Kang Hee Ku

Abstract Colloidal particles with controlled shape and internal structure have attracted great attention due to their novel morphologies and various potential applications. Among the diverse synthetic strategies toward anisotropically shaped polymer particles, facile and accurate engineering of such structures remains challenging. This review highlights the synthetic approaches to manipulate the shape of polymer particles driven by phase separation in emulsions upon solvent evaporation. And, spe

The tuning of interfacial properties at selective and desired locations on the particles is of great importance to create the novel structured particles by breaking the symmetry of their surface property. Herein, a dramatic transition of both the external shape and internal morphology of the particles of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) was induced by precise positioning of size-controlled Au nanoparticle surfactants (Au NPs). The size-dependent assembly of the Au NPs was localize

A series of porous block copolymer (BCP) particles with controllable morphology and pore sizes was fabricated by tuning the interfacial behavior of BCP droplets in oil-in-water emulsions. A synergistic adsorption of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) BCPs and sodium dodecyl sulfate (SDS) to the surface of the emulsion droplet induced a dramatic decrease in the interfacial tension and generated interfacial instability at the particle surface. In particular, the SDS concentration and

We report a simple and practical method for creating colloidal patchy particles with a variety of three-dimensional shapes via the evaporation-induced assembly of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) in an oil-in-water emulsion. Depending on the particle volume, a series of patchy particles in the shapes of snowmen, dumbbells, triangles, tetrahedra, and raspberry can be prepared, which are then precisely tuned by modulating the interfacial interaction at the part

Polymer particles that switch their shape and color in response to light are of great interest for the development of programmable smart materials. Herein, we report block copolymer (BCP) particles with reversible shapes and colors activated by irradiation with ultraviolet (UV) and visible lights. This shape transformation of the BCP particles is achieved by a spiropyran-dodecyltrimethylammoium bromide (SP-DTAB) surfactant that changes its amphiphilicity upon photoisomerization. Under UV light (

We report a simple and robust strategy to prepare pH-responsive biphasic Janus particles composed of polystyrene/poly(2-vinylpyridine) (PS/P2VP) homopolymers that are able to control the reversible formation, breakage, and switching of Pickering emulsions depending on their geometry- and pH-dependent hydrophilic–lipophilic balance. The chemical stability of these PS/P2VP Janus particles was tuned through the incorporation of cross-linkable benzophenone units along the backbone of the homopolymer

Self-assembly of block copolymers (BCPs) in evaporative emulsion provides a simple and effective route for the preparation of anisotropic particles with controlled shape and size. Understanding of thermodynamic phenomena associated with the bending/stretching of the BCP chains confined within the particles is necessary to enable precise control of the shape and microstructure of the particles. Herein, we report the systematic design of shape-anisotropic diblock copolymer (dBCP) particles based o

Multicolor emitting microspheres with three dimensionally controlled nanostructures are produced via a simple and efficient method. Location control and separation of the quantum dots (QDs) within the microspheres are achieved by a supramolecular assembly of block copolymer micelles to control the Förster resonance energy transfer efficiency between the different-colored QDs. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such mater

Interface engineering of evaporative emulsion droplets containing block copolymers (BCPs) provides an effective route to generate nonspherical particles. Here, we demonstrate the impact of length-controlled nanorods (NRs) on the interfacial properties of BCP emulsions to produce anisotropic BCP particles. A series of lamellae- and cylinder-forming polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and a series of NRs with different lengths (l) are coassembled, and selective arrangement of the NRs o

The effect of aspect ratio (AR) of nanorod surfactants on the shape and internal morphology of block copolymer (BCP) particles was systemically investigated using CuPt nanorods with different AR values ranging from 1 to 15. The positioning of the nanorods in the BCP particles was dependent strongly on their AR values, and it enabled the modulation of the interfacial properties at selective locations on the BCP particles, thus producing interesting morphological transition of the BCP particles.

Dynamically reconfigurable oil-in-water (o/w) Pickering emulsions are developed, wherein the assembly of particles (i.e., platinum-on-carbon and iron-on-carbon particles) can be actively controlled by adjusting interfacial tensions. A balanced adsorption of particles and surfactants at the o/w interface allows for the creation of inhomogeneity of the particle distribution on the emulsion surface. Complex Pickering emulsions with highly controllable and reconfigurable morphologies are produced in

Photoactive shape-changing particles offer a promising platform for smart materials with tunable properties at high spatiotemporal resolutions. Herein, a series of spiropyran-based surfactants with different alkyl spacer lengths are developed to achieve photoactive, shape-changing particles through confined self-assembly of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) within an evaporative emulsion. The length of the alkyl chain spacer between the spiropyran headgroup and ionic chain-end

ABSTRACT Combining the functionality of nanoparticles (NPs) with the processability of polymers offers great promise for designing novel materials. In particular, NPs with tailored surface properties can effectively modify the interface between two distinct fluids and/or different polymer matrices which allows them to function as efficient surfactants. The efficiency of NP surfactants is strongly affected by their size and shape, which influences their adsorption energy to the interface, and the

Co-assembly of block copolymers (BCPs) and organic/inorganic additives affords the design of various hierarchical nanostructures. In this work, we investigate the shape-changing capabilities of poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) BCP particles upon quaternization with a series of bromoalkyl benzene additives with different alkyl spacer lengths. The bromoalkyl benzene additives exhibit different hydrolyzing and quaternizing behaviors depending on their chemical structures. When benzyl

Diblock copolymer (dBCP) particles capable of dynamic shape and color changes have gained significant attention due to their versatility in programmable shapes and intricate nanostructures. However, their application in photonic systems remains limited due to challenges in achieving a sufficient number of defect-free photonic layers over a tens-of-micrometer scale. In this study, we present a pioneering demonstration of photonic dBCP particles featuring over 300 axially stacked photonic layers w