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The core–shell polyphenylsilsesquioxane-poly (styrene–butyl acrylate) hybrid latex paticles with polyphenylsilsesquioxane as core and poly (styrene–butyl acrylate) as shell were successfully synthesized by seeded emulsion polymerization using polyphenylsisesquioxane (PPSQ) latex particles as seeds. X-ray diffraction (XRD) indicated that the polyphenylsilsesquioxane (PPSQ) had ladder structure, and PPSQ had incorporated into the hybrid latex particles. Transmission electron microscopy (TEM) confirmed that the resultant hybrid latex particles had the core–shell structure. TEM and dynamic light scattering (DLS) analysis indicated that the polyphenylsisesquioxane latex particles and obtained core–shell hybrid latex particles were uniform and possessed narrow size distributions. X-ray photoelectron spectroscopy (XPS) analysis also indicated that the PPSQ core particles were enwrapped by the polymer shell. In addition, compared with pure poly (styrene–butyl acrylate) latex film, the polyphenylsilsesquioxane-poly (styrene–butyl acrylate) hybrid latex film exhibited lower water uptake, higher pencil hardness and better thermal stability.

A model of thermionic heat engine with the energy selective electron mechanism is studied. Analytical expressions of the power output and efficiency of this device are derived at low temperature, where the chemical potentials of the reservoirs are assumed to be constant. After discussing the impact of the energy spectrum width of the energy selective electron mechanism, we find two bounds ( η ± ) of efficiency at maximum power exist naturally. When the energy spectrum width increases gradually from zero and then to the semi-infinite case with the infinite upper limit, the efficiency at maximum power decreases monotonously from the upper bound η + to the lower bound η − at a given temperature ratio of the cold and hot reservoirs. The two bound are given by numerical simulation and by an analytical expression respectively. These results may provide some guidance for the application of the practical energy selective electron heat engines.

Large-area indium tin oxide (ITO) nanocap arrays are fabricated on porous anodic alumina (PAA) templates to produce robust and cost-effective surface-enhanced Raman scattering (SERS) substrates. The electromagnetic enhancement mechanism is believed to be the main reason for the enhancement. The topography of the ITO nanocap arrays can be adjusted to optimize the enhancement factor by varying the anode voltage applied to the PAA templates. The optical interference in enhanced Raman scattering from the ITO nanocap arrays with different thicknesses are systematically studied and optical self-interference from the incident, scattered, and emitted light is observed to modulate the intensity and shape of the Raman signals.

Diglycidyl ether of bisphenol A (DGEBA)/fluoro-terminated hyperbranched poly(phenylene oxide) (FHPPO) composites with improved mechanical and dielectric performances were prepared by blending a FHPPO with DGEBA. The low-polarity building blocks, abundant fluorinated terminal groups, and the inherent free volume brought by FHPPO efficiently lowered the dielectric constant and the dissipation factor. The free volumes of the cured DGEBA/FHPPO composites, which were quantified by positron annihilation lifetime spectroscopy, increased with the FHPPO loading. The moisture absorption of composites also decreased after the introduction of FHPPO due to the hydrophobicity of fluorinated substituents. Dynamic mechanical analysis tests and scanning electron morphology revealed that FHPPO phase separated from the composites during the curing process. The average diameter of dispersed FHPPO particles increased proportionally with the FHPPO loading. Composites with dispersed particle size of around 150 nm showed the best comprehensive mechanical performance. In addition, incorporation of FHPPO, which has lots of aromatic structures, into DGEBA also increased the thermal stabilities. POLYM. COMPOS., 34:1051-1060, 2013. (c) 2013 Society of Plastics Engineers

A new epoxy-ended hyperbranched polyether (HBPEE) with aromatic skeletons was synthesized through one-step proton transfer polymerization. The structure of HBPEE was confirmed by Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR) measurements. It was proved to be one high efficient modifier in toughening and reinforcing epoxy matrix. In particular, unlike most other hyperbranched modifiers, the glass transition temperature (Tg) was also increased. Compared with the neat DGEBA, the hybrid curing systems showed excellent balanced mechanical properties at 5 wt % HBPEE loading. The great improvements were attributed to the increased cross-linking density, rigid skeletons, and the molecule-scale cavities brought by the reactive HBPEE, which were confirmed by dynamical mechanical analysis (DMA) and thermal mechanical analysis (TMA). Furthermore, because of the reactivity of HBPEE, the hybrids inclined to form a homogenous system after the curing. DMA and scanning electron microscopy (SEM) results revealed that no phase separation occurred in the DGEBA/HBPEE hybrids after the introduction of reactive HBPEE. SEM also confirmed that the addition of HBPEE could enhance the toughness of epoxy materials as evident from fibril formation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1064-1073, 2013

Platinum thin films are deposited on anodic aluminium oxide (AAO) templates by atomic layer deposition (ALD). The highly ordered island-like platinum nanostructures formed on the AAO template produce a high Raman scattering signal because of the periodical hexagonal arrangement. As an illustration, dramatic enhancement is achieved using Rhodamine 6G (R6G) as a molecular probe.Field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) show that the gap between the island-like structures is below 10 nm. Owing to activation by the incident laser beam, the localized electromagnetic field on the platinum island surface can be dramatically enhanced by the sub-10 nm regime subsequently amplifying the Raman signal. Finite-difference time-domain (FDTD) calculation matches the experimental phenomena suggesting that the excellent surface-enhanced Raman scattering (SERS) characteristics of the platinum structure arise from the high density and abundance of hot spots. Because the platinum film is inert in air, the SERS enhancing substrate can be used reliably in many trace chemical and biological detection applications.

