Robust Full‐Spectral Color Tuning of Photonic Colloids

Abstract

structure periodicity, thereby enabling a photonic response across the entire visible spectrum. [1][2][3] Among these engineered systems, photonic pigments are of particular interest, as they offer pure and brilliant coloration free from chemical-or photo-bleaching. Hence, such pigments represent a central goal in the future developments of paints, cosmetics, and displays. [4][5][6][7][8] So far, most efforts to develop structurally colored pigments have been based on confining the self-assembly of colloidal particles [9,10] or liquid crystals [11] in specific geometries. However, significant limitations of synthesizing large quantities of photonic pigments based on these amorphous arrays include the lack of control over incoherent and multiple scattering and the difficulty in producing pigments with distinct colors across the entire visible spectrum. [12] A promising alternative is the 3D confined self-assembly of block copolymers (BCPs) in emulsion droplets, which, in principle, represents a user-friendly and scalable procedure to fabricate polymer-based PhCs with vivid coloration spanning the entire visible spectrum. [13,14] BCPs exhibit rapid assembly kinetics in solution, macroscopic ordering into self-assembled morphologies, tolerance to high loading of functional additives, and the possibility to manipulate the produced coloration simply by tuning the polymer chain length and structure. [15,16] Several efforts employing BCPs focused on fabricating planar multilayer structures that show brilliant but iridescent coloration, [17][18][19][20][21] while more recent studies showed that linear symmetric BCPs can form a concentric lamellar structure (i.e., onion-like microspheres) within spherical confinement in emulsion droplets, resulting in photonic multilayered particles. [22][23][24][25][26] These ordered systems comprise two blocks that form lamellar domains, each having a distinct refractive index, and show strong reflection when Bragg reflection conditions are satisfied, thus holding promise as non-iridescent photonic pigments due to their spherical shape. [15,24] Controlling the optical properties of such photonic pigments generally requires the synthesis of long BCPs whose self-assembly kinetic is slowed by their high molecular weight. Domain spacings beyond 100 nm can be achieved, for example, by using bottle-brush BCPs as their non-linear chain architecture with grafted side chains limits chain entanglement thereby accelerating structural reorganization. [27,28] Alternatively, Creation of color through photonic morphologies manufactured by molecular self-assembly is a promising approach, but the complexity and lack of robustness of the fabrication processes have limited their technical exploitation. Here, it is shown that photonic spheres with full-color tuning across the entire visible spectrum can be readily and reliably achieved by the emulsification of solutions containing a block copolymer (BCP) and two swelling additives. Solvent diffusion out of the emulsion droplets gives rise to 20-150 µm-size...

Stabilizing oil–oil interfaces with mixed-shell polymeric nanoparticles prepared via PISA and the grafting combination

“…145 °C. 62 For PMMA 24 –P4VP x micelles initially dispersed in [Bmim][PF 6 ], the cores of M 24 V x micelles were frozen owing to low CMC and high core block T g . 58 For the frozen micelles, the exchange between unimers and micelles was very slow.…”

Controlled Growth of Large SiO2 Shells onto Semiconductor Colloidal Nanocrystals: A Pathway Toward Photonic Integration

“…To envision a future colloidal integration of the two systems, NCs must be enlarged in size maintaining their characteristic emission properties. Silicon oxide shells (SiO 2 ) are a promising candidate to enable such approach as procedures to growth them on top of NCs are already available in literature, enabling an inert shell with relatively low impact on the optical properties of the embedded nanocrystal. − Such SiO 2 shells can be employed as a positive resist for the integration of photonic components via nanofabrication or as a scaffold for building multilayer structures similar to distributed Bragg reflectors . The only detrimental property of enclosing NCs into a SiO 2 shell is the electrical insulating nature of the latter, which, in turn, prevents the electrical driving of the embedded semiconductor emitter.…”

“… 10 − 12 Such SiO 2 shells can be employed as a positive resist for the integration of photonic components via nanofabrication or as a scaffold for building multilayer structures similar to distributed Bragg reflectors. 13 The only detrimental property of enclosing NCs into a SiO 2 shell is the electrical insulating nature of the latter, which, in turn, prevents the electrical driving of the embedded semiconductor emitter. A notable example of light-control integration through SiO 2 shells is the work from Ji et al., where the authors were able to fabricate a plasmon microcavity directly onto a NC and enhance the emission rate.…”

Beyond Labeling: Hybrid Planar Photonic Crystals for Anti-tampering Detection of Amines

“…26 Indeed, thanks to a relatively low dielectric contrast among polymers, they can be designed to have narrow PBGs. 26 Also, polymer multilayers can be grown using various simple and fast techniques, such as copolymer self-assembly, 34,35 dip coating, 36 spin coating, 37 and even coextrusion, 25 an industrial method that makes them compatible with current packaging production. 25,38 In this context, we propose a hybrid polymer−inorganic DBR for the detection of biogenic amines in the vapor phase.…”

“…Also, polymer multilayers can be grown using various simple and fast techniques, such as copolymer self-assembly, , dip coating, spin coating, and even coextrusion, an industrial method that makes them compatible with current packaging production. , …”