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In this study, we demonstrate the surfactant-assisted synthesis of uniform-sized titania microspheres and their clusters for highly responsive optical materials. Monodisperse titanium glycolate microspheres were produced by controlled hydrolysis of glycolated titanium butoxide in acetone using surfactant as a stabilizer. The diameter of as-prepared particles ranged from 230 to 650 nm and was finely controlled by changing the concentrations of titanium butoxide and surfactant. In particular, the tunable range of the particle size was at a few tens of nanometers scale by the surfactant concentration, which was much finer than that by the concentration of titanium butoxide. Then, as-prepared titanium glycolate microspheres were transformed into monodisperse titania microspheres of anatase phase by heat treatment. Pure clusters of titania microspheres with an identical configuration were obtained by encapsulating a certain number of microspheres in emulsion droplets and subsequently evaporating the emulsion phase to induce self-assembly. Dynamic and static light scattering experiments show that the pure clusters with an identical configuration were well dispersed, and the refractive index of anatase phase titania microspheres was about 2.2. In addition, monodisperse Eu-doped titanium glycolate microspheres were prepared for phosphorescence sources by adding both a soluble precursor Eu(NO 3) 3·5H 2O and glycolated titanium butoxide in acetone. Finally, photoluminescence properties of Eu-doped titania microspheres were examined after annealing. [ABSTRACT FROM AUTHOR]

We prepared polymeric microparticles with coordinated patches using oil-in-water emulsion droplets which were stabilized by adsorbed colloidal polystyrene (PS) latex particles. The oil phase was photocurable ethoxylated trimethylolpropane triacrylate (ETPTA), and the particle-armored oil droplets were solidified by UV irradiation within a few seconds to produce ETPTA−PS composite microparticles without disturbing the structures. Large armored emulsion drops became raspberry-like particles, while small emulsion drops with a few anchored particles were transformed into colloidal clusters with well-coordinated patches. For high-molecular-weight PS particles with low chemical affinity to the ETPTA monomer, the morphology of the patchy particle was determined by the volume of the emulsion drop and the contact angle of the emulsion interface on the PS particle surface. Meanwhile, for low-molecular-weight PS particles with high affinity, the ETPTA monomers were likely to swell the adsorbed PS particles, and distinctive morphologies were induced during the shrinkage of emulsion drops and the phase separation of ETPTA from the swollen PS particles. In addition, colloidal particles with large open windows were produced by dissolving the PS particles from the patchy particles. We observed photoluminescent emission from the patchy particles in which dye molecules were dispersed in the ETPTA phase. Finally, we used Surface Evolver simulation to predict equilibrium structures of patchy particles and estimate surface energies which are essential to understand the underlying physics. [ABSTRACT FROM AUTHOR]

In this Article, we report on a packing scheme of monodisperse colloidal nanospheres by aerosol-assisted clustering. When an aqueous suspension of colloidal nanospheres was sprayed into aerosol droplets by an ultrasonic nebulizer, the nanospheres were encapsulated in the aerosol droplets and the evaporation of water from the droplets at high temperatures led to the packings of nanospheres. The configurations of the colloidal nanospheres minimized the interparticle potential energy or the second moment of mass distribution depending on the number of the constituting nanospheres. Other types of nonspherical microparticles or hollow microclusters were also produced by self-organizing organic−inorganic binary colloids of different sizes in an aerosol spray pyrolysis reactor. The aerosol-assisted fabrication of colloidal clusters was very effective as compared to the method based on oil-in-water or water-in-oil emulsions, in which the removal of residual oil was not easy and time-consuming. [ABSTRACT FROM AUTHOR]

Colloidal spheres with unique internal morphologies were prepared by blending symmetrical poly(styrene)-block-poly(butadiene) (PS-b-PB) and polystyrene homopolymer (hPS) in emulsion droplets and carrying out subsequent solvent evaporation. We found various unprecedented microphases in these spherically confining geometries that depend on the ratio (r) of the molecular weight of hPS relative to that of the PS block of PS-b-PB and the ratio of the diameter (D) of the emulsion drop to the feature spacing (L0) of the phase-separated periodic domains. In particular, the effect of spherical confining geometry was pronounced for D/L0< 15, in which directionally oriented structures such as helices and hoops were observed. For r <1, the PB domains exhibit transitions between morphological microphases of lamellae, perforated lamellae, cylinders, and spheres, in that order, as the weight fraction of hPS () is increased. The lamellae or perforated lamellae are ordered in concentric shells. Interestingly, cylindrical domains of PB blocks consisting of circular helices or stacked hoops were observed for 0.38 ≤ ≤ 0.54, in which the particle shape is slightly deformed from spherical to accommodate the ordered regular packing of the hoops and helices. For r∼ 2, concentric spherical lamellae are produced for up to 0.30, above which macrophase separation occurs and the spherical lamellae are either nonconcentric or deformed into a domelike structure. For r∼ 4, an onion-like structure is present for the entire range of , with a lamellar spacing that is nearly independent of due to macrophase separation. In particular, for r∼ 1, spherical lamellar morphology is present up to 0.30, and complex anomalous structures such as multiply jointed hoops are present for ≥ 0.32 because of the combined effects of micro- and macrophase separations. [ABSTRACT FROM AUTHOR]

