Nanometer‐sized polyradical particles: Organic magnetic dot array formed on a silicon microfabricated substrate

A magnetically active, purely organic dot array was formed by the selective deposition of polyradical nanoparticles on array‐like‐formed pits on a silicon substrate. The nanometer‐sized polyradical particles, poly(4‐methacryoyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl), were prepared by the emulsion polymerization of 4‐methacryloyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐acetoxyl followed by a deprotection reaction and oxidation in air. The size (diameter) and radical spin concentration of the polyradical nanoparticles were tunable between the polymerization and oxidation conditions. Electrochemical studies revealed the redox property of the polyradical nanoparticles. The magnetic response image of the polyradical nanoparticles was obtained by magnetic force microscopy, reflecting their radical spin concentrations. These results suggested a possible approach for the use of organic polyradical nanoparticles as organic magnetic dot arrays. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 521–530, 2007     

Interaction between nitric oxide and lipid-like DDPA LB film investigated with SHG and AFM

Interactions between Nitric oxide (NO) and DDPA Langmuir-Blodgett (LB) film are investigated with second harmonic generation (SHG) and atomic force microscopy (AFM). It has been found that the adsorption of NO molecules on DDPA LB film only changes the value of the second-order susceptibility of the DDPA molecule on film but not its orientation.     

Langmuir-Blodgett膜超分子SM/DOPC/Chol三元脂系的原子力显微镜观察

用原子力显微镜研究了胆固醇(Chol)对鞘磷脂(SM)/1,2-二油酸甘油-3-磷脂酰胆碱(DOPC)二元脂系统结构的影响和神经酰胺对SM/DOPC/Chol三元脂系统结构的影响. 实验发现, 在SM/DOPC二元脂系统中, 胆固醇和带饱和脂肪酸链的磷脂发生相互作用形成微区结构, 随着胆固醇含量的增加, 微区的面积逐渐增大, 形成了稳定的片层结构. 当把神经酰胺加入到等摩尔配比的SM/DOPC/Chol三元脂系统中时, 随着神经酰胺比例的增加, 先形成紧密的聚集态结构, 然后逐渐演变成具有特定微区的网状结构. 研究结果表明, 微区的形成主要是由分子不同的官能团之间的相互作用所决定, 这可能在细胞信号传导等生理活动中起到重要的作用.     

Interlocking layer structures formed in spin‐cast polymer blend films by surface segregation and self‐stratification

Surface morphologies formed by the phase segregation of poly(styrene‐b‐ethylene/butylene‐b‐styrene) (SEBS)/poly(methyl methacrylate) (PMMA) blend films prepared via spin coating on mica substrates were studied with atomic force microscopy accompanied by a solvent extraction treatment, X‐ray photoelectron spectroscopy, and contact‐angle measurements. Three kinds of surface structures of films were observed. Besides the ribbonlike morphology and the dispersed domains in a continuous matrix that are common in this field, we found a special interlocking layer structure characterized by a smooth SEBS layer as the cover on the top and a layer composed of hill‐like PMMA dispersed in the SEBS matrix at the bottom when the composition of the film was around 50:50 SEBS and PMMA. A series of blend films with different thicknesses were then prepared to investigate the interfacial structure, and the formation process of the interlocking layer, which could be elucidated by a schematic diagram, was discussed. The interlocking bilayer film with SEBS on the top possessed high thermal stability and the best surface roughness in comparison with other structures. It might find important technical applications in fields such as adhesion, lubrication, and protective coatings. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 532–543, 2007.     

Influence of Film Structure and Precursor Composition on Rhodamine B Retention in Dye-Dopped Ormosils

The interplay between the chemical structure of the precursors, internal organization in the end materials and dye retention was investigated for composites (ormosils) doped with rhodamine B. Besides formulations with triethoxysilanes (RTES) only, we synthesized as well organic–inorganic hybrids with addition of titanium isopropoxide (TIP) and maleic anhydride (MA). The organic (R) functionality of RTES was changed from methyl (MeTES), to phenyl (PTES) and octyl (OTES). Atomic force microscopy and electron microscopy, coupled with thermogravimetric analysis prove that hydrophobicity increase stimulates the transition of film structure: from well-defined, compact particles (for MeTES), to a mixture of porous particles and non-granular material (for MeTES/PTES), with extreme results observed for octyl-based composites. For this latter, the apparent homogeneity comes from cluster-like organization, where the primary entities are pseudo—granules produced by hydrophobic interactions of oligomeric siloxanes. Controlling the composition and gelation procedure resulted in doped composites with good optical transparency and rhodamine B fluorescence emission bands at around 580 nm. Dye transport inside the inorganic structure is not facilitated when: (a) the particles have a compact (nonporous) inner structure and (b) the recipe does not contain the TIP/MA combination. For silica-based films, the dye is located in the macropores (between the granules) of the material and could be easy removed by washing with acetone. On the contrary, using TIP/MA changes not only the internal composition of the granular-like material (by creating a microporous titania-rich outer-shell of the particles) but also the affinity of the Rh-B to permeate and reside inside these new structures.     

