Light-responsive polymeric particles provide a versatile platform that can undergo precisely programmed shape and color transformations, offering opportunities for advanced multi-level memory systems. We report a block copolymer (BCP) particle system that functions as a structural memory element by reversibly switching among distinct morphologies and retaining each state with long-term stability. The incorporation of hydrazone-based photoswitches into polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) particles enables reversible and light-programmed transformations, governed by (E)/(Z) isomerization under dual-wavelength irradiation at 410 and 365 nm. The photoisomerization modulates the charge-transfer character of the N─Br interaction within P2VP domains, yielding three well-defined and distinct morphologies: lamellar ellipsoids (dark), networked lamellae (410 nm), and surface-wrapped discs (365 nm). These photoinduced morphologies can be reversibly switched over multiple cycles without detectable fatigue. Importantly, each programmed state persists as a metastable configuration over 30 days in the dark, retaining > 97% of its original morphology. Furthermore, the incorporation of domain-selective fluorescent dyes enables the system to provide real-time, color-coded visual readout of its encoded states via Förster resonance energy transfer modulation, opening new avenues for multi-level data storage with direct optical access.

Structurally colored colloids, or photonic pigments, offer a sustainable alternative to conventional dyes, yet existing systems are constrained by limited morphologies and complex synthesis. In particular, achieving angle-independent color typically relies on disordered inverse architectures formed from synthetically demanding bottlebrush block copolymers (BCPs), hindering scalability and functional diversity. Here, we report a conceptually distinct strategy to assemble three-dimensional inverse photonic glass microparticles using amphiphilic linear BCPs (poly(styrene-block-4-vinylpyridine), PS-b-P4VP) via an emulsion-templated process. By employing trans-1,2-dichloroethylene to promote interfacial water infiltration, nanoscale aqueous domains form within the organic phase and direct short-range-ordered pore structures. Evaporative solidification arrests these structures into porous photonic beads with angle-independent color. Systematic control of surfactant alkyl chain length and BCP molecular weight enables precise tuning of pore size, shell thickness, and visible-range optical output. Furthermore, post-chemical modification via quaternization of P4VP provides an orthogonal chemical handle to modulate interfacial instability and photonic behavior. This work expands the self-assembly capabilities of linear BCPs and establishes a modular, scalable platform for producing structurally and chemically programmable photonic pigments.

Light-responsive polymeric particles provide a versatile platform that can undergo precisely programmed shape and color transformations, offering opportunities for advanced multi-level memory systems. We report a block copolymer (BCP) particle system that functions as a structural memory element by reversibly switching among distinct morphologies and retaining each state with long-term stability. The incorporation of hydrazone-based photoswitches into polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) particles enables reversible and light-programmed transformations, governed by (E)/(Z) isomerization under dual-wavelength irradiation at 410 and 365 nm. The photoisomerization modulates the charge-transfer character of the N─Br interaction within P2VP domains, yielding three well-defined and distinct morphologies: lamellar ellipsoids (dark), networked lamellae (410 nm), and surface-wrapped discs (365 nm). These photoinduced morphologies can be reversibly switched over multiple cycles without detectable fatigue. Importantly, each programmed state persists as a metastable configuration over 30 days in the dark, retaining > 97% of its original morphology. Furthermore, the incorporation of domain-selective fluorescent dyes enables the system to provide real-time, color-coded visual readout of its encoded states via Förster resonance energy transfer modulation, opening new avenues for multi-level data storage with direct optical access.

Structurally colored colloids, or photonic pigments, offer a sustainable alternative to conventional dyes, yet existing systems are constrained by limited morphologies and complex synthesis. In particular, achieving angle-independent color typically relies on disordered inverse architectures formed from synthetically demanding bottlebrush block copolymers (BCPs), hindering scalability and functional diversity. Here, we report a conceptually distinct strategy to assemble three-dimensional inverse photonic glass microparticles using amphiphilic linear BCPs (poly(styrene-block-4-vinylpyridine), PS-b-P4VP) via an emulsion-templated process. By employing trans-1,2-dichloroethylene to promote interfacial water infiltration, nanoscale aqueous domains form within the organic phase and direct short-range-ordered pore structures. Evaporative solidification arrests these structures into porous photonic beads with angle-independent color. Systematic control of surfactant alkyl chain length and BCP molecular weight enables precise tuning of pore size, shell thickness, and visible-range optical output. Furthermore, post-chemical modification via quaternization of P4VP provides an orthogonal chemical handle to modulate interfacial instability and photonic behavior. This work expands the self-assembly capabilities of linear BCPs and establishes a modular, scalable platform for producing structurally and chemically programmable photonic pigments.