Superhydrophobic nanofiber films were created from electrospun nanofibers with undulated surfaces at multiple scales in micrometers and nanometers. The electrospun nanofibers were produced out of aqueous solutions which contained water-soluble polymers and different colloids:  monodisperse silica or polystyrene microspheres for larger particles and monodisperse silica nanoparticles for smaller particles. Various types of fibrous films were produced depending on the properties of the dispersing medium, the effects of additives, and the compositions of the bidisperse colloids. When polystyrene microspheres were used as sacrificial templates, macropores were left behind in the nanofibers during the removal of polystyrene microspheres by calcination. The nonwoven films of electrospun nanofibers, which were decorated with silica microspheres or macropores, could be continuously produced with considerable ease under a relatively wide range of operating conditions. The surface properties of the films were characterized by contact angle measurement and an X-ray photoelectron spectrometer. Through the surface modification of the electrospun nanofibers with fluorinated silane coupling agents, superhydrophobic surfaces with low sliding angles were successfully prepared. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrated a unique and simple method for fabricating colloidal particles of complex structures using oil-in-water emulsion droplets as confined geometries. A variety of structural motifs were produced using binary colloids of microspheres of polystyrene (PS) or silica and nanosized particles as the second component. When PS or silica microspheres and PS macromolecules were dispersed in oil-in-water emulsion droplets, particles with well-coordinated patches were obtained because the PS macromolecules partially covered the microsphere clusters. When silica or gold nanoparticles were dispersed together with the PS microspheres in oil-in-water emulsion droplets instead of PS macromolecules, composite particles with patches were obtained. In this case, silica or gold shell structures with well-coordinated windows were produced by selectively removing the large PS microspheres from the organic−inorganic composite clusters. [ABSTRACT FROM AUTHOR]

Most of the colloidal clusters have been produced from oil-in-water emulsions with identical microspheres dispersed in oil droplets. Here, we present new types of binary colloidal clusters from phase-inverted water-in-oil emulsions using various combinations of two different colloids with several size ratios: monodisperse silica or polystyrene microspheres for larger particles and silica or titania nanoparticles for smaller particles. Obviously, a better understanding of how finite groups of different colloids self -organize in a confined geometry may help us control the structure of matter at multiple length scales. In addition, since aqueous dispersions have much better phase stability, we could produce much more diverse colloidal materials from water-in-oil emulsions rather than from oil-in-water emulsions. Interestingly, the configurations of the large microspheres were not changed by the presence of the small particles. However, the arrangement of the smaller particles was strongly dependent on the nature of the interparticle interactions. The experimentally observed structural evolutions were consistent with the numerical simulations calculated using Surface Evolver. These clusters with nonisotropic structures can be used as building blocks for novel colloidal structures with unusual properties or by themselves as light scatterers, diffusers, and complex adaptive matter exhibiting emergent behavior. [ABSTRACT FROM AUTHOR]

Patchy particles with shape complementarity can serve as building blocks for assembling colloidal superstructures. Alternatively, encoding information on patches using DNA can direct assembly into a variety of crystalline or other preprogrammed structures. Here, we present a tool where DNA is used both to engineer shape and to encode information on colloidal particles. Two reactive oil emulsions with different but complementary DNA (cDNA) brushes are assembled into CsCl-like crystalline lattices. The DNA brushes are recruited to and ultimately localized at the junctions between neighboring droplets, which gives rise to DNA-encoded faceted patches. The emulsions are then solidified by ultraviolet (UV) polymerization, producing faceted patchy particles. The facet size and DNA distribution are determined by the balance between the DNA binding energy and the elastic deformation energy of droplets. This method leads to a variety of new patchy particles with directional interactions in scalable quantities. [ABSTRACT FROM AUTHOR]

Reports on a fabrication method for making an array of uniform micron-sized ceramic spheres with ordered macropores having pore diameters comparable to optical wavelengths. Key feature of the polymer template; Scanning electron micrographs of polymeric microstructures that were fabricated by templating silica colloidal crystals.

