Morphological Change of Aggregates of Polystyrene-block-poly (2-vinyl pyridine)/HAuCl4 Complexes in Solution

The self-assembly of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP)/HAuCl₄ complexes in solutions is described. A morphological change from spheres to aggregated spheres, and then to vesicles, all of which contain Au precursor within the micellar corona or vesicle shell, can be prepared from an identical diblock copolymer by controlling the solvent selectivity. The possible mechanisms leading to the morphological transitions are also discussed. This may be a simple, facile route for preparation of a desired gold-containing aggregate.     

两步法制备超疏水性ZnO纳米棒薄膜

采用两步法制备了超疏水性ZnO纳米棒薄膜,在用磁控溅射在普通玻璃衬底上生长一层ZnO籽晶层基础上,利用液相法制备了空间取向高度一致的ZnO纳米棒阵列,经修饰后由亲水性转变为超疏水性.用扫描电子显微镜观察了纳米棒的表面结构,用接触角测量仪测出水滴在ZnO纳米棒薄膜表面的接触角为151°±05°,滚动角为7°.用Cassie模型对ZnO纳米棒薄膜的超疏水性进行了验证.关键词：ZnO纳米棒超疏水两步法     

非对称半结晶两嵌段共聚物的微相分离与结晶行为的模拟退火研究

利用模拟退火方法研究非对称半结晶两嵌段共聚物熔体分别在弱分离和强分离条件下的结晶过程.考察微相分离作用和结晶作用的相对强度对柱状组成的两嵌段共聚物平衡形态的影响.研究结果表明,当嵌段间的相互排斥作用较弱时,结晶便破坏了柱状畴;当此相互作用足够强时,结晶过程可以有效地被限制在熔体微相分离所形成的柱状畴内.另外,介于上述两种情形之间还存在一个模板区域,此时熔体形成的柱状畴大部分被保留下来,但在局部会变形或连通.这些结果和文献报道的实验结果一致.当嵌段间的相互排斥作用非常强时,结晶被抑制,微相分离主导最终形态,观察到了非晶态结构.     

嵌段共聚物受限于软孔内的自组装

利用自洽场方法研究两嵌段共聚物受限于接枝均聚物链(聚合物刷)圆孔中的自组装相形貌.研究表明,当圆孔内径一定时,嵌段比f和聚合物刷C的体积分数φ_C是调控嵌段共聚物相形貌的主要因素,聚合物刷的弹性熵也起着重要作用.当f＝0.7时,在聚合物刷的浸润下,贴近刷表面处AB嵌段共聚物构成环层状结构,随着φ_C的减小这种结构会周而复始地出现.当f处于0.关键词：嵌段共聚物圆孔受限聚合物刷自洽场     

两亲性类树枝状聚合物的合成与药物控释

结合阴离子开环聚合方法合成了内壳为聚(乙氧基乙基缩水甘油醚),外层为聚环氧乙烷的两亲性类树枝状嵌段共聚物PEEGE-G2-b-PEO(OH)₁₂. 使用核磁共振氢谱以及凝胶渗透色谱等表征了中间产物和目标产物. 选择阿霉素作为实验药物,研究了该聚合物的载药和控释行为. 聚合物的载药率和包覆效率分别为13.07%和45.75%,体外释放试验表现为持续性的释放,并受到释放介质pH影响.     

Magnetic nanoparticles separation based on nanostructures

This study describes a magnetic array, which consists of depositing Fe nanowires on a porous alumina membrane. Such a device can be used as a planar magnetic separator. Its performance for the collection of Fe₃O₄ nanoparticles is experimentally shown. For magnetization of such iron nanowires in the vertical direction, we propose equations to calculate the theoretical absorption ratio.     

单甲氧基聚乙二醇-聚(己内酯-co-丙交酯)嵌段共聚物的NMR表征

利用溶液¹³C NMR和HMBC实验对AB型两亲性嵌段共聚物单甲氧基聚乙二醇－聚（己内酯-co-丙交酯）[MeOPEG-P(Cap-co-LL)]的嵌段结构以及聚（己内酯-co-丙交酯）[P(Cap-co-LL)]嵌段中Cap和LL的无规结构进行了表征. 研究发现,P(Cap-co-LL)中Cap、LL的组成对P(Cap-co-LL)的无规度、Cap和LL的酯交换程度以及不同组分的平均链长均有影响. 对LL中立体结构不同所产生的酯交换也进行了表征.     

Phase behaviors in a binary mixture of diblock copolymers confined between two parallel walls

The phase behaviors in a binary mixture of diblock copolymers confined between two parallel walls are investigated by using a cell dynamics simulation of the time-dependent Ginzburg-Landau theory.The morphological dependence of the wall-block interaction and the distance between walls(confinement degree) has been systematically studied,and the effect of repulsive interactions between different monomers is also discussed.It is interesting that multiple novel morphological transitions are observed by changing these factors,and various multilayered sandwich structures are formed in the mixture.Furthermore,the parametric dependence and physical reasons for the microdomain growth and orientational order transitions are discussed.From the simulation,we find that much richer morphologies can form in a binary mixture of diblock copolymers than those in a pure diblock copolymer.Our results provide an insight into the phase behaviors under parallel wall confinement and may provide guidance for experimentalists.This model system can also give a simple way to realize orientational order transition in soft materials through confinement.     

