Novel glucosamine hydrochloride functionalized water‐soluble conjugated polyfluorene was easily synthesized through Cu(I)‐catalyzed azide/alkyne “click” ligation and Suzuki coupling polymerization. The water‐solubility and biocompatibility of the polymer were improved after grafting glucosamine hydrochloride to the side chains of the conjugated polymer. As a fluorescent model system of chitosan, its interaction with single‐stranded DNA was studied by spectrofluorometric titration.
This study reports a continuous prepartion of spherical or hemispherical polymer particles simply utilizing the phase separation in polymer blend films during the coating process. We took an advantage of the strong phase separation between a water‐soluble crystalline polymer as a matrix and hydrophobic polymers as minor components. We demonstrated the prepartion of water‐soluble polystyrene (PS) particles, nitrilotriacetic acid (NTA)‐functionalized PS particles for protein separation, and semiconducting poly(3‐hexylthiophene) (P3HT) particles. The sizes of the particles could be controlled by adjusting the film thickness and weight fraction of the minor component polymers in the blend film. It provides a simple facile way to prepare polymer particles in a continous process.
We report here a facile synthesis of high performance electro‐active polymer actuator based on a sulfonated polyimide with well‐defined silver electrodes via self‐metallization. The proposed method greatly reduces fabrication time and cost, and obviates a cation exchange process required in the fabrication of ionic polymer‐metal composite actuators. Also, the self‐metallized silver electrodes exhibit outstanding metal‐polymer adhesion with high conductivity, resulting in substantially larger tip displacements compared with Nafion‐based actuators.
The lithium salt of 2,6‐difluoro‐2′‐sulfobenzophenone was conveniently synthesized in one‐pot by reacting 2,6‐difluorophenyllithium with 2‐sulfobenzoic acid cyclic anhydride in THF at −70 °C whereafter the product crystallized out of solution. A poly(arylene ether) and a poly(arylene sulfide) were prepared by polycondensation reactions to demonstrate the reactivity and efficacy of this new monomer to produce sulfonated high‐molecular weight aromatic polymers for fuel cell proton‐exchange membranes. This work demonstrated that organolithium chemistry may offer versatile and straightforward pathways to new functional monomers with fluorine atoms activated for nucleophilic aromatic substitution reactions.
Microporous films consisting of two‐dimensionally ordered void structures ‐ so‐called honeycomb films ‐ were produced by evaporation of polymer solutions under high humidity. Two types of poly(vinyl cinnamate)s were used: A newly synthesized amphiphilic poly(vinyl cinnamate) and a mixture of a commercial poly(vinyl cinnamate) and an amphiphilic polyion complex. Photo‐crosslinking of the honeycomb structure could be achieved by UV irradiation while completely retaining the film morphology. The crosslinked films showed excellent stability against organic solvents.
Summary: A novel kind of dendronized porphyrin polymers was synthesized by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized macromonomers bearing Fréchet‐type dendrons. The encapsulation of red‐light‐emitting porphyrin‐containing conjugated backbones into dendronized polymers can not only reduce the aggregation of polymer backbones and the self‐quenching of their fluorescence but also endow the porphyrin polymers with good solubility. We also report the optical and electrochemical properties of the porphyrin‐containing dendronized polymers.
Synthesis of a novel kind of dendronized porphyrin polymers by Sonogashira coupling of diethynyl‐functionalized porphyrin monomers and diiodo‐functionalized dendritic macromonomers. 相似文献
Reactions between the ethylene groups in the backbone of conjugated polymers under UV illumination and heat treatment result in the cross‐linking of the main polymer chains. The cross‐linking leads to two simultaneous results in the polymer: excellent solvent resistance and increased bandgap. Using this reaction, three‐color polymer light‐emitting diodes (PLEDs) with a multi‐layer structure can be easily realized by a dry photo‐pattern in an active‐gas‐free environment. Multi‐layer blue devices with dramatically enhanced efficiency can also be achieved conveniently.
A new general approach for rapid performance‐screening of polymer compositions is provided. Multiple compositions are generated as one‐dimensional libraries in a microextruder with step‐ or gradient‐composition changes in 2–10 g of polymer in < 1 min. To accelerate testing, environmental stress is applied to only local regions, followed by high‐sensitivity spatially resolved characterization. We applied our methodology for weathering of arrays of polymeric compositions and provided ranking of polymer/UV absorber compositions equivalent to traditional weathering data while achieved 20 times faster.