Polystyrene-coated gold nanoparticles (molecular weight (Mn) of PS ∼1300 g/mol, average particle diameter d(core shell) ∼ 9.2 ± 2.2 nm, corresponding to a high areal chain density of PS) are incorporated into symmetric poly(styrene-b-2 vinylpyridine) diblock copolymers with total Mn∼ 60 000−380 000 g/mol at volume fractions of 0.07−0.32. For all Mnof diblock copolymers and particle filling fractions examined, particles are centralized in the PS domains with Gaussian distribution profiles. The distribution width generally decreases as the PS domain size decreases or as the particle weight fraction increases. These observations are discussed in terms of the relative entropic contributions of the polymer chains and particles. [ABSTRACT FROM AUTHOR]

Monodisperse aqueous emulsion droplets encapsulating colloidal particles were produced in the oil phase, and controlled microwave irradiation of the aqueous drop phase created spherical colloidal crystals by so-called evaporation-induced self-organization of the colloidal particles. Unlike usual colloidal crystals, colloidal crystals in spherical symmetry (or photonic balls) possessed photonic band gaps for the normal incident light independent of the position all over the spherical surface. While the consolidation of colloidal particles in emulsion droplets in an oven took several hours, the present microwave-assisted evaporation could reduce the time for complete evaporation to a few tens of minutes. Under the microwave irradiation, the aqueous phase in emulsions was superheated selectively and the evaporation rate of water could be controlled easily by adjusting the microwave intensity. The result showed that the packing quality of colloidal crystals obtained by the microwave-assisted self-organization was good enough to show photonic band gap characteristics. The reflectance of our photonic balls responded precisely to any change in physical properties including the size of colloidal particles, refractive index mismatch, and angle of the incident beam. In particular, for polymeric particles, the photonic band gap could be tuned by the intensity of microwave irradiation, and the reflection color was red-shifted with stronger microwave irradiation. Finally, for better photonic band gap properties, inverted photonic balls were prepared by using the spherical colloidal crystals as sacrificial templates. [ABSTRACT FROM AUTHOR]

Harmonic combination of microprism-based holographic lithography (μHL) and surfactant templating was used to create arrayed and free-standing hierarchical structures in a facile manner. The multiscale ordered structure obtained had a triple hierarchy: micrometer scale 2D array of submicrometer scale 3D macropores produced from μHL, and mesopores from surfactant self-assembly. [ABSTRACT FROM AUTHOR]

We report our direct Brownian motion observation of Fe2O3 magnetic cube chains under external magnetic fields, where the possibility of tuning the Brownian motion characteristics, such as diffusivity, by magnetic fields is realized. It has been experimentally demonstrated that the diffusivity is modified with an angular dependency on the magnetic field direction, well explained based on the Stokes-Einstein relation considering an effective cross-sectional change of magnetic cube chains. [ABSTRACT FROM AUTHOR]

Although sonodynamic therapy (SDT) has emerged as a potential alternative to conventional photodynamic therapy, the low quantum yield of the sonosensitizer such as TiO2 nanoparticles (NPs) is still a major concern. Here, we have developed hydrophilized Au-TiO2 nanocomposites (HAu-TiO2 NCs) as sonosensitizers for improved SDT. The physicochemical properties of HAu-TiO2 NCs were thoroughly studied and compared with their counterparts without gold deposition. Upon exposure of HAu-TiO2 NCs to ultrasound, a large quantity of reactive oxygen species (ROS) were generated, leading to complete suppression of tumor growth after their systemic administration in vivo. Overall, it was evident that the composites of gold with TiO2 NPs significantly augmented the levels of ROS generation, implying their potential as SDT agents for cancer therapy. [ABSTRACT FROM AUTHOR]

