To investigate whether diblock copolymers with substantial distributions of molecular weight and composition can self-assemble into highly regular microdomain structures, we examine the morphologies of polystyrene-b-poly(acrylic acid), diblock copolymers (PS-PAA) synthesized by controlled radical polymerization in emulsion. Despite diblock polydispersity indices of ca. 2, solvent-cast films of these diblocks, as well as their blends with PS homopolymer of low molecular weight, exhibit well-ordered lamellar or hexagonally packed cylindrical morphologies in the midrange of composition, as shown by small-angle X-ray scattering and transmission electron microscopy. In several specimens, well-ordered regions of lamellae and cylinders appear to coexist. Films of very asymmetric diblocks or blends exhibit spherical microdomains without lattice order.

Plasmonic nanoparticles, particularly gold nanoparticles (GNPs) hold a great potential as structural and functional building blocks for three-dimensional (3D) nanoarchitectures with specific optical applications. However, a rational control of their assembly into nanoscale superstructures with defined positioning and overall arrangement still remains challenging. Herein, we propose a solution to this challenge by using as building blocks: (1) nanometric silica helices with tunable handedness and sizes as a matrix and (2) GNPs with diameter varying from 4 to 10 nm to prepare a collection of helical GNPs superstructures (called Goldhelices hereafter). These nanomaterials exhibit well-defined arrangement of GNPs following the helicity of the silica template. Strong chiroptical activity is evidenced by circular dichroism (CD) spectroscopy at the wavelength of the surface plasmon resonance (SPR) of the GNPs with a anisotropy factor (g-factor) of the order of 1 × 10, i.e., 10-fold larger than what is typically reported in the literature. Such CD signals were simulated using a coupled dipole method which fit very well the experimental data. The measured signals are 1-2 orders of magnitude lower than the simulated signals, which is explained by the disordered GNPs grafting, the polydispersity of the GNPs, and the dimension of the nanohelices. These Goldhelices based on inorganic templates are much more robust than previously reported organic-based chiroptical nanostructures, making them good candidates for complex hierarchical organization, providing a promising approach for light management and benefits in applications such as circular polarizers, chiral metamaterials, or chiral sensing in the visible range.

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