Integrated processing-structure-property analysis on rubber in-mold vulcanization

On the basis of the quantitative relationship among rubber processing, structure and property, the methodology of the integrated processing-structure-property analysis on rubber in-mold vulcanization is presented, and then the temporal evolution and spatial distribution characteristics of silicone rubber hot processing parameters, crosslinking structure parameters and mechanical property parameters are obtained by means of the finite element method. The present work is helpful for optimizing curing conditions, and then the design of rubber vulcanization processes according to certain requirements can be done.

Investigation of the dewetting inhibition mechanism of thin polymer films

The mechanism of inhibition of polymer film dewetting is investigated by adding a star comb-like polymer, four-arm P(S-ran-VB-g-PMMA), to PS film and PMMA film on different substrates. It is found that the mechanism of inhibition of polymer film dewetting is kinetic in nature, and is related to the miscibility between the additional compound and the polymer film. On addition to the miscible system [four-arm P(S-ran-VB-g-PMMA) and PMMA], the star comb-like polymers can increase the resistant force of dewetting with hole growth and inhibit the dewetting process of the thin polymer film by enrichment in the rim.

Microphase Separation of Mixed Polymer Brushes: Dependence of the Morphology on Grafting Density, Composition, Chain-Length Asymmetry, Solvent Quality, and Selectivity

Microphase separation of binary mixed A/B polymer brushes exposed to different solvents is studied using Single-Chain-in-Mean-Field simulations. Effects of solvent quality and selectivity, grafting density, composition, and chain-length asymmetry are systematically investigated, and diagrams of morphologies in various solvents are constructed as a function of grafting density and composition or chain-length asymmetry. The structure of the microphase segregated morphologies lacks long-range periodic order, and it is analyzed quantitatively Using Minkowski measures.

White Electroluminescence from a Phosphonate-Functionalized Single-Polymer System with Electron-Trapping Effect

A novel strategy for obtaining white electroluminescence (EL) is based on the mechanism of electron trapping on host. Phosphonate-functionalized polyfluorene is chosen as host owing to its strong electron affinity. Electrons are confined mostly by host pendants in the EL process, which suppresses charge transfer from host to dopant. White EL with CIE coordinates of (0.34,0.35) is achieved.

Blends based on sulfonated poly[bis(benzimidazobenzisoquinolinones)] and poly(vinylidene fluoride) for polymer electrolyte membrane fuel cell

A new blend system consisting of an amorphous sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI) and the semi-crystalline poly(vinylidene fluoride) (PVDF) was prepared for proton exchange membranes. The miscibility behavior of a series of blends of SPBIBI with PVDF at various weight ratios was studied by WXRD, DSC and FTIR. The properties of the blend membranes were investigated, and it was found that the introduction of PVDF in the SPBIBI matrix altered the morphological structure of the blend membranes, which led to the formation of improved connectivity channels. For instance, the conductivity of the blend membrane containing 10 wt% PVDF displayed the highest proton conductivity (i.e., 0.086 S cm(-1)) at room temperature, a value almost twofold that of the pristine SPBIBI membranes (i.e., 0.054S cm(-1)) under identical conditions.

Poly[[diaqua-mu-4,4 '-bipyridine-dinitratodi-mu-L-tyrosinato-dicopper(II)]: a chiral two-dimensional coordination polymer

The title compound, [Cu-2(C9H10NO3)(2)(NO3)(2)(C10H8N2)-(H2O)(2)](n), contains Cu-II atoms and L-tyrosinate (L-tyr) and 4,4'-bipyridine (4,4'-bipy) ligands in a 2:2:1 ratio. Each Cu atom is coordinated by one amino N atom and two carboxylate O atoms from two L-tyr ligands, one N atom from a 4,4'-bipy ligand, a monodentate nitrate ion and a water molecule in an elongated octahedral geometry. Adjacent Cu atoms are bridged by the bidentate carboxylate groups into a chain. These chains are further linked by the bridging 4,4'-bipy ligands, forming an undulated chiral two-dimensional sheet. O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds connect the sheets in the [100] direction. This study offers useful information for the engineering of chiral coordination polymers with amino acids and 4,4'-bipy ligands by considering the ratios of the metal ion and organic components.