Through a novel method, we successfully synthesized electromagnetic (EM) functional polystyrene@polypyrrole@nickel (PS@PPy@Ni) composite microspheres. The PS@PPy spheres with well-defined core/shell structure have been synthesized via an in situ chemical oxidative copolymerization of pyrrole (Py) and N-2-carboxyethylpyrrole (PyCOOH) templated by PS microspheres. The reaction was carried out under heterophase conditions using the mixture of ethanol and water as the continuous phase. Tailored by the carboxyl groups on the surface of microspheres, magnetic nickel layer has been steady deposited onto the P(Py-PyCOOH) layer of the microspheres through an activation-electroless plating technology. The fine PS@P(Py-PyCOOH)@Ni core/shell structures could be obtained with the PyCOOH content up to 50 wt % in the P(Py-PyCOOH) layer. Moreover, the as-prepared PS@P(Py-PyCOOH)@Ni composites are ferromagnetic materials and behave as a good electromagnetic (EM) absorption material due to the coating of Ni layer around the PS@P(Py-PyCOOH) spheres. The PS@P(Py-PyCOOH)@Ni composite spheres show the remarkable EM wave absorption property with the maximum reflection loss (around -20.06 dB) at 10.69 GHz. The EM wave absorption can retained lower than -10 dB within a broad frequency range from 9.16 to 13.75 GHz.

Poly(acrylate-styrene)/poly(acrylate-styrene) core/shell latex particles were synthesized via seeded semi-continuous emulsion polymerization. Both core polymer (CP) and shell polymer (SP) were copolymerized by using three identical monomers of methyl methacrylate (MMA), butyl acrylate (BA) and styrene (St) with different composition ratios. The synthesized core/shell latex particle presents a phase separated state with the interfacial layer between CP and SP. In this study, the weight fractions and the corresponding thickness of this interfacial layer, CP and SP phase in the core/shell latex particle has be successfully calculated by using multi-frequency temperature-modulated differential scanning calorimetry (TOPEM-DSC). The results indicate that the interfacial layer thickness of the core/shell latex particle is determined by the core/shell structure, such as hard core/soft shell (defined as HC/SS) and soft core/hard shell (defined as SC/HS), the glass transition temperature ( T g ) of the “hard” phase (correspondingly core or shell for HC/SS or SC/HS structure, respectively), and the existence of hydrophilic monomer during the copolymerization process such as acrylic acid. Meanwhile, the influence of film-formation-temperature on the microstructure of the latex films was systematically explored in this work.

Submicron-sized Ag-polypyrrole/poly(styrene-co-methacrylic acid) (Ag-PPy/P(St-co-MAA)) composite particles were fabricated via a redox reaction between pyrrole and AgNO3 in the presence of P(St-co-MAA) soap-free latex. The products are characterized by transmission electron microscopy (TEM), electron diffraction spectra (EDS), Raman spectra, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results showed that Ag-PPy nanocomposites were in situ deposited onto the surface of P(St-co-MAA) latex particles tailored by carboxylic-acid groups. The nanocomposites of Ag-PPy distributed on the surface of polymer particles transformed from discretely dots to continuously coating as the reaction temperature increased from 15°C to 60°C. Strawberry-like composite particles were obtained at the reaction temperature of 60°C. The TGA characterization confirmed that the Ag-PPy nanocomposites loading onto the P(St-co-MAA) particles were systematically controlled over a range of 6 wt%–42 wt% by changing the reaction temperatures. The fluorescence quenching effect of the Ag-PPy/P(St-co-MAA) composite particles was explored on Rhodamine B as a model molecule with the Stern-Volmer quenching constant KSV of 5.9 × 104 (g/mL)−1. It is suggested that the fluorescence quenching effect is caused by the resonance energy transfer mechanism.