Freestanding networked nanoparticle (NP) films hold substantial potential due to their high surface areas and customizable porosities. However, NPs with high surface energies and heterogeneous sizes or shapes present considerable challenges as they tend to aggregate, compromising their structural integrities. In this study, we report the scalable fabrication of ultrathin, bicontinuous, and densely packed carbon NP films via Pickering emulsion-mediated interfacial assembly. This method enables the efficient transfer of closely packed NP networks from emulsions to air-water interface and ultimately to diverse substrates, which provides broad versatility for tailored applications. Utilizing the jamming structures of NPs at the fluid interface, we achieve precise control over film size with homogeneous thickness while minimizing material waste and facilitating recyclability. Notably, the films can be smoothly transferred to micropatterned, stretchable, and complex three-dimensional substrates, enabling the realization of robust conformal coatings. The resulting films exhibit high structural stability and flexibility, demonstrating significant potential for the design of stretchable and flexible devices.

Stimuli-responsive block copolymer (BCP) particles offer a promising platform for tunable photonic materials; however, most structural transformations originate from uniform lamellar templates that reorganize only under strong thermal or solvent-mediated activation. Here, we report a distinct pH-driven chain reorganization behavior in partially quaternized poly(styrene-<i>block</i>-2-vinylpyridine) (PS-<i>b</i>-P2VP) microparticles that initially possess heterogeneous internal morphologies, comprising PS-encapsulated P2VP domains and stacked lamellar domains. Upon acid exposure, protonation of unquaternized P2VP establishes a hydration-induced swelling gradient: less-constrained lamellae laterally expand and redistribute along interfaces, whereas PS-encapsulated lamellar regions act as rigid anchors. This anisotropic response progressively redistributes chain stress and solvation, transforming the stacked lamellae into an irregular, laterally dilated morphology with thin, hydrated P2VP layers. This progressive chain reorganization gives rise to a steady blue-shift in structural color from 622 to 478 nm, in line with the gradual contraction of domain periodicity. These findings reveal that structural heterogeneity can serve as an intrinsic driving force for topological reconstruction in vitrified BCP particles, enabling programmable, history-dependent photonic responses under mild aqueous conditions.

The spatial organization of amphiphiles within emulsions offers a versatile route to constructing complex soft-matter architectures. Here, we present the solvent-dependent interfacial behavior of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) copolymers in evaporative emulsions and its decisive role in dictating particle morphology. By systematically varying the solvent selectivity toward each block, we achieve precise control over the confined assembly of PS-b-P4VP, producing a continuous morphological evolution from nonporous spheres to porous particles, vesicles, and micellar structures. Enhanced affinity of solvents for the P4VP block promotes the polymer adsorption at the emulsion interface, triggering pronounced interfacial instabilities that drive hierarchical structure formation. Furthermore, variations in P4VP volume fraction and surfactant concentration modulate these interfacial dynamics, enabling a tunable library of well-defined polymer particles. This study establishes solvent selectivity as a powerful design parameter for manipulating interfacial self-assembly pathways of amphiphilic block copolymers, offering a robust and scalable strategy for engineering functional soft colloids.

Block copolymer (BCP) particles with tailored shapes and nanostructures hold promise for applications in cell adhesion, photonic system, and energy storage due to their unique optical and rheological properties. Conventional approaches relying on surfactant-mediated self-assembly often limit particle geometries to simple structures. Herein, we present a versatile approach to expand the morphology of poly(styrene-<i>block</i>-2-vinylpyridine) (PS-<i>b</i>-P2VP) BCP particles through the incorporation of 9-bromononanoic acid (BNA), a bifunctional additive that facilitates synergistic quaternization and protonation. Increasing the BNA-to-2VP molar ratio enhances P2VP hydrophilicity and decreases the pH value, driving dramatic shape transitions from onion-like spheres to tulip bulbs, ellipsoids, discs, and Janus cups. This morphological diversity is attributed to synergetic interfacial instability-driven water infiltration and pH-induced repulsion of protonated P2VP chains. Additives with a single functional group, however, yield limited morphologies, such as tulip bulbs or onion-like spheres. Notably, Janus cups fabricated <i>via</i> this strategy exhibit selective cargo-loading capabilities, highlighting the importance of precise control over the internal composition and structure of BCP particles.

Three-dimensionally ordered photonic colloids offer a unique opportunity to directly correlate internal nanoscale morphology with the macroscale optical response. Herein, we present pH-responsive poly(styrene-<i>block</i>-2-vinylpyridine) (PS-<i>b</i>-P2VP) colloids with stacked lamellar architecture that exhibit tunable structural color through controlled swelling dynamics. Cross-linking P2VP domains using 1,8-dibromooctane increases initial domain spacing, shifting color from violet to blue-green, while simultaneously restricting acid-induced swelling and red shift. In contrast, lower cross-linking permits significant anisotropic expansion upon protonation, enabling large color shifts from violet to red. These swelling behaviors arise from the formation of pyridinium cations and their interactions with counteranions, where anion hydration energy governs water uptake: highly hydrated species facilitate greater expansion, while less hydrophilic anions impose steric and electrostatic constraints. By systematically tuning cross-linking density, acid identity, and the molecular weight of PS-<i>b</i>-P2VP, we achieve continuous, full-spectrum modulation of structural color. This system enables real-time optical tracking of internal structural changes at the single-particle level, establishing a versatile platform for stimuli-responsive photonic materials with programmable color output.