Flourescent Switch Constructed Based on Hemin-Sensitive Anionic Conjugated Polymer and Its Applications in DNA-Related Sensors

Here, a fluorescent switch is constructed combining hemin, hemin aptamer, and a newly synthesized anionic conjugated polymer (ACP), poly(9,9-bis(6'-phosphate-hexyl) fluorenealt-1,4-phenylene) sodium salt (PFHPNa/PFP). In the "off-state", the fluorescence of PFP is sensitively quenched by hemin, with a high K-sv value of similar to 10(7). While in the "on-state", the formation of the aptamer/hemin complex recovers the fluorescence intensity. The fluorescent switch is sensitive and selective to hemin. To testify the universality and practicality of the fluorescent switch, a series of label-free DNA-related sensing platforms are developed, containing three DNA sensing strategies and one ATP recognition strategy. The fluorescent switch developed is simple, sensitive, and universal, which extends applications of the anionic conjugated polymers.

Perfectly Hydrophobic Silicone Nanofiber Coatings: Preparation from Methyltrialkoxysilanes and Use as Water-Collecting Substrate

Perfectly hydrophobic (PHO) coatings consisting of silicone nanofibers have been obtained via a solution process using methyltrialkoxysilanes as precursors. On the basis of thermal gravimetry and differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FTIR) results, the formula of the nanofibers was tentatively given and a possible growth mechanism of the nanofibers was proposed. Because of the low affinity between the coatings and the small water droplet, when using these coatings as substrate for collecting water vapor, the harvesting efficiency could be enhanced as compared with those from bare glass substrate for more than 50% under 25 degrees C and 60-90% relative humidity. By removing the surface methyl group by heat treatment or ultraviolet (UV) irradiation, the as-prepared perfectly hydrophobic surface can be converted into a superhydrophilic surface.

Enhanced charge collection in polymer photovoltaic cells by using an ethanol-soluble conjugated polyfluorene as cathode buffer layer

We report enhanced polymer photovoltaic (PV) cells by utilizing ethanol-soluble conjugated poly (9, 9-bis (6'-diethoxylphosphorylhexyl) fluorene) (PF-EP) as a buffer layer between the active layer consisting of poly(3-hexylthiophene)/[6, 6]-phenyl C61-butyric acid methyl ester blend and the Al cathode. Compared to the control PV cell with Al cathode, the introduction of PF-EP effectively increases the shunt resistance and improves the photo-generated charge collection since the slightly thicker semi-conducting PF-EP layer may restrain the penetration of Al atoms into the active layer that may result in increased leakage current and quench photo-generated excitons. The power conversion efficiency is increased ca. 8% compared to the post-annealed cell with Al cathode.

Controlled phase separation for efficient energy conversion in dye/polymer blend bulk heterojunction photovoltaic cells

Low-cost photovoltaic energy conversion using conjugated polymers has achieved great improvement due to the invention of organic bulk heterojunction. in which the nanoscale phase separation of electron donor and acceptor favors realizing efficient charge separation and collection. We investigated the polymer photovoltaic cells using N, N'-bis(1-ethylpropyl)-3,4,9,10-perylene bis(tetracarboxyl diimide)/poly(3-hexyl thiophene) blend as an active layer. It is found that processing conditions for the blend films have major effects on its morphology and hence the energy conversion efficiency of the resulting devices. By optimizing the processing conditions, the sizes of donor/acceptor phase separation can be adjusted for realizing efficient charge separation and collection. The overall energy conversion efficiency of the photovoltaic cell processed with optimized conditions increases by nearly 40% compared to the normally spin-coated and annealed cell.

Efficient tandem polymer photovoltaic cells with two subcells in parallel connection

Tandem polymer photovoltaic cells with the subcells having different absorption characteristics in series connection are widely investigated to enhance absorption coverage over the solar spectrum. Herein. we demonstrate efficient tandem polymer photovoltaic cells with the two stacked subcells comprising different band-gap conjugated polymer and fullerene derivative bulk heterojunction in parallel connection. A semitransparent metal layer combined with inorganic semiconductor compounds is utilized as the intermediate electrode of the two stacked subcells to create the required built-in potential for collecting photo-generated charges. The short-circuit current of the stacked cell is the sum of the subcells and the open-circuit voltage is similar to the subcells.

