Summary: Self-organized honeycomb-patterned polymer films were prepared by using condensed water droplet arrays as templates. Porous polymer masks for dry etching were easily prepared on Si substrates by peeling off the honeycomb-patterned films. After dry etching, hexagonally-arranged micro-pores were formed on the surface of Si substrates. 相似文献
The first catalytic enantioselective Reissert reaction of pyridine derivatives that affords products with excellent regio- and enantioselectivity is described. The key for success is the development of new Lewis acid-Lewis base bifunctional asymmetric catalysts containing an aluminum as a Lewis acid and sulfoxides or phosphine sulfides as a Lewis base. These reactions are useful for the synthesis of a variety of chiral piperidine subunits, and catalytic enantioselective formal synthesis of CP-293,019, a selective D4 receptor antagonist, was achieved. Preliminary mechanistic studies indicated that both sulfoxides and phosphine sulfides can activate TMSCN as a Lewis base. In addition, the sulfoxides with appropriate stereochemistry might stabilize a highly enantioselective bimetallic complex (a presumed active catalyst) through internal coordination to aluminum. 相似文献
In recent years, polymer nanoparticles have been investigated with great interest due to their potential applications in the fields of electronics, photonics, and biotechnology. Here, we report the spontaneous formation of polymer nanoparticles from a clear solution containing a nonvolatile poor solvent by slow evaporation of a volatile good solvent. During evaporation of the good solvent, the solution gradually turns turbid. After evaporation, polymer nanoparticles of homogeneous shape and size are dispersed in the poor solvent. Homogeneous nucleation and successive growth of polymer particles takes place during the dynamic nonequilibrium process of solvent evaporation. The size of the particles, ranging from tens of nanometers to micrometer scale, depends on both polymer concentration and the solvent mixing ratio. Because of the physical generality of the particle formation mechanism, this procedure is applicable to a wide variety of polymers with suitable combinations of solvents. Here, we also show unique features, surface structures and surface properties of polymer nanoparticles prepared by this method. 相似文献
Particles of a poly(para-phenylenevinylene) (PPV) precursor were prepared from an aqueous solution of the polymer by simple evaporation of water from the solution, which also contained an ionic liquid as a poor solvent (self-organized precipitation (SORP) method); PPV precursor nanoparticles were successfully converted to PPV nanoparticles after annealing at 240 degrees C under reduced pressure, this simple process constituting a novel route to nanoparticles of functional polymeric materials. 相似文献
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.
Block copolymer nanopaticles were prepared from the mixture solutions containing good/poor solvents by a simple evaporation process. The block copolymers formed disorder, unidirectionally stacked lamellar, and onion‐like structures in nanoparticles depending on preparation temperatures. Thermal annealing induced the disorder‐order phase transition and order‐order phase transformation in the block copolymer nanoparticles, even though the annealing temperature is lower than the of one polymer segment. The unusual thermal behaviors suggest that the glass transition temperature of the block copolymer is decreased by the effect of nanoparticle, whose surface areas are larger than their volumes.
This Review examines recent developments in the morphological control of polymer microspheres fabricated via the phase separation of polymers as well as the alignment of functional nanoparticles inside microspheres prepared by so‐called bottom‐up synthesis techniques. Several methods for adjusting the internal and surface morphologies of polymer microspheres based on the phase separation of polymer blends and block copolymers are discussed, and the effects of microsphere size on phase separated structures and theoretical simulations of morphologies are also reviewed. The alignment of functional nanoparticles in phase separated polymer microspheres and applications of nanostructured and hybrid polymer microspheres are summarized. 相似文献
Microporous polymer films with a hexagonal arrangement of pores were prepared by simple casting of various polymer solutions under humid conditions. Hexagonally packed micropores were prepared by using condensed water droplets as templates on the surface of polymer solutions. Spherical micro lens arrays (MLAs) were fabricated simply by molding from the resulting honeycomb structures. By peeling off the upper layer with adhesive tape, the pillars were severed, forming pins on each layer, and a hexagonal array of pincushion structures was generated by this procedure. Hemispherical MLAs were also fabricated by molding the pincushion structures. The hemispherical MLAs projected clearer miniaturized images than spherical MLAs. 相似文献
A simple fabrication method is demonstrated for surface‐enhanced Raman scattering (SERS)‐active plasmonic nanoballs, which consisted of Au nanoparticles (NPs) and core–shell polystyrene and amino‐terminated poly(butadiene) particles, by heterocoagulation and Au NP diffusion. The amount of Au NPs introduced into the core–shell particles increases with the concentration of Au NPs added to the aqueous dispersion of the core–shell particles. When the amount of Au NPs increases, closely packed, three‐dimensionally arranged and close‐packed Au NPs arrays are formed in the shells. Strong SERS signals from para‐mercaptophenol adsorbed onto composite particles with multilayered Au NPs arrays are obtained by near‐infrared (NIR) light illumination. 相似文献
Anisotropic polymer meshes, which have micrometre-scale rectangular pores, were prepared by simple stretching and photo-crosslinking of poly(1,2-butadiene) honeycomb films. First, honeycomb films with pores of uniform size were prepared by a simple self-organization process. Then, after stretching and UV photo-crosslinking, anisotropic polymer meshes were formed. These anisotropic polymer meshes had high chemical and thermal stability, and exhibited anisotropic wettability. Moreover, by using a photo-crosslinking process, the anisotropic meshes could be photo-patterned. These anisotropic polymer meshes are expected to be applicable to digital microfluidic devices, cell aligners, and other such devices. 相似文献