thiophenylpropynone able to self-assemble into ordered structures, emits highly circularly polarized light with opposite handedness from its two opposite faces. Such emergent nonreciprocal behavior in CP emission, so far unprecedented, represents a fundamental advance, opening new opportunities in design, preparation, and applications of CP emitting materials.     

Y-Ba-Cu-O系高温超导相晶体结构的研究

用 Guinier-H(?)gg 多晶衍射数据的 X-射线 Rietveld 方法测定了 Y-Ba-Cu-O 系中正交超导相YBa_2(Cu,Ag)_3O_(9-δ)的晶体结构。多晶衍射图由参数为 a=11.7048(11)(?),b=3.8862(4)(?)及 c=3.8274(6)(?)正交晶胞给出了衍射线指标。最小二乘方修正程序 PIRUM 修正了晶胞参数。结构由平行于 a 轴的三个立方钙钛矿亚胞组成。原子 Y 及 Ba 分别有序地排列在等效点位置(a)及(i)上,由于底面上缺氧,位于相应亚胞上中心的 Cu_1成5配位,形成畸变的四方锥。在 x=1/2轴面短轴上的氧完全空缺,长轴上氧的占有率为1Cu_2为4配位,位于近似矩形的菱面正中心。[CuO_2]~(2-)团平行于(a,c)面无限延伸。按键价理论计算,Cu_1(Ag)上有20%Cu~(3+)存在,Cu_2为2价。     

Steady State Creep Rate Equation of Inconel 718 Superalloy

The steady state creep rate equdtion ofa nickel base superalloy Inconel 718, strengthenedby coherent ordered disc-shaped bct γ~(11) phaseand coherent spherical fcc γ~1 phase precipitates,has been established in the stress and temperatureranges of 620-840 MN m~(-2) and 853-943K, respecti-vely. Constant stress tensile creep tests wereused to medsure the values of steady state creeprate, ε_s, and the consecutive stress reductionmethod was used to measure the back stress duringcreep deformation. The values of effective stressexponent, n_e, were detemined from the slopesof the lgε_s vs. lg(σ_a-σ_0)/G plots. The effectof grain size, d, on steady state creep rdtehas been also studied in this investigation,and the grain size sensitive exponents m weredetemined from the slopes of lgε_s vs. lg(b/d)plots. The creep rate equations of Inconel 718,in the above stress and temperature ranges,have been proposed to beε_s=1.6×10~(-5)(D_1Gb/KT) (b/d )~(0.19)[(σ_a-σ_0)/G]~(1.35)in diffusional creep region, andε_s =75(D_1Gb/KT) (b/d)~(-0.42)[(σ_a-σ_0)/G]~(5.5)in dislocation power law creep region.     

电泳沉积HA -Ti -Y2 O3/ZrO2复合涂层的研究

为了制备均匀致密的HA -Ti -Y2 O3/ZrO2陶瓷涂层,在正丁醇介质中,以三乙醇胺为添加剂,将羟基磷灰石(HA)与Ti,Y2 O3/ZrO2按一定比例混合电泳沉积在钛基底上,得到了形貌稳定的HA -Ti -Y2 O3/ZrO2生物陶瓷涂层.研究了电场强度,电泳时间,添加剂用量对涂层品质的影响.用扫描电镜(SEM)对热处理后的涂层进行了观察,采用红外光谱仪(FTIR)和X射线仪(XRD)对涂层的形貌、组成及结构进行了表征.结果表明:在正丁醇作分散剂,三乙醇胺添加量为12 mL/L,电场强度30～60 V/cm,HA浓度为10～20 g/L,Ti为4～16 g/L,Y2 O3/ZrO2为6～12 g/L的条件下,可制得形貌较好的HA -Ti -Y2 O3/ZrO2复合陶瓷涂层.