Annealing effect on performance and morphology of photovoltaic devices based on poly(3‐hexylthiophene)‐b‐poly(ethylene oxide)

Novel block copolymers, poly(3‐hexylthiophene)‐b‐poly(ethylene oxide) (P3HT‐b‐PEO) were synthesized via Suzuki coupling reaction of P3HT and PEO homopolymers. The copolymers were characterized by NMR, gel permeation chromatography, differential scanning calorimeter, and UV–vis measurements. A series of devices based on the block copolymers with a fullerene derivative were evaluated after thermal or solvent annealing. The device using P3HT‐b‐PEO showed higher efficiency than using P3HT blend after thermal annealing. Phase‐separated structures in the thin films of block copolymer blends were investigated by atomic force microscopy to clarify the relationship between morphologies constructed by annealing and the device performance. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Thermal and pH responsive high molecular weight poly(urethane‐amine) with high urethane content

Aliphatic poly(urethane‐amine) (PUA) was synthesized from copolymerization of CO₂ and 2‐methylaziridine (MAZ) using Y(CCl₃COO)₃‐ZnEt₂‐glycerine coordination catalyst, the urethane content of PUA was over 80%, and its yield could reach 90%. PUA with molecular weight as high as 31.0 kg/mol was obtained when the copolymerization reaction was carried out in N,N‐dimethylacetamide (DMAc), mainly due to the good solubility of PUA in DMAc. PUA exhibited reversible thermo‐responsive property in deionized water, and the lower critical solution temperature (LCST) was highly sensitive to its urethane content and molecular weight, which was observed in a broad window from 37 to 90 °C. Furthermore, the phase transition behavior could also be controlled by change of pH value. When the pH value of the PUA aqueous solution changed from 9.2 to 13, the LCST value of the solution decreased from 48.4 °C to 30 °C. Therefore, the PUA showed thermo‐ and pH‐ dual responsive performance in water. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Peroxidase-like catalytic activity of cubic Pt nanocrystals

Monodispersed cubic platinum (Pt) nanocrystals with an average size of approximately 10 nm were prepared by a reduction method with cetyltrimethylammonium bromide (CTAB) serving as steric stabilizer. The resulting Pt nanocrystals exhibit a peroxidase-like activity and catalyze the H₂O₂-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to produce two colored products with high catalytic activity. The color-generating activity of this system may be influenced by several factors, and we examined several factors to optimize this colorimetric system including buffer types, pH, and concentrations of both H₂O₂ and Pt nanocrystals. The effect of agglomeration of Pt nanocrystals was also investigated, and we find that agglomeration of Pt nanocrystals in aqueous solution distinctly affects Pt nanocrystals catalytic activity. We attribute the catalytic activity of Pt nanocrystals to their acceleration of the electron-transfer process and the consequent facilitation of radical generation.     

Synthesis and Characterization of New Schiff Base and Polyoxa-azaCryptands and Their Rare Earth Cryptates with [1 1] Condensation and Reduction Methods

IntroductionWithspecialandnovelstructures,macropolycyclicmoleculespreselltamultitudeofnewproperties'andopenupvastvistasforapplicationsinmanyfields"',suchassupramoleculardevices,luminescentlabels,fluorescentprobesinbiologicalandmedicalapplications,magneticresonanceimagingandcatalyticcleavageofRNA,and.-theyarealsoimportantligands'forrecognizinginorganicandorganiccanons,anionsandneutralmolecules.Becauseofmulti-stepprocessandlowyields',thesynthesisofmacropolycycliccompoundsaresometimesverydifficu…     

Peptide dendrimer-crosslinked inorganic-organic hybrid supramolecular hydrogel for efficient anti-biofouling

A novel kind of inorganic-organic hybrid supramolecular hydrogel with excellent anti-biofouling capability was developed. The hydrogel was formed via ionic interaction between the negative-charged sodium polyacrylate (SPA) entwined clay nanosheets (CNS) and positive-charged polyhedral oligomeric silsesquioxane (POSS) core-based generation one (L-Arginine) dendrimer (POSS-R).     

Reflection-Absorption Infrared Spectroscopy Study of Polyacrylonitrile on Copper at Elevated Temperature

Reflection-absorption infrared spectroscopy (RAIR) has been used to investigate the chemical structural changes in Polyacrylonitrile (PAN) film adsorbed on copper at 200°C for different time. The formation of an almost fully conjugated C-C=C backbone occurs after heating for only 2 h due to the catalytic effect of copper. The freely dangling cyano groups in PAN molecules initially coordinate to copper surface through the triple bond in π-bonded orientation, then convert to [sgrave]-bonding through the donation of the lone pair of electrons of nitrogen. It is suggested that this transition of the types of coordination would relate to the different geometries of PAN on copper during heating. Since the nitrile complexing and cyclization occur at the same time, the reaction process for the pyrolysis of PAN on copper surface is different from that in the bulk.     

The radio structure of BL Lac object S5 2007+777

BL Lac object S5 2007+777 has been classified as a HYMOR (Hybrid Morphology radio source) for its hybrid FR I and FR II radio morphology. It is one of four BL Lac objects with a kpc scale extended X-ray jet. In this paper, we searched the unpublished European VLBI Network (EVN) archived high resolution data for this source, and present the high resolution radio structure. The EVN images all show a core-jet structure in 1.6, 5 and 8 GHz. In combination with the VLA data in the literature, we found position angle differences (ΔPA) of about 10°–20° between pc and kpc scale jet structures. The brightness temperature estimated from multi-band EVN images are around 10^11.2–10^11.8 K, from which the Doppler factor ranges from 3.2 to 12.0. We found significant flux variations of the radio core in 1.6 and 5 GHz, from which we derived the variability in brightness temperature T _var to be 10^13.6 K and 10^14.0 K, corresponding to the Doppler factors of 9.3 and 12.4, respectively.

     

Preparation and characterization of superfine ammonium perchlorate (AP) crystals through ceramic membrane anti-solvent crystallization

In this paper, a novel ceramic membrane anti-solvent crystallization (CMASC) method was proposed for the safe and rapid preparation ammonium perchlorate (AP) crystals, in which the acetone and ethyl acetate were chosen as solvent and anti-solvent, respectively. Comparing with the conventional liquid anti-solvent crystallization (LASC), CMASC which successfully introduces ceramic membrane with regular pore structure to the LASC as feeding medium, is favorable to control the rate of feeding rate and, therefore, to obtain size and morphology controllable AP. Several kinds of micro-sized AP particles with different morphology were obtained including polyhedral-like, quadrate-like to rod-like. The effect of processing parameters on the crystal size and shape of AP crystals such as volume ratio of anti-solvent to solvent, feeding pressure and crystallization temperature were investigated. It is found that higher volume ratio of anti-solvent to solvent, higher feeding pressure and higher temperature result in smaller particle size. Scaning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the resulting AP crystals. The nucleation and growth kinetic of the resulting AP crystals were also discussed.