Spherical/gyroid phase diagram of the diblock copolymer in the median selective solvent

The effect of the median selective solution on the lamellar, spherical and gyroid structures is studied. The self-consistent field equations of the diblock copolymer solution are solved by using the reciprocal space method. It is shown that the spherical and gyroid phases have the lowest free energy in the certain range of the solution concentration. Furthermore, the phase diagram of the ordered structures in the diblock copolymer solution with the median selective solvent is calculated, which is consistent with the experimental results. Supported by the National Natural Science Foundation of China (Grant Nos. 10834014, 10674173, and 30770517) and the National Basic Research Program of China (Grant No. 2009CB930704)     

高灵敏银纳米棒阵列对农药啶虫脒的表面增强拉曼散射快速检测

The determination of pesticide residue on agricultural products is increasingly important.Exposure to pesticides can cause severe acute reactions in humans,including aplastic anemia and leukemia.In this work,we developed a rapid and sensitive method to detect acetamiprid pesticide residue based on surface-enhanced Raman scattering.Silver nanorod (AgNR) arrays were fabricated by oblique angle deposition technology and were used as SERS substrates.Prior to detection,the AgNR arrays were cleaned with nitric acid solution or a mixture of methanol and acetone.Compared to the unwashed AgNR arrays,the AgNR arrays washed with methanol and acetone shows a signal enhancement 1000 times greater than the unwashed AgNR array due to the effective removal of the impurities on its surface.The limit of detection of acetamiprid was determined to be 0.05 mg/L.In addition,the molecular structure of acetamiprid was simulated and the corresponding vibration modes of the characteristic bands of acetamiprid were calculated by density function theory.To demonstrate its practical application,the AgNRs array substrates were applied successfully to the rapid identification of acetamiprid residue on a cucumber''s surface.These results confirmed possibility of utilizing the AgNRs SERS substrates as a new method for highly sensitive pesticide residue detection.     

具有阵列-簇双层结构的TiO2纳米棒的光电性能（英文）

选择硫酸氧钛(TiOSO4)作为无机钛源前驱体,通过温和的水热法在掺氟氧化锡导电玻璃基底(FTO)上直接合成单晶金红石相TiO2纳米棒薄膜,呈现阵列-簇双层结构。在模拟太阳光照射下,该纳米棒薄膜的短路电流可达到0.17 mA/cm2,是相同条件下由四异丙醇钛[Ti(iPro)4]为有机钛源而制备的TiO2纳米棒薄膜的2倍多。实验结果表明,多维层状结构和无机硫酸氧根离子(OSO4-4)的存在对TiO2纳米棒薄膜的光电流响应有促进作用。     

Synthesis and Application for Porous Scaffold Materials of Mono-Methoxy Polyethylene Glycol/Polylactide Diblock Copolymer

An amphiphilic diblock copolymer, consisting of mono-methoxy polyethylene glycol (mPEG) and polylactide (PLA), was synthesized by ring-opening polymerization. The chemical structure of the diblock copolymer was verified by means of Fourier transform infrared spectroscopy (FT-IR) and ¹H-NMR, and the weight average molecular weight (M_w ) and polydispersity index (PDI) were measured by gel permeation chromatography (GPC). An mPEG/PLA (20/80) copolymer with a M_w of 4.6 × 10⁴ Da and PDI of 1.39 were obtained when polymerization was conducted at 130°C for 36 h using Sn(Oct)₂ as a catalyst. The compressive strength of an mPEG/PLA scaffold was lower than that of a PLA scaffold; however, the introduction of mPEG into the PLA matrix enhanced its hydrophilicity, and it still meets the requirement of cartilage tissue engineering.     

Ultrafast laser assisted fabrication of ZnO nanorod arrays for photon detection applications

Orderly aligned ZnO nanorod arrays were grown by the ultrafast laser assisted ablation deposition method. These nanorod arrays were further used to make efficient p-n heterojunction photodetector arrays, which have the potential to have nanoscale spatial resolution for imaging, unique incident polarization discrimination capability, and much improved quantum efficiency as well as detection sensitivity. Both front- and back-illumination photodetection schemes were demonstrated by growing those ZnO nanorod arrays on p-type silicon and p-type Zn_0.9Mg_0.1O-coated Al₂O₃ (0 0 0 1) substrates, respectively. Typical diode rectification behavior and photosensitivity were observed in both designs through I-V and photocurrent measurements.     

Photovoltaic properties of the copper-phthalocyanine and ZnO nanorod array system affected by ethanol

Well-aligned ZnO nanorod array, fabricated on conductive indium-tin-oxide (ITO) substrate by wet chemical bath deposition (CBD) method, was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Surface photovoltage (SPV) technique was employed to study the photovoltaic properties of the copper-phthalocyanine (CuPc) and ZnO nanorod array system affected by ethanol. Prior to ethanol adsorption, two pronounced SPV response bands were exhibited for this system in the range 300-410 and 540-760 nm, respectively. Post-adsorption measurements reveal that the SPV intensity of the former band is enhanced, while that of the latter band is suppressed if ethanol was used to modify CuPc surface. Moreover, both of the SPV intensity of two response bands is enhanced if ethanol was used to modify ZnO and CuPc interface. Mechanisms of these phenomena were suggested.     

Ring pattern solutions of a free boundary problem in diblock copolymer morphology

The cross section of a diblock copolymer in the cylindrical phase is made up of a large number of microdomains of small discs with high concentration of the minority monomers. Often several ring like microdomains appear among the discs. We show that a ring like structure may exist as a stable solution of a free boundary problem derived from the Ohta-Kawasaki theory of diblock copolymers. The existence of such a stable, single ring structure explains why rings exist for a long period of time before they eventually disappear or become discs in a diblock copolymer. A variant of Lyapunov-Schmidt reduction process is carried out that rigorously reduces the free boundary problem to a finite-dimensional problem. The finite-dimensional problem is solved numerically. A stability criterion on the parameters determines whether the ring solution is stable.