Here, we synthesized the polystyrene/polysilsesquioxane (PS/PSQ) core/shell latex particles via emulsion polymerization, which behave as an amusing morphology. First, the nanosized PSQ particles were prepared by the hydrolysis-condensation reaction of γ-methacryloxypropyl trimethoxysilane (MPTS) in ethanol medium. Subsequently, the as-obtained methacryloxypropylene functionalized PSQ (PMPTS) sol was directly added into the emulsion system of styrene (St) monomer, and PS/PSQ composite particles with core/shell structure were obtained through emulsion polymerization. We found that the structure of the composite particles can be affected by the synthesis parameters such as reaction time, content of PMPTS added in the reaction, amount of coemulsifier, and the pH value of emulsion system, which were systemically explored by transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis (TGA) in this work. These results indicate that the PMPTS particles in the size of about 5 nm could first absorb onto the surface of PS latex particles so as to assemble in a strawberry-like morphology. The further coalescence among the PMPTS particles would result in a continuous PMPTS shell around the PS core. Moreover, the hollow PSQ capsules were prepared after extraction of the PS core by organic solvent, further confirming the core/shell structure of the as-synthesized PS/PMPTS particles. Meanwhile, we also explored the application of the PS/PSQ core/shell particles as a new kind of Pickering emulsifier in the emulsion polymerization of St, and composite particles with complex patchy morphologies have been obtained finally under different ratios of styrene monomer to PS/PMPTS colloidal emulsifier.

The nucleation of the cationic miniemulsion polymerization of octamethylcyclotetrasiloxane (D4) has been investigated in detail in this work. The particle size was traced by dynamic laser scattering in the polymerization process using different concentration of dodecylbenzenesulfonic acid (DBSA) as both the initiator and surfactant. The results reveal the progressively decreasing particle sizes with the steadily increasing monomer conversion. The descending particle sizes can be explained by the existence of homogeneous nucleation of hydroxyl-terminated polydimethylsiloxane (PDMS) oligomers in addition to the primary droplet nucleation. A linear relationship between the natural logarithm of the average particle diameter (lnd(t)) and the natural logarithm of the monomer conversion (lnf(t)) is then deduced based on the theory, which has been validated by the experimental data. The slope of lnd(t)~lnf(t) line relies on the parameter of K which is the ratio of PDMS oligomers entering water phase to all PDMS oligomers produced. The influence of DBSA concentration on the K and the fraction of homogeneous nucleation (F(H)) has been then obtained. Both of the values of K and F(H) increase with the increasing DBSA concentrations.

A novel fluorine containing epoxy 4-fluoro-4′,4″-diepoxypropoxy triphenyl methane (FDE) was designed and synthesized. The synthesized epoxy was cured by methyl nadic anhydride (MNA) and diglycidyl ether of bisphenol A (DGEBA) was chosen for comparison. Both glass transfer temperature (Tg) and 5% weight loss degradation temperature (Td5%) of cured FDE are over 60°C higher than that of DGEBA. Dielectric constants of the cured FDE at 106 Hz and 107 Hz are 3.09 and 2.91, comparing to 3.50 and 3.24 of the cured DGEBA, respectively. Furthermore, water absorption of the cured FDE is lower than that of DGBEA.

A technique to design and fabricate Au–Ag bimetal microtubes for the investigation of curvature-dependent localized surface plasmon modes is demonstrated. Highly surface-enhanced Raman scattering (SERS) is observed that illustrates the distribution of localized surface plasmon modes leading to an enhanced electromagnetic field. A finite-difference time-domain method is also employed to simulate the electromagnetic field properties on the metal surface. The enhanced SERS performance of such noble bimetal microtubes could spur further interest in the integration of highly sensitive biosensors for rapid, nondestructive, and quantitative bioanalysis, particularly in microfluidics.

Epitaxially grown ultrathin organic semiconductors on graphene show great promise as highly efficient phototransistors. The devices exhibit a strong photoresponse down to the limit of a monolayer organic crystal, with a photoresponsivity higher than 10(4) A W(-1) and a photoconductive gain over 10(8) . The excellent performance is attributed to the high quality of the organic crystal and interface, a unique feature of van der Waals epitaxy.

Non-lithographic template-based approach, especially the porous anodic alumina (PAA) template, owing to its long-range ordering self-assembly hexagonal cells, facile controllability of various configuration shapes, excellent reproducibility, easy fabrication and modest cost, have attracted much attentions these days. Recent research interests of our group are based on this promising template. Several plasmonic nanostructures based on the PAA membranes were successfully fabricated, which were applied to surface-enhanced Raman scattering sensing, the process of tailoring fluorescence as well as surface-enhanced fluorescence cellular imaging. Our recent plasmonic research results based on the PAA membranes and their applications are reviewed here.

