We report a stepwise assembly strategy for the integration of metal-organic cages (MOCs) into block copolymers (BCPs). This approach creates "block co-polyMOC" (BCPMOC) materials whose microscopic structures and mechanical properties are readily tunable by adjusting the size and geometry of the MOCs and the composition of the BCPs. In the first assembly step, BCPs functionalized with a pyridyl ligand on the chain end form star-shaped polymers triggered by metal-coordination-induced MOC assembly. The type of MOC junction employed precisely determines the number of arms for the star polymer. In the second step, microphase separation of the BCP is induced, physically cross-linking the star polymers and producing the desired BCPMOC networks in the bulk or gel state. We demonstrate that large spherical M12L24 MOCs, small paddlewheel M2L4 MOCs, or a mixture of both can be incorporated into BCPMOCs to provide materials with tailored branch functionality, phase separation, microdomain spacing, and mechanical properties. Given the synthetic and functional diversity of MOCs and BCPs, our method should enable access to BCPMOCs for a wide range of applications.

Assembling metal-organic framework (MOF)-based particles is an emerging approach for creating colloidal superstructures and hierarchical functional materials. However, realization of this goal requires strategies that not only regulate particle interactions but also harness the anisotropic morphologies and functions of various frameworks. Here, by exploiting depletion interaction induced by ionic amphiphiles, we show the assembly of a broad range of low-dimensional MOF colloidal superstructures, including 1D straight chains, alternating or bundled chains, 2D films of hexagonal, square, centered rectangular, and snowflake-like architectures, and quasi-3D supercrystals. With well-defined polyhedral shapes, the MOF particles are mutually oriented upon assembly, producing super-frameworks with hierarchically coordinated crystallinity and micropores. We demonstrate this advantage by creating functional MOF films with optical anisotropy, in our cases, birefringence and anisotropic fluorescence. Given the variety of MOFs available, our technique should allow access to advanced materials for sensing, optics, and photonics.

Phase segregation is ubiquitously observed in immiscible mixtures, such as oil and water, in which the mixing entropy is overcome by the segregation enthalpy1–3. In monodispersed colloidal systems, however, the colloidal–colloidal interactions are usually non-specific and short-ranged, which leads to negligible segregation enthalpy4. The recently developed photoactive colloidal particles show long-range phoretic interactions, which can be readily tuned with incident light, suggesting an ideal model for studying phase behaviour and structure evolution kinetics5,6. In this work, we design a simple spectral selective active colloidal system, in which TiO2 colloidal species were coded with spectral distinctive dyes to form a photochromic colloidal swarm. In this system, the particle–particle interactions can be programmed by combining incident light with various wavelengths and intensities to enable controllable colloidal gelation and segregation. Furthermore, by mixing the cyan, magenta and yellow colloids, a dynamic photochromic colloidal swarm is formulated. On illumination of coloured light, the colloidal swarm adapts the appearance of incident light due to layered phase segregation, presenting a facile approach towards coloured electronic paper and self-powered optical camouflage.

Classic binary materials, ranging from polymer blends to table salts, contain equilibrium phases or crystals of two interacting components. Here, we report on the construction of binary colloidal materials out of equilibrium by employing active particles and passive particles that dynamically interact and organize. Key to our scheme is the introduction of photoactive microspheres whose activity can be precisely tuned. This allows us to leverage the complex nonequilibrium interplay between the constituent components for dynamic coassembly. A wide variety of binary structures have thus been realized, including the liquid–crystal phases and crystal–crystal phases via phase separation and, counterintuitively, the binary crystalline compounds. The obtained structures are validated by computer simulations, which reveal unexpected kinetic pathways that are unique for active systems. With these findings, our strategy could facilitate the design and fabrication of multicomponent materials beyond equilibrium.