Polymer grafting density critically influences the self-assembly of polymer-grafted nanoparticles, yet the low grafting density regime remains underexplored. Here, we investigate the thin-film self-assembly of bottlebrush polymer-grafted core/shell nanoparticles (BPGNPs) under quasi-2D confinement at near-zero grafting densities through coarse-grained molecular dynamics (CGMD). The NP core is modeled using a hard-core/soft-shoulder (HCSS) potential, and it is compared against Weeks–Chandler–Andersen (WCA) potential. While the phase behaviors of both models are well-known, the distinct phase behaviors of both models persist even with polymer grafting offering additional room for tunability. Unlike sufficiently high grafting density or bare nanoparticles (NPs), grafting a single bottlebrush polymer breaks the rotational symmetry. The resulting structural polarity of grafted NPs can be precisely controlled through bottlebrush design parameters. We demonstrate that enhanced structural polarity stabilizes specific ordered phases, enabling precise control over self-assembled morphologies such as hexagonal lattices, square lattices, and linear clusters. Lastly, we explore the impact of synthesis-induced heterogeneity by introducing bare NPs, dual-polymer-grafted particles, and unconjugated polymers as minor species, providing insights into morphological stability under realistic grafting conditions. This work advances our understanding of BPGNP self-assembly in the near-zero grafting density regime and establishes design principles for functional nanotechnology applications.
We report a new bottlebrush copolymer (BBCP) ligand design as robust patches for gold nanoparticles (Au NPs) to construct a rigid template guiding heterometal deposition on the surface. Given the spatial congestion of the side chains, the BBCP rapidly forms dense and stationary patches on Au NPs and effectively blocks additional metal deposition. Reducing solvent quality varies the phase segregation of the BBCP and subsequently restricts metal deposition to specific locations, fabricating diverse bimetallic heterostructures. The resulting morphology exhibits a unique orientation-dependent scattering property that thermodynamic configuration cannot achieve.
A hierarchically porous polymer (HPP) consisting of micropores (∼1 nm) within a 3D continuous mesoporous wall (∼15 nm) was used to support well-defined Pt nanoparticles (2 nm in diameter) as a heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction in the liquid phase. The ligand-capped nanoparticles were loaded into the polymer and treated with plasma to expose the active surface. The dual porosity was essential: the block polymer-templated mesopores provided the reactants facile access to the nanoparticle center, which was firmly immobilized by the microporous surface. Compared to inorganic mesoporous silica supports, which are intrinsically susceptible to basic hydrolysis, the Pt-HPP featured higher activity for all halide leaving groups, even in green solvents, as well as excellent recyclability. Only 5% decrease in activity was observed after 10 cycles. Pt-HPP was one of the most active heterogeneous catalysts for aryl chloride substrates compared to literature Pt or Pd examples.
We report the synthesis of thiopropionic acid-functionalized polymethacrylate-b-polystyrene (PMATA-b-PS) as a template for patterning Ag nanoarrays. Reversible addition-fragmentation chain transfer (RAFT) polymerization of silyl-protected propagyl methacrylate followed by chain extension with styrene produced a block copolymer precursor. Deprotection of the trimethylsilyl group and subsequent thiol-yne reaction afforded the target, PMATA-b-PS. While the entire series of the precursor was in the disordered phase, microphase separated morphologies were identified from PMATA-b-PS, indicating an increased interaction parameter (χ) as a result of introducing the acid groups. As a preliminary result, we show that an Ag nanoparticle array can be fabricated by selectively associating Ag+ ions to the PMATA cylinders in the thin film of PMATA-b-PS and removing the organic polymer layer by oxygen plasma treatment.
Metal catalysts are generally supported on hard inorganic materials because of their high thermochemical stabilities. Here, we support Pd catalysts on a thermochemically stable but “soft” engineering plastic, polyphenylene sulfide (PPS), for acetylene partial hydrogenation. Near the glass transition temperature (~353 K), the mobile PPS chains cover the entire surface of Pd particles via strong metal-polymer interactions. The Pd-PPS interface enables H2 activation only in the presence of acetylene that has a strong binding affinity to Pd and thus can disturb the Pd-PPS interface. Once acetylene is hydrogenated to weakly binding ethylene, re-adsorption of PPS on the Pd surface repels ethylene before it is further hydrogenated to ethane. The Pd-PPS interaction enables selective partial hydrogenation of acetylene to ethylene even in an ethylene-rich stream and suppresses catalyst deactivation due to coke formation. The results manifest the unique possibility of harnessing dynamic metal-polymer interaction for designing chemoselective and long-lived catalysts.