In this work, the multiepoxy functional glycidyl ether (GE) modified urea-formaldehyde (UF) resins were synthesized via a traditional alkaline-acid process under low formaldehyde/urea (F/U) molar ratio. The synthesized resins were characterized by 13C magnetic resonance spectroscopy (13C-NMR), indicating that GE can effectively react with UF resins via the ring-opening reaction of epoxy groups. Moreover, the residual epoxy groups of GE could also participate in the curing reaction of UF resins, which was verified by Fourier transform infrared spectroscopy. The storage stability of GE-modified UF resins and the thermal degradation behavior of the synthesized resins were evaluated by using optical microrheology and thermogravimetric analysis, respectively. Meanwhile, the synthesized resins were further employed to prepare the plywood with the veneers glued. For the modification on bonding strength and formaldehyde emission of the plywood, the influences of addition method, type, and amount of GE were systematically investigated. The performance of UF adhesives were remarkably improved by the modification of GE around 20–30% (weight percentage of total urea) in the acidic condensation stage during the resin synthesis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

We demonstrate a convenient nanotechnique to modulate Si–Ag “wire-cap” nanostructures for metal-enhanced fluorescence by self-selective electroless plating on Si. Optimized coupling between Ag caps and organic emitter can be achieved by altering the bending degree of the Si nanowires resulting in significantly enhanced local electric field intensity. The enhanced photoluminescence from the organic emitter coupled Si–Ag “wire-cap” nanostructures derives from the excitation of localized surface plasmons between the Ag nanocaps and also the energy transfer effect in the surface plasmon resonant coupling between the organic emitter and Ag caps. Our technique has potential applications in biochemical sensors and light emitters.

Zn 0.98 Cu 0.02 O powders have been synthesized by microemulsion method. The room temperature ferromagnetism was significantly suppressed, compared with the ZnO powders prepared by the same method. Enhanced room temperature ferromagnetism has been obtained after annealing in H 2 atmosphere at 500 °C for 2 h. The structural characterizations have confirmed the incorporation of the interstitial H and the suppression of the O vacancies. The possibility of the O vacancy mediated room temperature ferromagnetism has been excluded. Our results clearly demonstrated that the observed ferromagnetism originates from the neighboring Cu ions mediated by the interstitial H ions.

Objectives: This study aimed to review etiological and epidemiological data for hand, foot, and mouth disease (HFMD) cases that occurred between 2008 and 2010 in Guangzhou City, to help develop and implement precautionary measures applicable for future outbreaks. Methods: The characteristics of 4,753 HFMD episodes were retrospectively reviewed in 4,636 patients reported between 2008 and 2010 by the Guangdong Women and Children's Hospital, which is the national enterovirus monitoring agent and the designated hospital in China for treating severe HFMD. Results: Out of 4,753 incident episodes reviewed, 525 patients were hospitalized; 60% were males. Most patients (93.8%) were children under 5 years old, with a median age at onset of 2.4 years. HFMD incidence peaked in April/May and September/October. From the total, 1,067 (22.4%) infections were positive for human enterovirus 71 (HEV71), 1,094 (23.0%) were positive for coxsackievirus A16 (CA16), and 941 (19.8%) were positive for other common enteroviruses. In contrast, 1,666 (35.0%) cases were negative to HEV71, CA16, and other common enteroviruses. Cross-correlation coefficients demonstrated associations between the number of cases, seasonal temperatures, and humidity. Among hospitalized cases, HEV71 was positive in 261 (24.5%), and 42 (3.9%) critical cases were positive for HEV71. Conclusion: Seasonal fluctuations and HEV71 and CA16 were the two key factors influencing the Guangzhou HFMD epidemic. The infection predominantly affected children younger than 5 years old. Keywords: Epidemic, Hand, foot and mouth disease, Coxsackie virus A16, Human enterovirus 71

A novel epoxidized hyperbranched poly(phenylene oxide) (EHPPO) is designed and synthesized successfully. The structure of EHPPO is characterized by Fourier transform infrared spectra- and quantitative 13C nuclear magnetic resonance spectrum. The synthesized EHPPO is added into diglycidyl ether of bisphenol A as a modifier in different ratios to form hybrids and cured by an anhydride curing agent. Effects of EHPPO addition on the properties of the cured hybrids are investigated. Thermal mechanical analysis results suggest that addition of EHPPO can increase the free volume of the cured hybrid materials. Dynamic mechanical analysis characterizations show that the crosslinking density increases with the increase in EHPPO content. Furthermore, addition of EHPPO results in an improvement in thermal and mechanical properties. The toughening mechanism is also discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The inorganic–organic trilayer core–shell polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared via seeded emulsion polymerization of acrylate monomers and octamethylcyclotetrasiloxane (D4) gradually, using functional polymethacryloxypropylsilsesquioxane (PSQ) latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of mixed emulsifiers as seeds. The FTIR spectra show that acrylate monomers and D4 are effectively involved in the emulsion copolymerization and formed the polydimethylsiloxane-containing hybrid latex particles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core–shell structure and a narrow size distribution. XPS analysis also indicates that polysilsesquioxane/polyacrylate/polydimethylsiloxane hybrid latex particles have been successfully prepared and PDMS is rich in the surface of the hybrid latex film. Additionally, compared with the hybrid latex film without PDMS, the hybrid latex film containing PDMS shows higher hydrophobicity (water contact angle) and lower water absorption.

