نتایج جستجو برای: block copolymers
تعداد نتایج: 164252 فیلتر نتایج به سال:
Block copolymers remain one of the most extensively studied and utilized classes of macromolecules due to their extraordinary abilities to (i) self-assemble spontaneously into a wide variety of soft nanostructures and (ii) reduce the interfacial tension between, and thus compatibilize, immiscible polymer pairs. In bilayered thin-film laminates of immiscible homopolymers, block copolymers are si...
Two-dimensional, hierarchical assemblies of nanorods were obtained by exploiting the structures afforded by block copolymers in ultrathin films. Under the appropriate conditions, the nanorods segregate to the film surface already upon casting the composite film, and organize with the block copolymer through phase separation. In this paper we compare the structures formed by CdSe nanorods of thr...
The self-assembly processes of miktoarm star-like block copolymers (Ax1)y-C-(Bx2)y, in which y homopolymer chains of type A with chain length x1 as well as y chains of type B with chain length x2 are connected to a center core C, are investigated by using Brownian dynamics simulations. We focus on the selective solvent condition, i.e., the solvent is poor for components B and C, but varies from...
We consider orientation mechanisms for block copolymers in an electric field. Theoretical and experimental studies have shown that nonuniformity of the dielectric constant gives rise to a preferred orientation of the melt with respect to the applied field. We show that the presence of ions, as found in anionically prepared copolymers, may increase the alignment effect markedly. Time-varying (ac...
While the performance of polymer−polymer bulk heterojunction organic photovoltaics (OPVs) is poor compared with polymer−fullerene OPVs, reducing or eliminating micrometer-scale phase separation in all-polymer OPVs may dramatically improve performance. Herein, we demonstrate that 2-ureido-4[1H]-pyrimidinone (UPy) quadruple hydrogen bonding interactions can be used to prevent micrometer-scale pha...
Three polystyrene-block-poly(2-vinylpyridine) (S2VP diblock) and three polystyrene-block-poly(4-vinylpyridine) (S4VP diblock) copolymers with varying molecular weights and block compositions were synthesized via anionic polymerization, and their order-disorder transition temperatures (TODTs) were determined using oscillatory shear rheometry and small-angle X-ray scattering (SAXS). It has been f...
A dissipative particle dynamics (DPD) simulation is performed to investigate the spontaneous onion shape vesicle formation and fusion of A6(B2)3 type comb-like block copolymers with a semiflexible hydrophobic backbone. Our results show that comb-like block copolymers of A6(B2)3 type may be a good candidate for onion shape vesicle formation. The spontaneous fusion dynamics between the onion shap...
The self-asembly of block copolymers is a promising platform for the "bottom-up" fabrication of nanostructured materials and devices. This review covers some of the advances made in this field from the laboratory setting to applications where block copolymers are in use.
A new means of controlling the order-disorder transition of block copolymers is presented. By applying small electrical potentials (2 V/cm) to disordered solutions of an organometallic block copolymer, oriented ordered grains were obtained near the positive electrode. After reversing the electrical bias on the system, the ordered grains disappeared, and new, oriented, ordered regions were forme...
This article deals with recent progress including the author’s work in the field of block copolymer self-assembly in solution and on solid surfaces. The synthesis methods for producing block copolymers with well-defined structures, molecular weights and composition are outlined with emphasis on ionic and controlled free radical polymerization techniques. A general overview of the preparation, c...
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