Sampling and measurement strategies for HT analysis of combinatorial 1D polymeric libraries: (1) spectroscopic monitoring of chemical properties, (2) in‐situ monitoring of mass and viscoelastic properties, (3) scanning spectroscopic analysis, and (4) spectroscopic imaging of a coiled polymeric array. 相似文献
In this work, the process of spin dewetting of a polymer solution on a topographically patterned PDMS mold was used for fabrication of micro‐ and nanaoscale polymer structures. Spin coating was used to provide a fast and reproducible coating. This simple technique was capable of producing a wide range of polymer feature geometries from a single microfabricated mold. This experimental study looks at the effects of the original mold feature geometry as well as the polymer solution concentration on the resultant microstructures. Polystyrene and poly(propyl methacrylate) were used as model polymers. Features with film thickness ranging from <100 nm to >5 µm were obtained using this technique. The process was also extended to fabrication of nanoscale features.
Summary: Polystyrene (PS) micro‐ and nanospheres with uniform dimensions and smooth surfaces have been produced by electrospray. The effect of PS molecular weight on beads morphology and the fundamental role of concentration have been investigated. Moreover, a new apparatus was designed to collect the polymer spheres during the process and to prevent the coalescence among the spheres.
PS micro‐ and nanospheres produced by electrospray 相似文献
A direct access to photochromic polymeric vesicles was demonstrated via polymerization‐induced self‐assembly and reorganization (PISR). The resulting vesicles displayed interesting photochromic behaviors different from that of their free polymer chains in DMF, and the vesicles exhibited stronger fluorescence and excellent photostability due to confinement of conformational flexibility of the polymer chains in aggregates.
Au nanoparticles (NPs) and polymer composite particles with phase‐separation structures were prepared based on phase separation structures. Au NPs were successfully synthesized in amphiphilic block‐copolymer micelles, and then composite particles were formed by a simple solvent evaporation process from Au NPs and polymer solution. The phase separated structures (Janus and Core‐shell) were controlled by changing the combination of polymers having differing hydrophobicity.
Summary: Fabrication of honeycomb‐patterned films from amphiphilic dendronized block copolymer (PEO113‐b‐PDMA82) by ‘on‐solid surface spreading’ and ‘on‐water spreading’ method is reported. Highly ordered honeycomb films with quasi‐horizontally paralleled double‐layered structure can be fabricated by the on‐solid surface spreading method. This work raises the possibility that such structures can be formed in amphiphilic dendronized block copolymers and extends the family of source materials.
Summary: Phosphonate groups were introduced into block copolymers of styrene derivatives either as single end‐groups or as small blocks using nitroxide‐mediated radical polymerization. In order to combine the hydrophobic and hydrophilic segments, block copolymers with N,N‐dimethyl acrylamide were synthesized. After hydrolysis to phosphonic acid groups, adsorption of the polymer onto metal oxides was possible.
Conversion of the phosphonate groups by transesterification with trimethylbromosilane (TMBS), followed by hydrolysis of the silylester group. 相似文献
Soft nanotechnology requires new approaches and materials to efficiently convert chemical energy into mechanical motion and vice versa. A number of key design parameters, such as responsiveness to external stimuli, directionality of response through alignment, transduction via surface stresses or changes in ionic conductivity can be found in polymer brushes and several recent examples of actuation and transduction in polymer brushes will be explored.
Here, we report the use of fluorescently labelled proteins to study protein adsorption to microarrayed synthetic polymers for the first time, indicating that this method is appropriate for the study of protein adsorption on these arrays. To investigate protein adhesion directly we use atomic force microscopy (AFM) to measure the force of adhesion between a protein‐coated probe and the arrayed polymers. Both approaches show promise as methods for screening protein interactions with polymers in a microarray format. Comparison of these very different measures of protein–surface interactions indicate a good correlation.
This study reports a spontaneous selective localization of molecules in crosslinked particles during electrospraying and electrospinning polymer solutions containing the particles. It provides a facile way of preparing microcapsules and fibers with controlled release. The dye molecules were phase separated from the crystalline polymer matrix during the electrohydrodynamic process and moved to the solvent‐rich crosslinked particles. The position of the particles in the microcapsules and fibers could be controlled by adjusting compatibility of the particles with the matrix polymer. The microcapsules and fibers did not show the initial burst release of the molecules and gave considerably prolonged release behavior.
Equilibrium P–V–T properties of randomly crosslinked amorphous polymer networks are modeled via molecular dynamics simulation for connectivity ratios between 1.0 and 1.5. The relation between connectivity ratio and network shrinkage is studied over a wide range of temperatures and pressures. The simulation results are compared to a mean‐field Flory–Huggins lattice model.
The pulsed‐laser polymerization technique is used to determine the composition‐averaged free‐radical propagation rate coefficient (kp,ter) for terpolymerization of butyl methacrylate, butyl acrylate, and styrene between 60 and 120 °C. A significant deviation from terminal model predictions is observed for the ternary system, indicating that penultimate kinetics are important at these industrially relevant temperatures. The implicit penultimate propagation model, with all the coefficients taken from previous studies of the binary systems, provides a good prediction of the experimental kp,ter results.