Ba doped Bi1.04−xBaxFeO3 ceramics with x up to 0.30 have been prepared by the tartaric acid modified sol–gel method. The X ray diffraction patterns show that the structure transforms from rhombohedral to tetragonal with increasing the Ba substitution concentration from 10% to 30% and the coexistence of distorted rhombohedral and tetragonal phases in 20% Ba substituted BiFeO3, which was further confirmed by the Raman spectra. Bi0.84Ba0.20FeO3 exhibits the highest magnetization (1.6 emu/g under magnetic field of 12 kOe) compared with the other samples of different Ba substitution concentration. Significant enhancement of the ferroelectricity has been observed in 20% and 30% Ba substituted BiFeO3 with saturate polarization close to 6.6 μC/cm2 for Bi0.74Ba0.30FeO3. The magnetoelectric coupling of Bi0.84Ba0.20FeO3 has been measured and the maximum decrease of magnetization under magnetic field of 9.8 kOe was about 0.06 emu/g with increasing applied electric field to 11 kV/cm, and the magnetoelectric coefficient is 1.5×10−12 s/m.

Herein polypyrrole-polystyrene (PPy-PS) hybrid hollow spheres have been prepared by a facile method. In the synthesis, pyrrole was oxidatively polymerized by FeCl3·6H2O in an emulsion of PS latex. The produced PPy deposited onto the surface of the PS particles, which were “dissolved” during the polymerization for the in-situ formation of hollow PPy spheres. The morphology of the hollow spheres was characterized by transmission electron microscope (TEM) and scanning electron microscopy (SEM). The size and size distribution of the hollow spheres were totally depended on that of the PS latex particles which can be adjusted conveniently. The PPy-PS hybrid structure of the shell of the hollow spheres was characterized by selective extraction using tetrahydrofuran (THF) and Fourier transform infrared (FTIR) spectroscopy. The formation process of the hollow spheres was traced by TEM. The probable mechanism for the formation of hollow spheres was also proposed in this work. The influences of the reaction conditions on the formation of the hollow structures have been studied in detail.

Multilayer core–shell poly (styrene-butyl acrylate) latex particles were synthesized via semi-continuous emulsion polymerization, and the process was monitored by a dynamic laser scattering (DLS). The layers of the latex particles were designed to have progressively decreasing glass transition temperatures (Tg) from the core (layer 1) to the outmost shell (layer 4), which was achieved by varying the mass ratio of butyl acrylate (BA) to styrene (St) in the synthesis of each layer. Divinylbenzene (DVB) was added as the crosslinking agent in each layer except for the outmost layer in order to ensure that a continuous film can be formed at room temperature. The damping properties of the formed films as well as the influences of synthesis variables, including the content of DVB added in the internal layers (i.e., layers 1, 2, and 3), the total mass ratio and sequence between layers 3 and 4, and the Tg of each layer were studied by dynamic mechanical analysis (DMA). The results showed that four-layer core–shell latex particles with proper DVB content in each layer exhibited the best damping properties, with a broad effective damping range (tan δ > 0.3) ranging from −12.0 °C to 97.2 °C. The widening of the damping peak can be explained by the formation of a gradient IPN structure in latex particles. Furthermore, the morphology of the formed films was studied by AFM in tapping mode.

Plasmonics is concerned with the interaction between electromagnetic radiation and conduction electrons at metallic/dielectric interfaces and has been a hot research area since 2000. Plasmonics is now attracting more research ac- tivities because a plasmonic nanostructure is one of the most promising candidates to serve as the light scattering and trapping agent to reduce the physical thickness of current solar cells while maintaining the optical thickness. In this pat- ents review, we describe the basic mechanisms of plasmonic thin-film solar cells, summarize the common design and fab- rication techniques, and discuss the future prospects.

Ghost imaging with a classical thermal source is investigated in a two-arm microscope imaging system. The dependence of the imaging visibility on the aperture of the reference lens is discussed. It is shown that by using large apertures, good visibility as well as enhancing resolution can be obtained. The effects from the distance the object is moved away from the original plane are also studied, and one can obtain good visibility with a well-resolved image by changing the distance.

Core–shell polysilsesquioxane-poly(styrene-butyl acrylate-fluorinated acrylate) [PSQ–P(St-BA-FA)] hybrid latex particles were successfully prepared by seeded emulsion polymerization with polymethacryloxypropylsilsesquioxane (PSQ) synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane (MAPTS) in the presence of emulsifiers as seeds. The chemical composition and core–shell morphology of the resultant hybrid particles were investigated by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM), respectively. TEM and dynamic light scattering (DLS) analysis indicated that the core–shell hybrid particles were uniform and possessed narrow size distributions. The surface properties of the latex films produced from the core–shell hybrid particles were also investigated by contact angle (CA) analysis and X-ray photoelectron spectroscopy (XPS) analysis. The results proved the enrichment of fluorine on the film surface, and the latex films had high contact angles and low surface free energies. Optical measurements indicated that the incorporation of fluorinated acrylate onto PSQ particles can effectively reduce light reflectivity of the obtained transparent hybrid latex film. Atom force microscopy (AFM) characterization showed that the obtained hybrid latex film had a smooth surface. Additionally, thermogravimetric analysis (TGA) indicated that the PSQ–P(St-BA-FA) hybrid latex film had better thermal stability than the poly(styrene-butyl acrylate) [P(St-BA)] latex film.

