A simple, yet robust route to prepare polymer nanoparticles with tunable internal structures through supramolecular assembly within emulsion droplets is presented. Nanoparticles with various internal morphologies, including dispersed spheres, dispersed spirals, stacked toroids, and concentric lamellae, are obtained due to the 3D confinement and variation of hydrogen-bonding agent. This method also allows us to form mesoporous particles through further disassembly of the supramoleclar assemblies by rupturing the hydrogen bonding.

Worm holes: Cylindrical or wormlike block copolymer micelles with gold nanoparticles encapsulated in a micellar core were fabricated through directed supramolecular assembly. This versatile approach allows fine‐tuning of interparticle spacing and micellar morphology by varying the content of the nanoparticles or hydrogen bonding agent in the supramolecular assemblies.

A general and versatile route to prepare hierarchical polymer microparticles via interfacial instabilities of emulsion droplets is demonstrated. Uniform emulsion droplets containing hydrophobic polymers and n‐hexadecanol (HD) are generated through microfluidic devices. When organic solvent diffuses through the aqueous phase and evaporates, shrinking emulsion droplets containing HD and polystyrene (PS) will trigger interfacial instabilities to form microparticles with wrinkled surfaces. Interestingly, surface‐textures of the particles can be accurately tailored from smooth to high textures by varying the HD concentration and/or the rate of solvent evaporation. Moreover, composite particles can be generated by suspending different hydrophobic species to the initial polymer solutions. This versatile approach for preparing particles with highly textured surfaces can be extended to other type of hydrophobic polymers which will find potential applications in the fields of drug delivery, tissue engineering, catalysis, coating, and device fabrication.

Nano-objects are generated through 3D confined supramolecular assembly, followed by a sequential disintegration by rupturing the hydrogen bonding. The shape of the nano-objects is tunable, ranging from nano-disc, nano-cup, to nano-toroid. The nano-objects are pH-responsive. Functional materials for example inorganic or metal nanoparticles are easily complexed onto the external surface, to extend both composition and microstructure of the nano-objects.

Janus colloidal particles with hierarchical structures are generated by phase separation of diblock copolymer polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and homopolymer poly(methyl methacrylate) (PMMA) binary blends in confined geometry. The dependence of their morphology on the copolymer composition, solvent selectivity, particle size, and polymer/aqueous solution interfacial property was investigated. By varying the particle/ aqueous solution interfacial property alternately, the Janus particles exhibited a reversible morphological transformation under solvent-adsorption annealing process. In addition, by introducing 3-n-pentadecyphenol (PDP) which can hydrogen bond with P4VP to form supramolecules, the structure of the Janus particles can be well tuned. Furthermore, due to the complexation of pyridine unit with Au precursor, composite Janus particles with Au nanoparticles selectively incorporated in P4VP microdomains can be easily manipulated.