Atomic force microscopy investigation of cold‐plasma‐treated poly(ethyleneterephthalate) textiles

Atomic force microscopy (AFM) has been applied to investigate the morphological and topographical surface modifications induced by radiofrequency cold plasma processing of poly(ethyleneterephthalate) textiles. Surface effects are analysed in low‐pressure air plasma for different plasma exposure times. The results show a progressive degradation of the surface with increasing roughness. The analysis suggests that modification of the surface during textile treatment may be ascribed to a plasma‐induced physical process. Copyright © 2003 John Wiley & Sons, Ltd.     

Relaxation dynamics of stretched polymer chains traced by shear induced Shish‐Kebab structure

We have developed a morphologic method to investigate the relaxation processing of the stretched polymer chains in melts, in which an atomic force microscope probe was used to shear the surface of an isotactic polypropylene melt to obtain the isolated shish‐kebab structure. We present the results of the time dependence of length of the isolated shish‐kebab structure and the stress dependence of the kebab density along the direction of shish in this paper. Our results demonstrate that the shear‐oriented polymer melts show the relaxation dynamics of worm‐like chain where the length deficit of the isolated shish‐kebab structure is scaled with the relaxation time as a power of 1/3. The melting behavior of shish‐kebab structure was also investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 907–914     

Atomic Force Microscopy Characterization and Interpretation of Thin‐Film Poly(butylene adipate) Spherulites with Ring Bands

Atomic force microscopy characterization has been conducted to reveal the morphological difference between single‐ring bands in poly(butylene adipate) (PBA). Furthermore, morphological features of the ring‐less Maltese‐cross spherulites are compared to the ring‐band spherulites. Periodic changes in height seem to be common for either the ring‐band or ring‐less (Maltese‐cross) crystal domains; however, the steepness in height change is greater for the ring‐band crystal, while height change in the ring‐less crystal exhibits a terrace‐like layer pattern. In the ring‐band crystal region, the lamellar stalks, which taper off to pointed needle‐like stalks, monotonously protrude out of the layers of softer materials, with no signs of twisting, bending, or turning. In contrast, all lamellae in the ring‐less (Maltese‐cross) crystal region are uniform platelets arranged like flower petals in a layered pattern.

     

DNALB膜的AFM形貌观察

DNA分子本身所具有的独特性质使其在生物学、医学和遗传学等领域占有极其重要的位置 ,近年来 ,人们意识到利用 DNA作为模板剂建造具有特殊结构和功能的纳米材料的可行性 [1] ,如 Braun等 [2 ]将寡聚核苷酸连接在两个金电极之间 ,用 DNA分子作为模板剂生长出 1 2 μm长、直径 1 0 0 nm的银纳米线 ;Mirkin等 [3]将 3 和 5 端连有巯基的寡聚核苷酸与金纳米粒子结合 ,通过互补的碱基形成介观尺寸的组装体 ;Alivisatos等 [4]利用 DNA的特点 ,使其与之相连的金纳米粒子按预计的形式排布形成人造分子 .我们尝试利用 LB技术将 DNA分子复合到…     

Layer‐by‐layer assembly of weak‐strong copolymer polyelectrolytes: A route to morphological control of thin films

Multilayer films were assembled from a strong polyelectrolyte (poly(diallyldimethylammonium chloride), PDADMAC) and a copolymer containing both strongly charged styrene sulfonate moieties and weakly charged maleic acid moieties (poly(4‐styrenesulfonic acid‐co‐maleic acid), PSSMA). Growth of PSSMA/PDADMAC multilayers was linear, as characterized by UV‐vis spectroscopy and quartz crystal microgravimetry. The influence of both the pH of the PSSMA adsorption solutions and the ratio of SS:MA in the PSSMA on multilayer properties was investigated. Fourier transform infrared spectroscopy results showed that the ionization of carboxylic acid groups in PSSMA/PDADMAC multilayers did not vary significantly with changes in the PSSMA assembly pH. However, the multilayers showed different thicknesses, surface morphologies, and stability to post‐assembly pH treatment. We also demonstrate that PSSMA/PDADMAC multilayers are significantly more stable than PSSMA/PAH multilayers after post‐assembly pH treatment (i.e. the films remain intact when exposed to pH extremes). In addition, the surface morphology of two films (PSSMA 1:1 assembled at pH 5.8, post‐treated at pH 2 and PSSMA 3:1 assembled at pH 5.8, post‐treated at pH 11) changed significantly when the films were exposed to solutions of different pH and, in the former case, this change in film morphology was reversible. The porous morphology after treatment at pH 2 could be reversed to give a significantly smoother film after subsequent exposure to water for 24 h. Our results demonstrate that by the rational choice of the assembly pH of PSSMA, stable and pH‐responsive films can be obtained via the sequential assembly of PSSMA and PDADMAC. These films have potential in controlled release applications where film stability and pH‐responsive behavior are essential. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4341‐4351, 2007     