The trilayer core–shell polysilsesquioxane/polyacrylate/poly(fluorinated acrylate) (PSQ/PA/PFA) hybrid latex particles are successfully prepared, using functional PSQ latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of a reactive emulsifier as seeds. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core–shell structure and a narrow size distribution. The Fourier transform infrared (FTIR) spectra show that fluorinated acrylate monomers are effectively involved in the emulsion copolymerization and formed the fluorine-containing hybrid latex particles. XPS analysis of the obtained hybrid latex film reveals that the intensity of fluorine signal in the film–air interface is higher than that in the film–glass interface. In addition, compared with pure polyacrylate latex film, the obtained fluorine-containing hybrid film shows higher hydrophobicity and thermal stability, and lower surface free energy.

The novel and burgeoning technique of surfaced-enhanced cellular fluorescence imaging has tremendous potential in the monitoring and investigation of intracellular processes at the single-molecular level, for instance, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics. The success hinges on the development and fabrication of plasmonic nanostructured surfaces with size and shape compatible with cell interactions because they are crucial to enhanced cellular imaging. In this review, the mechanism of surface-enhanced cellular fluorescence imaging is discussed in view of metal-enhanced fluorescence. The design of nanostructured surfaces with evenly distributed plasmonic fields suitable for enhanced cellular fluorescence imaging such as nanoparticle superlattice coatings, lithographically-based substrates, and alumina-templated surface are described.

We report on a convenient nanotechnique to fabricate large-area silver nanocap superlattice arrays templated by the base of porous anodic alumina membranes as robust and cost-efficient surface-enhanced Raman scattering substrate. The topography can be tuned to optimize the enhancement factor by adjusting anode voltages or the time of silver magnetron sputtering. Our technique is especially promising considering their easy fabrication and evenly distributed plasmonic fields to cm-dimensions featuring high average enhancement factor, thereby boding well for application in the sensing device.

We have investigated the optical properties of poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] containing oxadiazole in backbone (MEH-OPPV) in dilute tetrahydrofuran solution and solid solution films. There is a large dihedral angle between the two adjacent monomer units in MEH-OPPV, which restrains interchain interactions and destroys the conjugation of the polymer to result in blue shifted absorption and emission spectra. The red shifted photoluminescence (PL) peak is continuously changed in the solid solution films with increasing the concentration of MEH-OPPV. Comparison with the dilute solution, an obvious shoulder peak at 465 nm is found in the UV–vis absorption and PL excitation (PLE) spectra of the MEH-OPPV film. The intensity of the PLE shoulder at 465 nm is increased with the concentration of MEH-OPPV in the solid solution films, which is connected with the aggregation of the MEH-OPPV chains. The interchain interactions are restrained and the π-stack aggregates of the polymer chains can not form in the MEH-OPPV due to the large dihedral angle, and then the interchain species are effectively suppressed in the MEH-OPPV films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The excitation energy transfer from poly(N-vinylcarbazole) (PVK) to tris(8-hydroxyquinoline) aluminum (Alq3) in composite films was investigated by adding an inert polymer, poly(methyl methacrylate) (PMMA). The energy transfer efficiency calculated from the photoluminescence (PL) excitation spectra is consistent with that from the time-resolved PL decay data of the composite films. We have found a linear relationship between the two kinds of the distances, which are calculated according to volume density and the Forster theory. Experimental results and analyses provide a facile method to infer the energy transfer efficiency and the distance between the donor and the acceptor molecules in the composite films.

Polymer latex particles were synthesized with multilayer core-shell structure via surface cross-linking emulsion polymerization. The latex core is coated with a five-layer shell. The polymerization was done in a semicontinuous fashion monitored by a dynamic laser scattering (DLS). The copolymer in each layer is designed with alternating high and low glass transition temperature (T(g)). Divinylbenzene (DVB) was added as the cross-linking agent in the synthesis of the "hard" layers to prevent the molecular diffusion from the adjacent "soft" layers. The layer-by-layer increment on the latex core is proved by the alternating changes on the film-formation capabilities of different latex emulsions at room temperature in correspondence with the variance in the T(g) of the outermost polymer layer. The detailed morphologies of the films formed by the latex with different number of layers were characterized by atom force microscopy (AFM). The deformation of the latex particles is largely depended on the nature of the polymer in the outermost layer of the latex particles. Further characterization carried out by multifrequency temperature-modulated differential scanning calorimetry (TOPEM-DSC) confirmed the layer-by-layer structure of the particles, although the molecular redistribution and the interlayer structures were observed. The work provides a routine toward the synthesis of multilayer polymer latexes.

