Joona Bang 교수

The self-assembly of triblock copolymers of poly(ethylene oxide-b-methyl methacrylate-b-styrene) (PEO-b-PMMA-b-PS), where PS is the major component and PMMA and PEO are minor components, provides a robust route to highly ordered, nanoporous arrays with cylindrical pores of 10-15 nm that show promise in block copolymer lithography. These ABC triblock copolymers were synthesized by controlled living radical polymerization, and after solvent annealing, thin films showing defect-free cylindrical mic

An asymmetric poly(styrene-b-isoprene) diblock copolymer with block molecular weights of 13 000 and 71 000 g/mol, respectively, was dissolved at 1 vol % in a series of solvents with varying selectivity for styrene: dibuthyl phthalate (DBP), diethyl phthalate (DEP), and dimethyl phthalate (DMP). The degree of solvent selectivity was adjusted by mixing DBP/DEP and DEP/DMP in various proportions. With increasing solvent selectivity, the predominant micellar shape changes from spheres to cylinders t

A new crosslinking system based on azide-functionalized random copolymers has been defined for the preparation of substrates with controllable surface interactions. The azido group is used for both thermal- and photo-crosslinking, which is found to be very efficient. Furthermore, the use of UV irradiation for crosslinking enables the preparation of patterned surfaces by conventional photolithographic techniques, combining the “bottom-up” self-assembly of block copolymer strategies with tradition

Solvent cast diblock and triblock copolymer films of poly(ethylene oxide-b-styrene) (PEO-b-PS) and poly(ethylene oxide-b-methyl methacrylate-b-styrene) (PEO-b-PMMA-b-PS), with cylindrical microdomains of PEO or PMMA−PEO, have a high degree of lateral ordering after solvent annealing. The relative humidity of the vapor during the solvent annealing has been shown to play an important role in achieving this order. After solvent annealing under high humidity a PEO-b-PMMA-b-PS triblock copolymer havi

Micropatterns with a high stability, definition, and resolution are an absolute requirement in advanced display technology. Herein, patternable perovskite nanocrystals (PNCs) with excellent stability were prepared by exchanging pristine ligands with multifunctional polymer ligands, poly(2-cinnamoyloxyethyl methacrylate). The polymer backbone contains a cinnamoyl group that has been widely employed as a photo-cross-linker under 365 nm UV irradiation. Also, the terminal group is readily adjustable

We introduce a novel and facile approach to improve the desalination performance of pressure-driven layer-by-layer (LbL) assembled membranes. Electrostatic LbL multilayers composed of weak polyelectrolytes (PEs), e.g., cationic poly(allylamine hydrochloride) (PAH) and anionic poly(acrylic acid) (PAA), were prepared on commercial polysulfone substrates. In order to measure the ion rejection and permeate flux of these membranes, the ionic concentration of the feed solution and operating pressure w

Quantum dot (QD)-based displays call for nondestructive, high-throughput, and high-resolution patterning techniques with micrometer precision. In particular, self-emissive QD-based displays demand fine patterns of conductive QD films with uniform thickness at the nanometer scale. To meet these requirements, we functionalized QDs with photopatternable and semiconducting poly(vinyltriphenylamine-<i>random</i>-azidostyrene) (PTPA-N₃-SH) ligands in which hole-transporting triphenylamine a

The temperature dependence of the micelle structures formed by poly(styrene-b-isoprene) (SI) diblock copolymers in the selective solvents diethyl phthalate (DEP) and tetradecane (C14), which are selective for the PS and PI blocks, respectively, have been investigated by small angle neutron scattering (SANS). Two nearly symmetric SI diblock copolymers, one with a perdeuterated PS block and the other with a perdeuterated PI block, were examined in both DEP and C14. The SANS scattering length densi

Uncharged block copolymer micelles display thermoreversible transitions between close-packed and bcc lattices for a range of concentration, solvent selectivity, and copolymer composition. Using small-angle x-ray scattering on shear-oriented solutions, highly aligned fcc crystals are seen to transform epitaxially to bcc crystals, with fcc/bcc orientational relationships that are well established in martensitic transformations in metals. The transition is driven by decreasing solvent selectivity w

This review article focuses on recent advances of bottlebrush copolymers prepared by a ring-opening metathesis polymerization, from synthesis efforts to properties and applications.

The epitaxial relationships between two close-packed lattices (face-centered cubic (fcc) and hexagonally close packed (hcp)) and the body-centered cubic (bcc) lattice of spherical micelles were investigated by small-angle X-ray scattering (SAXS) in two in situ shear cells. Two symmetric poly(styrene-b-isoprene) diblock copolymers with block molecular weights of 8.0 × 103 and 7.0 × 103 g/mol, and 1.5 × 104 and 1.5 × 104 g/mol, respectively, were employed. Thermoreversible fcc → bcc order−order tr

Abstract Thermally stable core–shell gold nanoparticles (Au NPs) with highly grafted polymer shells were synthesized by combining reversible addition‐fragmentation transfer (RAFT) polymerization and click chemistry of copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). First, alkyne‐terminated poly(4‐benzylchloride‐ b ‐styrene) (alkyne‐PSCl‐ b ‐PS) was prepared from the alkyne‐terminated RAFT agent. Then, an alkyne‐PSCl‐ b ‐PS chain was coupled to azide‐functionalized Au NPs via the CuAAC react