Morphology of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) assemblies in diluted aqueous solution and gel studied by atomic force microscopy

Morphologies of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) (PCL‐PEG‐PCL) triblock copolymer self‐assemblies in the diluted solution and in gel were studied by atomic force microscopy (AFM). The copolymer self‐assembled into wormlike aggregates, of uniform diameter, in water. The wormlike aggregates arranged in order to form separate clusters in the diluted copolymer solution; at a higher copolymer concentration, the clusters became bigger and bigger, and packed together to form gel. Copyright © 2008 John Wiley & Sons, Ltd.     

Triplet harvesting in poly(9‐vinylcarbazole) and poly(9‐(2,3‐epoxypropyl)carbazole) doped with CdSe/ZnS quantum dots encapsulated with 16‐(N‐carbazolyl) hexadecanoic acid ligands

Semiconductor quantum dots (QDs) can be used as alternative for transition metal complexes to harvest the nonemissive triplet excitons in organic light‐emitting diodes (OLEDs). In search for a QD‐based OLED material generating blue emission, poly(9‐vinylcarbazole) (PVK) and poly(9‐(2,3‐epoxypropyl) carbazole) (PEPK) are chosen as host for blue‐emitting CdSe/ZnS core/shell QDs. The QDs are encapsulated with 16‐(N‐carbazolyl) hexadecanoic acid (C16), a ligand terminated by a carbazole moiety. As alternative for PVK, PEPK, where the lower molecular weight and less extensive excimer formation could promise a better film formation and more extensive exciton hopping, is explored. The efficiencies of singlet ( ) and triplet ( ) energy transfer to the C16 capped QDs are estimated by combining stationary photoluminescence spectra and fluorescence decays of pristine polymer films with those of polymer films doped with the QDs. At a loading of 30 wt % of the QDs, increases from 12 ± 1% in PVK to 41 ± 2% in PEPK while increases from 37 ± 22% in PVK to 72 ± 48% in PEPK. The investigation of the film morphology by atomic force microscopy confirms that the main factor limiting the triplet transfer efficiency in the PVK matrix is the clustering of the C16 capped QDs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 539–551     

杯芳烃LB膜修饰电极及其识别性能

为了得到性能好的修饰电极,尝试使用不同的杯芳烃制作LB膜修饰电极,研究了不同空腔大小的和不同上缘取代基的杯芳烃LB膜成膜情况,发现对叔丁基杯芳烃和对烯丙基杯[4]芳烃都可以得到稳定的LB膜,杯环大小可以影响成膜的平均分子占有面积。不同取代基的杯芳烃识别金属铊离子的性能不同,叔丁基基本没有特别的响应,烯丙基有较好的响应,这应归因于电极表面烯丙基对铊离子的吸附或络合作用。     

Studies on the Film Formation of Polysaccharide Based Furan-2-Carboxylic Acid Esters

Furan-2-carboxylic acid esters of xylan, cellulose, curdlan, dextran, and starch were synthesized and studied regarding their film formation abilities. The polysaccharide esters were utilized to prepare films of different appearance. To investigate supermolecular structures of the biopolymer derivatives, atomic force- and scanning electron microscopy were applied. The surface roughness and the macro-pore size and -distribution of the polysaccharide ester films were characterized. Starch furan-2-carboxylic acid ester (starch furoate) did not show film formation. In contrast, dextran furoates are very well suitable for the surface coating of inorganic compounds while the xylan-, cellulose-, and curdlan derivatives yield self-supporting films with different surface characteristics.     

End‐grafting copolymers of styrene and 4‐vinylpyridine on an interacting solid surface

Copolymers of styrene and 4‐vinylpyridine with a styrene fraction f varying from 1 to 0 were grafted onto a silicon substrate in the melt. The grafting reaction and the stability of the grafted chains were investigated by Fourier transform infrared and X‐ray photoelectron spectroscopy. The thickness and surface morphology of the grafted copolymer layers were characterized with ellipsometry and atomic force microscopy (AFM). The copolymer chains were successfully grafted to the surface of the silicon substrate by a reaction between the hydroxyl groups of the nitroxide moiety at the end of the copolymers and the silanol groups on the surface of the silicon wafer. A measurement of the thickness of the grafted copolymer layers showed that the ratio of grafted‐layer thickness to the unperturbed chain radius of gyration decreased with the increasing fraction of 4‐vinylpyridine in the copolymer; this indicated that the grafted layer was strongly attracted to the substrate. In addition, an accelerated grafting process was observed at grafting times ranging from 48 to 72 h for pure poly(4‐vinylpyridine) and copolymers with f values of 0.3 and 0.5. AFM observation revealed that the grafted layers densely and homogeneously covered the silicon substrate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1332‐1343, 2005     