Bi(Fe 1 − x Mn x )O 3 ceramics ( x up to 0.3) were prepared by rapid sintering. Weak ferromagnetism with two magnetic anomalies at low temperatures was observed for Bi(Fe 0.95 Mn 0.05 )O 3 and Bi(Fe 0.9 Mn 0.1 )O 3 . From temperature-dependent magnetic relaxation measurements, the anomalies at 20 K and 100 K are related to the freezing of cluster spin glass.

Surface-enhanced Raman scattering (SERS) coupled with micro- or nanofluidics integrated into optofluidic devices offer many advantages over conventional SERS conducted under static conditions. Higher reproducibility, larger intensity, as well as greater enhancement can be achieved by efficient mixing of analytes and SERS enhancers under a continuous flow. Progress and advances in the past 10 years, including the design of channels and efficient mixing conditions, assemblies of SERS substrates for optimal enhancement, and advantages of optofluidic-SERS analysis, are reviewed. Recent results show that optofluidic-SERS effectively overcomes many of the difficulties and limitations plaguing conventional SERS and the novel technique has enormous application potential.

ZnO/zinc titanate composite materials and pure ZnO have been prepared by sol–gel method. Their structures and photoluminescence properties have been studied. All the samples show a green emission at about 500 nm. The green emission of ZnO/zinc titanate composite materials is greatly enhanced compared with that of pure ZnO. The green emission is assigned to the defects in ZnO. The emission enhancement is due to the increased defects on the effect of formed zinc titanate in the composite materials.

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac)2), and the Cu2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac)2-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac)2 was established. As Cu(Ac)2 which served as the oxidant can also be replaced by AgNO3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu2+ is typical for the existence of Cu(I)–pyrrole coordinate structures with strong Cu(I)–N bond signal shown in XPS characterization.

A kinetic study on the ring-opening polymerization (ROP) of octamethylcyclotetrasiloxane (D4) in miniemulsion is presented in this work. The polymerization is initiated by dodecylbenzenesulfonic acid (DBSA) which also serves as the surfactant (inisurf). The influence of the size of monomer droplet and the concentration of DBSA on the polymerization rate were studied. Since the main place for the ROP of D4 was confirmed to be at the oil/water interface, a three-layer interface model was proposed to analyze the distribution of molecules at the interface and the effects of DBSA. A kinetic equation is then developed based on this model. In the equation, the polymerization rate (Rp) is related to the initial monomer concentration ([D4]0), the droplet radius (r), the coverage of DBSA on monomer droplets surface (x). The polymerization rate can be predicted from the kinetic equation feeding all parameters with their experimental values. Finally, the equation gave a good accordance between the predicted polymerization rate data and the experimental results under different polymerization conditions.

Patterned silver nanocap arrays (PSNAs) prepared on porous anodic alumina templates by a simple coating technique yield enhanced sensitivity and stability in cellular fluorescence imaging. Microstructural analysis, surface-enhanced Raman scattering mapping, and finite difference time domain simulation indicate that the hot spots are evenly distributed on the substrate. Ag1522 or Chinese Hamster Ovary cells are labeled by phalloidin-fluorscein isothiocyanate (P-FITC) on the cytoskeletons and the fluorescence signals from the fluorophores bound on the cell cytoskeletons on the PSNAs are enhanced 8-fold compared to those on glass used in conventional imaging. In addition to the intensity enhancement, the photostability is improved dramatically. Spectral analysis suggests that the PSNAs can create more excitons in the light-emitting P-FITC because of plasmon resonance energy transfer from the silver nanocaps to the nearby P-FITC. They can also act as plasmonic antennae by converting a part of the nonradiative near-field emission from the fluorophores to the far field consequently enhancing the emission.

A light-emitting partially conjugated hyperbranched polymer (2,5-dimethoxy-substituted hyperbranched poly(p-phenylene vinylene), MOHPV) based on rigid fluorescent conjugated segments, 2,5-dimethoxy-substituted distyrylbenzene (a derivative of oligo-poly(p-phenylene vinylene)), and flexible non-conjugated spacers, trioxymethylpropane, was synthesized via an A2 + B3 approach. The weight-average molecular weight was 2.48 × 104 g mol−1. The introduction of two methoxy groups into central rings of the oligo-poly(p-phenylene vinylene) imparted to MOHPV better solubility in common organic solvents and processability than its analogues reported in our previous work, especially the fully conjugated hyperbranched polymers. The effect of the molar ratio of monomer A2 to monomer B3 on the molecular weight and molecular weight distribution was investigated. A single-layer light-emitting diode was fabricated employing MOHPV as an emitter. A double-layer light-emitting diode was also fabricated by doping an electron transport material, 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole, into the emitting layer and inserting a thin layer of tri(8-hydroxyquinoline)aluminium as electron-transporting/hole-blocking layer. A maximum luminance of 1500 cd m−2 at 12 V and a maximum electroluminescence efficiency of 1.38 cd A−1 at 14 mA cm−3, which are approximately 43.5 and 12.9 times greater, respectively, than those of the single-layer device, were achieved. The synthetic simplicity, excellent solubility and solution processability, and less of a propensity to aggregation make MOHPV a novel type of emitter for polymer light-emitting displays. Copyright © 2010 Society of Chemical Industry