The smallness of natural molecules and atoms with respect to the wavelength of light imposes severe limits on the nature of their optical response. For example, the well-known argument of Landau and Lifshitz and its recent extensions that include chiral molecules show that the electric dipole response dominates over the magneto-electric (bianisotropic) and an even smaller magnetic dipole optical response for all natural materials. Here, we experimentally demonstrate that both these responses can be greatly enhanced in plasmonic nanoclusters. Using atomic force microscopy nanomanipulation technique, we assemble a plasmonic metamolecule that is designed for strong and simultaneous optical magnetic and magneto-electric excitation. Angle-dependent scattering spectroscopy is used to disentangle the two responses and to demonstrate that their constructive/destructive interplay causes strong directional scattering asymmetry. This asymmetry is used to extract both magneto-electric and magnetic dipole responses and to demonstrate their enhancement in comparison to ordinary atomistic materials. [ABSTRACT FROM AUTHOR]

We demonstrate a method to create high-density DNA coatings on colloidal particles that can be used for DNA-mediated self-assembly of single- and multiple-component colloidal crystals. First, we modify an amphiphilic diblock copolymer consisting of a hydrophobic polystyrene (PS) block and a hydrophilic poly(ethylene oxide) (PEO) block with azide functional groups at the end (poly(ethylene oxide)-N3). Then, we introduce the diblock copolymers into an aqueous suspension of colloidal polymer particles swollen with a solvent. The hydrophobic PS anchoring block is incorporated into the swollen polymer spheres and physically trapped when the solvent is removed, resulting in a dense PEO polymer brush with azide functional end groups. Finally, single-stranded DNA strands with sticky ends are attached to the azide groups using strain-promoted azide-alkyne cycloaddition (SPAAC, a copper-free click chemistry). This procedure results in a high areal coverage of up to 225?000 DNA strands on 1-µm-diameter particles. The ssDNA-coated particles with sticky ends can readily form either face-centered-cubic (fcc) or cesium chloride (CsCl) crystal structures when annealed just below the melting temperature of the DNA-coated particles. [ABSTRACT FROM AUTHOR]

Surface carbon coating to improve the inherent poor electricalconductivity of lithium iron phosphate (LiFePO4, LFP) hasbeen considered as most efficient strategy. Here, we also report oneof the conventional methods for LFP but exhibiting a specific capacitybeyond the theoretical value, ultrahigh rate performance, and excellentlong-term cyclability: the specific capacity is 171.9 mAh/g (70 μm-thickelectrode with ∼10 mg/cm2loading mass) at 0.1 C(17 mA/g) and retains 143.7 mAh/g at 10 C (1.7 A/g) and 95.8% of initialcapacity at 10 C after 1000 cycles. It was found that the interiorconformal N–C coating enhances the intrinsic conductivity ofLFP nanorods (LFP NR) and the exterior reduced graphene oxide coatingacts as an electrically conducting secondary network to electricallyconnect the entire electrode. The great electron transport mutuallypromoted with shorten Li diffusion length on (010) facet exposed LFPNR represents the highest specific capacity value recorded to dateat 10 C and ultralong-term cyclability. This conformal carbon coatingapproach can be a promising strategy for the commercialization ofLFP cathode in lithium ion batteries. [ABSTRACT FROM AUTHOR]

We report on synthetic strategies tofabricate DNAcoated micrometer-sized colloids that, upon thermal annealing, selfassemble into various crystal structures. Colloids of a wide range of chemical compositions, including poly(styrene), poly(methyl methacrylate), titania, silica, and a silica-methacrylate hybrid material, are fabricated with smooth particle surfaces and a dense layer of surface functional anchors. Single-stranded oligonucleotides with a short sticky end are covalently grafted onto particle surfaces employing a strain-promoted alkyne-azide cycloaddition reaction resulting in DNA coatings with areal densities an order of magnitude higher than previously reported. Our approach allows the DNA-coated colloids not only to aggregate upon cooling but also to anneal and rearrange while still bound together, leading to the formation of colloidal crystal compounds when particles of different sizes or different materials are combined. [ABSTRACT FROM AUTHOR]

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 localized preferentially at the interface between the P4VP domain at the particle surface and the surrounding water, which generated a balanced interfacial interaction between two different PS/P4VP domains of the BCP particles and water, producing unique convex lens-shaped BCP particles. In addition, the neutralized interfacial interaction, in combination with the directionality of the solvent-induced ordering of the BCP domains from the interface of the particle/water, generated defect-free, vertically ordered porous channels within the particles. The mechanism for the formation of these novel nanostructures was investigated systemically by varying the size and the volume fraction of the Au NPs. Furthermore, these convex lens-shaped particles with highly ordered channels can be used as a microlens, in which the light can be concentrated toward the focal point with enhanced near-field signals. And, these particles can possess additional optical properties such as unique distribution of light scattering as a result of the well-ordered Au cylinders that filled into the channels, which hold great promise for use in optical, biological-sensing, and imaging applications. [ABSTRACT FROM AUTHOR]

