Hierarchical self-assembly offers elegant and energy-efficient bottom-up strategies for the structuring of complex materials. For block copolymers, the last decade witnessed great progress in diversifying the structural complexity of solution-based assemblies into multicompartment micelles. However, a general understanding of what governs multicompartment micelle morphologies and polydispersity, and how to manipulate their hierarchical superstructures using straightforward concepts and readily accessible polymers remains unreached. Here we demonstrate how to create homogeneous multicompartment micelles with unprecedented structural control via the intermediate pre-assembly of subunits. This directed self-assembly leads to a step-wise reduction of the degree of conformational freedom and dynamics and avoids undesirable kinetic obstacles during the structure build-up. It yields a general concept for homogeneous populations of well-defined multicompartment micelles with precisely tunable patchiness, while using simple linear ABC triblock terpolymers. We further demonstrate control over the hierarchical step-growth polymerization of multicompartment micelles into micron-scale segmented supracolloidal polymers as an example of programmable mesoscale colloidal hierarchies via well-defined patchy nanoobjects.

The concept of hierarchical bottom-up structuring commonly encountered in natural materials provides inspiration for the design of complex artificial materials with advanced functionalities. Natural processes have achieved the orchestration of multicomponent systems across many length scales with very high precision, but man-made self-assemblies still face obstacles in realizing well-defined hierarchical structures. In particle-based self-assembly, the challenge is to program symmetries and periodicities of superstructures by providing monodisperse building blocks with suitable shape anisotropy or anisotropic interaction patterns ('patches'). Irregularities in particle architecture are intolerable because they generate defects that amplify throughout the hierarchical levels. For patchy microscopic hard colloids, this challenge has been approached by using top-down methods (such as metal shading or microcontact printing), enabling molecule-like directionality during aggregation. However, both top-down procedures and particulate systems based on molecular assembly struggle to fabricate patchy particles controllably in the desired size regime (10-100 nm). Here we introduce the co-assembly of dynamic patchy nanoparticles--that is, soft patchy nanoparticles that are intrinsically self-assembled and monodisperse--as a modular approach for producing well-ordered binary and ternary supracolloidal hierarchical assemblies. We bridge up to three hierarchical levels by guiding triblock terpolymers (length scale ∼10 nm) to form soft patchy nanoparticles (20-50 nm) of different symmetries that, in combination, co-assemble into substructured, compartmentalized materials (>10 μm) with predictable and tunable nanoscale periodicities. We establish how molecular control over polymer composition programs the building block symmetries and regulates particle positioning, offering a route to well-ordered mixed mesostructures of high complexity.

The confinement of crystallizable blocks within AB or ABC microphase-separated block copolymers in the nanoscopic scale can be tailored by adequate choice of composition, molecular weight, and chemical structure. In this work we have examined the crystallization behavior of a series of AB and ABC block copolymers incorporating one or two of the following crystallizable blocks:  polyethylene, poly(ε-caprolactone), and poly(ethylene oxide). The density of confined microdomain structures (MD) within block copolymers of specific compositions, in cases where the MD are dispersed as spheres, cylinders, or any other isolated morphology, is much higher than the number of heterogeneities available in each crystallizable block. Therefore, fractionated crystallization takes place with one or several crystallization steps at decreasing temperatures. In specific cases, the clear observation of exclusive crystallization from homogeneous nuclei was obtained. The results show that, regardless of the specific morphological features of the MD, it is their vast number as compared to the number of heterogeneities present in the system that determines the fractionated character of the crystallization or in extreme cases homogeneous nucleation. The self-nucleation behavior was also found to depend on the composition of the copolymers. When the crystallizable block is confined into spheres or cylinders and exhibits homogeneous nucleation, the self-nucleation domain disappears. This is a direct consequence of the extremely high density of microdomain structures that need to be self-seeded (on the order of 1015−1016/cm3). Therefore, to increase the density of self-nuclei, the self-nucleation temperature has to be decreased to values so low that extensive partial melting is achieved, and some of the unmelted crystal fragments can be annealed, in some cases even before self-nucleation takes place.

We present a general mechanism for the solution self-assembly of crystalline-core micelles (CCMs) from triblock copolymers bearing a semicrystalline polyethylene (PE) middle block. This approach enables the production of nanoparticles with tunable dimensions and surface structures. Depending on the quality of the solvent used for PE, either spherical or worm-like CCMs can be generated in an easy and highly selective fashion from the same triblock copolymers via crystallization-induced self-assembly upon cooling. If the triblock copolymer stays molecularly dissolved at temperatures above the crystallization temperature of the PE block, worm-like CCMs with high aspect ratios are formed by a nucleation and growth process. Their length can be conveniently controlled by varying the applied crystallization temperature. If exclusively spherical micelles with an amorphous PE core are present before crystallization, confined crystallization within the cores of the preformed micelles takes place and spherical CCMs are formed. For polystyrene-block-polyethylene-block-poly(methyl methacrylate) triblock terpolymers a patch-like microphase separation of the corona is obtained for both spherical and worm-like CCMs due to the incompatibility of the PS and PMMA blocks. The structure of the patch-like corona depends on the selectivity of the employed solvent for the PS and PMMA corona blocks, whereby nonselective solvents produce a more homogeneous patch size and distribution. Annealing of the semicrystalline PE cores results in an increasingly uniform crystallite size distribution and thus core thickness of the worm-like CCMs.