Quantifying phase behavior in partially miscible polystyrene/poly(styrene‐co‐4‐bromostyrene) blends

The phase behavior of thin‐film blends of polystyrene (PS) and the random copolymer poly(styrene‐co‐4‐bromostyrene) (PBS) was studied with atomic force microscopy (AFM) and small‐angle X‐ray scattering (SAXS). Phase behavior was studied as a function of the PBS and PS degree of polymerization (N), degree of miscibility [controlled via the volume fraction of bromine in the copolymer (f)], and annealing conditions. The Flory–Huggins interaction parameter χ was measured directly from SAXS as a function of temperature and scaled with f as χ = f²χ_S–BrS [where χ_S–BrS represents the segmental interaction between PS and the homopolymer poly(4‐bromostyrene)] Simulations based on the Flory–Huggins theory and χ measured from SAXS were used to predict phase diagrams for all the systems studied. The PBS/PS system exhibited upper critical solution temperature behavior. The AFM studies showed that increasing f in PBS led to progressively different morphologies, from flat topography (i.e., one phase) to interconnected structures or islands. In the two‐phase region, the morphology was a strong function of N (due to changes in mobility). A comparison of the estimated PBS volume fractions from the AFM images with the PBS bulk volume fraction in the blend suggested the encapsulation of PBS in PS, supporting the work of previous researchers. Excellent agreement between the phase diagram predictions (based on χ measured by SAXS) and the AFM images was observed. These studies were also consistent with interdiffusion measurements of PBS/PS interfaces (with Rutherford backscattering spectroscopy), which indicated that the interdiffusion coefficient decreased with increasing χ in the one‐phase region and dropped to zero deep inside the two‐phase region. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 255–271, 2002     

Poly(ϵ‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ϵ‐caprolactone) triblock copolymers: Synthesis and self‐assembly in aqueous solutions

Nontoxic and biodegradable poly(?‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(?‐caprolactone) triblock copolymers were synthesized by the solution polymerization of ?‐caprolactone in the presence of poly(ethylene glycol). The chemical structure of the resulting triblock copolymer was characterized with ¹H NMR and gel permeation chromatography. In aqueous solutions of the triblock copolymers, the micellization and sol–gel‐transition behaviors were investigated. The experimental results showed that the unimer‐to‐micelle transition did occur. In a sol–gel‐transition phase diagram obtained by the vial‐tilting method, the boundary curve shifted to the left, and the gel regions expanded with the increasing molecular weight of the poly(?‐caprolactone) block. In addition, the hydrodynamic diameters of the micelles were almost independent of the investigated temperature (25–55 °C). The atomic force microscopy results showed that spherical micelles formed at the copolymer concentration of 2.5 × 10^?4 g/mL, whereas necklace‐like and worm‐like shapes were adopted when the concentration was 0.25 g/mL, which was high enough to form a gel. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 605–613, 2007     

芳香环状低聚体的结构表征

综述了芳香环状低聚体结构表征的发展过程及最新进展,以高效液相色谱、快原子（离子）轰击质谱、激光质谱、电喷雾质谱为主结合其他辅助方法分别做以介绍并比较了各种表征方法的特点及应用范围。     

Stable second‐order NLO semi‐IPN system based on bipyridine‐containing polyimide and alkoxysilane dye

An organosoluble polyimide based on bipyridyl moiety and an alkoxysilane dye have been developed for second‐order non‐linear optics (NLOs). This bipyridine‐containing polyimide exhibits a glass transition temperature of 254°C and a degradation temperature of 400°C. An NLO‐active semi‐interpenetrating network (IPN) system was prepared by blending the polyimide with the alkoxysilane dye via in situ sol‐gel process of alkoxysilane. The selection of this bipyridine‐containing polyimide as the polymeric matrices provides improved solubility and thermal stability, and most importantly enhanced intermolecular interactions. No aggregation of the NLO chromophores in the polyimide matrices was observed through morphology and NLO studies. Under the limitation of chromophore degradation at elevated temperatures, the pristine poled/cured alkoxysilane dye exhibits poorer long‐term stability. By introducing the polyimide upon a silica network by the semi‐IPN system, randomization of the oriented chromophores can be effectively suppressed. Using in situ contact poling, the r₃₃ coefficients of 2.2–17.0 pm/V were obtained for the optically clear semi‐IPN NLO materials. Excellent temporal stability (100°C) was also achieved for these semi‐IPN materials. Copyright © 2005 John Wiley & Sons, Ltd.