La doped BiFeO3, Bi(Fe0.95Co0.05)O3 and Bi(Fe0.95Mn0.05)O3 ceramics have been prepared by sol–gel method with rapid sintering process. X-ray diffraction spectra show that the impurity phase has been effectively suppressed by La doping. The magnetic measurements show that 10% La doping on Bi sites has little influence on the magnetic properties of BiFeO3 and Bi(Fe0.95Co0.05)O3, while significantly enhances the magnetization of Bi(Fe0.95Mn0.05)O3. Raman measurements show larger structure distortion by Co doping or La and Mn codoping on BiFeO3, which explains the significant enhancement of magnetization. Our results suggest that small amount of La doping can be an effective way to prepare high quality BiFeO3 and its derivatives.

The emission of poly(N-vinylcarbazole) nanoparticles, prepared from tetrahydrofuran solution using a reprecipitation method, differed to those of the particles in both solution and film. The photoluminescence spectra of the nanoparticles was broader and red shifted in comparison to those in solution and film. Repulsion between carbazole groups and solvent favours the adoption of a fully overlapped, sandwich-like configuration of neighboring carbazole groups in the nanoparticles. The decay times of the excimers in the nanoparticles were shorter than those in solution.

Ag@polycarbazole as a new 3D nanocomposite material was successfully fabricated using microwave polyol reduction method followed by cations assisted oxidative polymerization of carbazole. The material was characterized by transmission electron microscopes (TEM), scanning electron microscope (SEM), FT-IR, and Raman measurements. The results confirmed that Ag nanoparticles are entirely enclosed by 3,6 polycarbazole. The interfacial study was carried out by X-ray photoelectron spectroscopy, which revealed that Ag surface atoms are intact chemically and blue shifted due to polymer composite formation. The surface plasmon resonance (SPR) and photoluminescence (PL) behavior were found quite sensitive to surface composition of Ag nanoparticles, which is greatly influenced by cations dopant and enclosing polymer in contrary way. The polycarbazole played a contributive role to counterbalance the effect of cations dopant in SPR and PL behaviors along with displaying its luminescence in violet region.

In this study, we present the optical properties of the poly(N-vinylcarbazole) (PVK) films doped with tris(8-hydroxyquinoline) aluminum (Alq3). It has been found that the photoluminescence (PL) spectrum of the PVK film overlaps well with the absorption band of Alq3. When excited at the absorption maximum of PVK, the doped PVK films show enhanced emissions from the Alq3 component. The PL enhancement is considered to be due to energy transfer from PVK to Alq3 in the doped PVK films by analyzing the PL, PL excitation, and time-resolved fluorescence spectra. The energy transfer efficiency is increased with increasing the concentration of Alq3 in the doped PVK film according to time-resolved fluorescence spectra. The energy transfer process has been discussed according to the Forster mechanism. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1772–1777, 2009

A convenient nanotechnique is used to place analyte molecules between closely spaced silver nanorods for investigating surface-enhanced Raman scattering (SERS). The route involves letting absorption of saturated AgNO3 solution in the pores of the porous anodic alumina templates, followed by drying and decomposition of the salt at high temperatures. The silver nanorod arrays boast a high SERS enhancement and large dynamic range. The interrod-coupling-induced enhancement was attributed to the broadening of the plasmon resonance peak because the probability of the resonance covering both the excitation wavelength and the Raman peak increases with its width. The method will be useful in the development of plasmon-based analytical devices, specifically SERS-based biosensors.

The interaction between a hyperbranched polymer and ZnS particles dispersed in water was studied and the multilayer films were layer-by-layered fabricated based on the electrostatic attraction of the hyperbranched polymer and ZnS particles. Finally, the photoluminescence properties of the films were detected. With plenty of characteristic alkalescence amine groups on its backbone, the hyperbranched poly(ester-amine) (HPEA) molecules are water-soluble and self-assemble into micelles in water, and this micellization effect were used to increase the dispersion and stabilization of ZnS particles in water. Meantime, HPEA/ZnS particles could be fabricated into multilayer films based on the mutual strong interaction. The multilayer fabrication process was monitored by UV-vis spectrometer and the surface morphology of the multilayer film was characterized by atom force microscope (AFM). The results showed that with ZnS particles as the outmost layer, the film surface was composed by global particles, and most of them with diameters of about 50 to 100 nm. And when the film was excited by UV light at 244 nm, an emission peak at 495 nm was detected.