The preparation of anisotropic colloidal particles by a simple yet versatile temperature-controlled swelling process is described. The resulting polymeric particles feature a surface dimple, the size and shape of which were determined by the amount of oil captured in particles and the interfacial tension between the three phases: polystyrene (PS), decane, and the suspending medium. Following the removal of free or physically adsorbed surfactant from the swollen particles, hydrophobic dimples were produced upon evaporation of the oil phase. We demonstrate the spontaneous assembly of these 'dimpled particles' into dumbbell shapes or trimers through a site-selective hydrophobic interaction. [ABSTRACT FROM AUTHOR]

Colloidal microcapsules of thin nanoshell membranes were prepared by the evaporation-induced self-assembly of poly(styrene)-block-poly(butadiene)-block-poly(styrene) (SBS) triblock copolymers inside the oil phase of a water-in-oil-in-water (W/O/W) double emulsion, which was prepared via a two-step sequential emulsification process. To see the nanoconfinement effect, the shell thickness was kept very thin and comparable to the feature scale of self-organized nanostructure. By exploiting the density mismatch between the microcapsules and the continuous medium, single-cored microcapsules with thin shells were selectively separated from mixtures of multicored microcapsules or thick-shelled microcapsules. The internal morphology of the membrane could be modulated by controlling the volume fractions of styrene and butadiene blocks, which was achieved simply by adding polystyrene homopolymer of relatively low molecular weight. By varying the amount of homopolymer, various morphologies were produced in the microcapsule membranes, including lamellae, perforated lamellae, and cylindrical and spherical phases. Moreover, the addition of polystyrene homopolymer could be used to control the mechanical characteristics of the microcapsules. [ABSTRACT FROM AUTHOR]

The dynamic breakup of emulsion droplets was demonstrated in double-layered microfluidic devices equipped with designed pneumatic actuators. Uniform emulsion droplets, produced by shearing at a T-junction, were broken into smaller droplets when they passed downstream through constrictions formed by a pneumatically actuated valve in the upper control layer. The valve-assisted droplet breakup was significantly affected by the shape and layout of the control valves on the emulsion flow channel. Interestingly, by actuating the pneumatic valve immediately above the T-junction, the sizes of the emulsion droplets were controlled precisely in a programmatic manner that produced arrays of uniform emulsion droplets in various sizes and dynamic patterns. [ABSTRACT FROM AUTHOR]

A self-assembled monolayer (SAM) of octanethiol was vapor-deposited onto the surface of copper (Cu) nanoparticles as a means of preventing oxidation. The presence of octanethiol on the surface of Cu nanoparticles was verified using Fourier transform infrared spectroscopy and transmission electron microscopy. The electrical resistance of copper nanoparticles with deposition of a 12-nm thickness of octanethiol on the surface was found to be 100 times greater than that of uncoated powders, indicating uniform SAM coating of the particles. [ABSTRACT FROM AUTHOR]

This paper reports a continuous roll-to-roll printing of mesh patterns of silver oxide pastes on flexible polymer films and subsequent thermal treatment at 150 °C of the patterned pastes to convert to silver patterns. The pastes consist of silver(I) oxide particles, silver salt of tertiary fatty acid, AgOCO−C(CH3)2−(CH2)n−CH3and α-terpineol as the solvent. During the thermal process, nanosized silver particles were formed by the thermal reduction of silver oxide particles and the salt, followed by spontaneous condensation and further fusing, resulting in conductive silver films. The linear chain length nof silver salt, AgOCO−C(CH3)2−(CH2)n−CH3, in the pastes, affects the electrical conductivity of resulting silver films significantly. An optimal range of linear chain length is found as n= 5−9. In the case of the paste with n= 5, an optimal weight fraction range of the salt in the paste is found as 20−40 wt % if the solvent composition is held constant at 20 wt %. Using the paste with an optimal composition, we obtained high-performance electromagnetic wave interference (EMI) shielding films that have shown a comparable shielding effectiveness as that made of conventional sputtered metallic silver films. [ABSTRACT FROM AUTHOR]

