Uniform “Patchy” Platelets by Seeded Heteroepitaxial Growth of Crystallizable Polymer Blends in Two Dimensions

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. ABSTRACT: Rectangular platelets formed by the self-assembly of block copolymers in selective solvents are of interest for a range of applications. Recently we showed that the seeded growth of crystallizable blends of a block copolymer and homopolymer yields well-defined, low dispersity examples of these two-dimensional (2D) structures. The key feature was the use of the same crystallizable polymer segment in the seed and blend components to enable an efficient homoepitaxial growth process. Herein we demonstrate that this 2D crystallization-driven self-assembly approach can be extended to heteropitaxial growth by the use of different crystallizable polymers with compatible crystal structures. This allows the formation of well-defined "patchy" rectangular platelets and platelet block comicelles with different core chemistries. The use of scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy provided key information on the spatial location of the components in the resulting assemblies and thereby valuable insight into the 2D heteroepitaxial growth process.

Recent progress in block copolymer crystallization

“…Changes in morphology have been shown to be sensitive to additives as well . These additives manipulated either the corona block or the core block . He and coworkers prepared micelles of poly(acrylic acid)‐ b ‐polymethylene (PAA‐ b ‐PM) with crystalline PM cores using the thermal treatment method.…”

“…The result was aggregation of rod micelles to form platelet‐like “rafts.” These resembled the truncated lozenge single crystals of PCL; however, rod‐like protrusions were observed at the (110) edges, for comparison of these two morphologies see Figure . Finally, this homopolymer additive method was extended to co‐micelle assemblies—those that contain more than one type of copolymer in the micelle—to form engineered platelet surfaces . This work also achieved co‐micelles with different crystallizable blocks via heteroepitaxial growth since the two crystals have similar lattice spacing.…”

“…In most cases, CDSA was used to form worm‐like micellar structures with crystalline cores of either PE or PFS . While the current focus of CDSA research is related to controlled micelle growth and hierarchical assembly, triblock terpolymers provide another opportunity to tailor the corona of the micelle to form “patchy” morphologies on the micelle surface . For diblock copolymers, this was achieved by mixing two copolymers .…”

Disassembly of Multicompartment Polymer Micelles in Spatial Sequence Using an Electrostatic Field and Its Application for Release in Chronological Order

“…Nevertheless, sequential or selective disassembly is still a major challenge and seldom reported . More recently, the research group of Manner reported that the self‐assembled polymer micelles can be selectively disassembled to form perforated hollow rectangular, or diamond‐shaped, platelets by selective dissolution. Herein, we reported a novel electrostatic field‐controlled disassembly of multicompartment micelles (MCPs) in spatial sequence.…”

Emergent Self‐Assembly Pathways to Multidimensional Hierarchical Assemblies using a Hetero‐Seeding Approach

“…Nevertheless,e xamples of the formation of hierarchical assemblies such as scarf and core-segmented fibers and platelets have been reported for crystallizable polymer or p-stacking molecular systems using this approach. [2,12,24] The formation of 1D and 2D heterostructures based on small organic molecules have also been reported. [34,35] Notably, in general,t he morphology of stable assemblies through seeded self-assembly is the same as those formed via unseeded self-assembly,t hat is, being independent of the added hetero-seeds even though they growo nh etero-seeds.…”