Performance Enhancement of Polymer Light-Emitting Diodes by Using Ultrathin Fluorinated Polyimide Modifying the Surface of Poly(3,4-ethylene dioxythiophene):Poly(styrenesulfonate)

Herein, an insulating fluorinated polyimide (F-PI) is utilized as an ultrathin buffer layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in polymer light-emitting diodes to enhance the device performance. The selective solubility of F-PI in common solvents avoids typical intermixing interfacial problems during the sequential multilayer spin-coating process. Compared to the control device, the F-PI modification causes the luminous and power efficiencies of the devices to be increased by a factor of 1.1 and 4.7, respectively, along with almost 3-fold device lifetime enhancement. Photovoltaic measurement, single-hole devices, and X-ray photoelectron spectroscopy, are utilized to investigate the underlying, mechanisms, and it is found that the hole injection barrier is lowered owing to the interactions between the PEDOT:PSS and F-PI. The F-PI modified PEDOT:PSS layer demonstrates step-up ionization potential profiles from the intrinsic bulk PEDOT:PSS side toward the F-PI-modified PEDOT:PSS surface, which facilitate the hole injection.

Effect of Poly (3-hexylthiophene) Nanofibrils on Charge Separation and Transport in Polymer Bulk Heterojunction Photovoltaic Cells

Crystalline poly (3-hexylthiophene) (P3HT) nanofibrils are introduced into the P3HT: [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) composite films via P3HT preaggregation in solution by adding a small amount of acetone, and the correlation of P3HT nanofibrils and the optoelectronic properties of P3HT:PCBM bulk heterojunction photovoltaic cells is investigated. It is found that the optical absorption and the hole transport or the resulted P3HT:PCBM composite films increase with the increase of the amount of P3HT nanofibrils due to the increased P3HT crystallinity and highly interconnected nanofibrillar P3HT networks. However, it is also found that high contents of crystalline P3HT nanofibrils may restrain PCBM molecules from demixing with the P3HT component that forms electron traps in the active layer. and hence reduce the charge collection efficiency. Small contents of P3HT nanofibrils not only improve the demixing between P3HT and PCBM components, but also enhance the hole transport via crystalline P3HT nanofibrillar networks, resulting in efficient charge collection.

Formation of low surface energy separators with undercut structures via a full-solution process and its application in inkjet printed matrix of polymer light-emitting diodes

In this paper, low surface energy separators With undercut structures were fabricated through a full solution process, These low Surface energy separators are more suitable for application in inkjet printed passive-matrix displays of polymer light-emitting diodes. A patterned PS film was formed on the P4VP/photoresist film by microtransfer printing firstly. Patterned Au-coated Ni film was formed on the uncovered P4VP/photoresist film by electroless deposition. This metal film was used as mask to pattern the photoresist layer and form undercut structures with the patterned photoresist layer. The surface energy of the metal film also decreased dramatically from 84.6 mj/m(2) to 21.1 mJ/m(2) by modification of fluorinated mercaptan self-assemble monolayer on Au surface. The low surface energy separators were used to confine the flow of inkjet printed PFO solution and improve the patterning resolution of inkjet printing successfully. Separated PFO stripes, complement with the pattern of the separators, formed through inkjet printing.

ZnO Nanorods as Scatterers for Random Lasing Emission from Dye Doped Polymer Films

A random lasing emission from 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polystyrene (PS) thin films was realized by the scattering role of ZnO nanorods. The device was fabricated by spin-coating DCJTB doped PS on ZnO nanorods. The ZnO nanorods were grown on indium-tin-oxide (ITO) glass substrate by hydrothermal synthesis method. It can be seen that the device emits a resonance multimode peak at center wavelength of 630 nm with a mode line-width of less than 0.23 nm and exhibits threshold excitation intensity as low as 0.375 mJ pulse(-1) cm(-2). The agreement of the dependence of threshold pumped intensity on the excitation area with the random laser theory indicates that the lasing emission realized here is random laser. Our results demonstrate that the nanostructured ZnO nanorods are promising candidate as alternative sources of coherent light emission to realize organic lasers.