Chiral polyethyne derivatives with lyotropic liquid‐crystalline properties are found to be able to self‐assemble, forming two chiral organizations with opposite handedness in solid thin films by selection of the casting solvent and its concentration. After the film preparation, chiral organization could also be induced by simple exposure to an appropriate organic solvent's vapor for several minutes without thermal treatment. Furthermore, irreversible inversion of the handedness of the chiral organization in the film could be achieved by exposure to solvent vapor.
The self‐assembly of two types of linear ABA triblock copolymers confined in cylindrical nanopores is studied using simulated annealing. The effects of pore size and block copolymer chain architecture on morphology, chain conformations and bridging fraction are investigated. For the bulk cylinder‐forming copolymers, novel structures such as helices and stacked toroids form, which depend sensitively on the pore size. Several significant differences between the two types of copolymers are predicted and explained based on the differences in their chain conformations and chain architectures. A simple model is proposed to explain the mean square radius of gyration for the bridge and loop chains.
Summary: Magnetic nanoparticles have been prepared by a co‐precipitation method and modified with methacryloxypropyltrimethoxysilane. Magnetic molecularly imprinted polymer particles have been prepared by suspension polymerization in silicone oil. The particles possess a high affinity to the template molecules and are rapidly separated under a magnetic field.
Recently, it has been recognized the shape of particles plays an essential role in the design of materials with unique properties. In this study, PLGA non‐spherical microarchitectures, rods and fibers, were fabricated successfully in high yield by single emulsion‐solvent evaporation method in the presence of sodium tripolyphosphate. The assay of PVA residue was carried out and the hydrogen bonds formation was verified as well. The presented data show that viscosity and coagulation agent have a synergistic effect on forming the rod‐ and fiber‐like microarchitectures in the shear response and the formation mechanisms were proposed accordingly.
Summary: A chiral, regioregular poly[3‐(4‐alkoxyphenyl)thiophene] has been prepared and studied. Films prepared by fast evaporation of the solvent, consist of random‐coils, while films prepared by slow evaporation are composed of chirally aggregated, coplanar strands. Heat treatment transforms the random‐coils into aggregated films via an intermediate state, which was characterized as chiral, coplanar, unaggregated polymer strands.
Overview of the possible aggregation processes. 相似文献
A simple method using water‐soluble conjugated polymers and a DNA intercalator has been proposed for single base pair mismatch detection with enhanced detection efficiency. Fluorescence resonance energy transfer (FRET) was used as an indicator for unwinding of dsDNA due to base pair mismatch at elevated temperatures. The optical amplification effect of the CPs helps to achieve enhanced detection efficiency.
π‐Conjugated microporous networks have been prepared from the tetraarylated diketopyrrolo[3,4‐c]pyrrole unit as a tetrafunctional building block. The reactions are carried out using microwave‐assisted Yamamoto or Sonogashira cross‐coupling. Red insoluble powders are obtained, showing intense fluorescence. The polymer networks exhibit a high gas storage capability, with BET surface areas up to about 500 m2 · g−1.
Polysilsesquioxane nanosheets with a thickness of four nanometers and lateral dimensions of several hundreds of nanometers were synthesized by polymerization of a trifunctional monomer in the layer space of montmorillonite as the confined environment.
AFM image of a polymethylsilsesquioxane nanosheet. 相似文献
The kinetics of microemulsion polymerization depend on the structure of the initial microemulsion and the transport of species between the aqueous domain, the micelles, and the polymer particles. The water solubility of the monomer and the proximity of the initial microemulsion composition to a phase boundary are key considerations for studying microemulsion polymerization kinetics and producing the desired products. Complications frequently arise in the synthesis of copolymers or the incorporation of controlled polymerization mechanisms because of the compartmentalized nature of microemulsion polymerizations.
A new biomimetic approach for performing CaCO3 synthesis exclusively inside micron‐sized polyelectrolyte capsules, based on the fermentative formation of a precipitative agent (CO32− anion) by urease‐catalyzed urea hydrolysis, was developed. Precipitated CaCO3 completely fills the interior capsule volume and has a metastable vaterite phase.
Colloidal photonic crystals were prepared from monodisperse core–shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core–shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His‐tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric acid onto the core–shell colloids.