We prepared polymeric structures with unusual complexity in surface morphology derived from photocurable emulsion droplets dispersed in an aqueous medium. The emulsion droplets a few tens of micrometers in size were stabilized with relatively small hydrophobic particles that were bound to the emulsion interfaces. The particle binding tended to immobilize the oil-in-water emulsion interface and dramatically increased the structural relaxation time of the interface deformation over a few days relative to a few milliseconds for an otherwise clean interface. In particular, perfectly immobilized emulsion drops maintained nonspherical elongated structures that were formed by shear-induced emulsification and could not be relaxed to a spherical shape. This property is useful for broad research areas ranging from crystallography and buckling phenomena to materials fabrication. The configuration of small particles on the interface and the “raspberry” shape of particle-stabilized emulsions were captured successfully by photocuring the emulsion droplets because the small bound particles immobilized the emulsion droplets. By selectively removing the small particles from the particle-covered polymeric structures, we prepared dimpled microparticles with various shapes. The dimple geometry depended on the interfacial properties or phase affinity of the small particles. The contact angle and binding energy of the particles were calculated on the basis of the dimple geometry. In addition, buckling phenomena of the particle-stabilized emulsions were observed when volatile oil was added to the photocurable resin. [ABSTRACT FROM AUTHOR]

Onionlike block copolymer particles containing a well-ordered gold nanoparticle array were prepared with the help of amphiphilic block copolymer used as a surfactant. The location of gold nanoparticles ordered in the specific position of block copolymer domain was systematically investigated by tuning the invariant polymerization index of the block copolymer and the areal chain density (Σ) of gold nanoparticles. [ABSTRACT FROM AUTHOR]

A biocompatible polymer–gold nanorod (P-AuNR) conjugate was developed as a thermo-chemotherapeutic nano-sized drug carrier for cancer therapy using near-infrared (NIR) light as an external trigger. The amphiphilic polymer, poly(ethylene glycol)-block-poly(caprolactone) (PEG-b-PCL) bearing a disulfide bond, was prepared using a facile synthetic route via copper(I)-free click chemistry and covalently linked to AuNR. The chemical structures and successful conjugation of PEG-b-PCL were analyzed using 1H NMR and FT-IR. Doxorubicin (DOX), a hydrophobic anticancer drug, was effectively loaded into the hydrophobic PCL domain of P-AuNR through a simple dialysis method. P-AuNR showed longitudinal plasmon resonance absorption at the NIR region, thus generating heat under irradiation at 808 nm. Interestingly, exposure of P-AuNRs to NIR induced a structural change in the PCL block from a crystalline to an amorphous state, leading to the temporally controlled release of DOX. No significant release of DOX was observed from P-AuNRs under physiological conditions (pH 7.4), whereas the release rate of DOX was remarkably enhanced in response to NIR irradiation. In vitro cellular experiments to assess cytotoxicity and intracellular drug release behavior of DOX-P-AuNRs demonstrated that the release of DOX could be selectively regulated by NIR irradiation. Overall, DOX-P-AuNRs might have the potential to overcome the indiscriminate toxicity of free DOX. [ABSTRACT FROM AUTHOR]

We present a novel method for producing structured nanoporous thin films using block copolymer (BCP) micelles loaded with metallic ions. The BCP micellar thin films containing gold (Au) ions were prepared by spin-coating poly(styrene-block-4-vinylpyridine) (PS-b-P4VP) micelle solutions in which Au precursors (AuCl4−) were selectively loaded onto the P4VP core. When the micellar films were exposed to cetyltrimethylammonium bromide (CTAB) solutions, the Au precursors were selectively extracted from the P4VP domains due to their strong electrostatic interaction with CTAB, leading to the formation of pores in the micelles. Consequently, regularly patterned nanoporous surfaces were formed. By controlling the molecular weight (Mn) of PS-b-P4VP and the amount of Au precursors (λ) that were loaded in the P4VP domains, the pore size and depth could be tuned precisely. In particular, when a sufficient amount of Au precursors was loaded (λ ≥ 0.3), the porous surface nanostructure was well developed. In addition, the pore size and depth of the nanostructure increased as the λ value increased. For instance, when the λ value increased from 0.3 to 1.0, the pore size increased from 22.8 nm to 28.8 nm, and the pore depth increased from 2.1 nm to 3.2 nm. Interestingly, the transition from the nonporous structures to the porous structures in the micellar film could be reversibly controlled by adding and removing the Au precursors in the film. Moreover, our method for the preparation of nanoporous films can be extended to micellar film by incorporating other metal ions such as silver (Ag) and iron (Fe). [ABSTRACT FROM AUTHOR]