Thermally Tunable Metallodielectric Photonic Crystals from the Self‐Assembly of Brush Block Copolymers and Gold Nanoparticles

Abstract

COMMUNICATIONthis system for the fabrication of metamaterials that have useful metallic photonic behaviors such as strong localized surface plasmon resonance (LSPR), and the tuning range of its PBG was also limited (560-640 nm).In this work, we demonstrate a simple strategy for rapid and scalable fabrication of well-ordered metallodielectric 1D PhCs using amphiphilic brush BCPs as the templates and H-bonding as a driving force for the selective incorporation of gold NPs into hydrophilic domains (see Figure 1 ). We express the concentrations of the gold NPs as the weight percentage (wt%) of the nanocomposites based on the mass of the NP core and ligand shell, while the wt% of the NP core (Au%) was determined using the thermogravimetric analysis (TGA) of the composite and refl ects the Au metal content of the composite. The content of the gold NPs of ≈2 nm in a core diameter was up to 67.2 wt% (Au% = 48.4 wt%), corresponding to 80.4 wt% of the gold NPs (Au% = 58.1 wt%) in the hydrophilic domain. By varying the gold NP loading quantity or the molecular weight of the brush BCP, highly ordered metallodielectric structures with the domain spacing controlled from 120 to 260 nm were readily created resulting in widely tunable PBGs from the visible to near-IR region (458-1010 nm). Moreover, the PBG is also tunable via thermally induced ripening of the NPs, which infl uences their size as well as their distribution (see Figure 1 ). A network structure of gold NPs with diameters greater than 10 nm was formed after thermal annealing leading to greatly increased conductivity and higher effective refractive index of the gold NP layer. The optical properties of the metallodielectric PhCs were signifi cantly infl uenced by the network structure of gold NPs, which is tunable simply through the variation of annealing time. Numerical modeling using transfer matrix methods was employed to quantify the optical characteristics infl uenced by the effective conductivity of the gold NP network and showed a good agreement with the experimental results.Recently, chemists have made a signifi cant progress in design and synthesis of brush BCPs which show substantially reduced polymer chain entanglements relative to their linear analogues. This enables rapid self-assembly to yield nanostructures with domain sizes on the order of several hundreds of nanometers. [19][20][21][22][23][24][25] Introducing metal NPs into the large microdomains of phase-separated brush BCPs is of great interest from both fundamental research and application viewpoints. In our work, the brush BCPs were well-defi ned (polynorbornene-g -polystyrene)-b -(polynorbornene-g -poly(ethylene oxide)) block copolymers ((PNB-PS 3.5k ) n -b -(PNB-PEO 2k ) m ) synthesized by sequential ring opening metathesis polymerization (ROMP) (see the Supporting Information for details). The molecular weight of the Photonic crystals (PhCs) prepared via the self-assembly of block copolymers (BCPs) offer new opportunities for simple fabrication of fl exible photonic devices or coatings in an in...

Improving Faraday rotation performance with block copolymer and FePt nanoparticle magneto-optical composite

“…Strong NP/BCP interactions have been shown to selectively integrate functional NPs into specific domains with desired size, filling fractions, and building block directions [64][65][66][67][68][69][70]. Resulting hybrid materials, with improved electric and optical properties, have been utilized in organic field effect transistor [71] and polymeric Bragg mirrors [72,73].…”

Block Copolymer Nanocomposites with High Refractive Index Contrast for One-Step Photonics

“…[46][47][48][49][50][51][52]55,58 The BBCPs are well-defined (polynorbornene-graft-poly(tert-butyl acrylate))-block-(polynorbornene-graft-poly(ethylene oxide)) BCPs ((PNB-PtBA 8.2k ) n -b-(PNB-PEO 5k ) m ) synthesized by sequential ring-opening metathesis polymerization (ROMP). The detailed synthetic procedures were reported in our recent publication.…”

“…[53][54] Recently, we reported photonic nanocomposites containing high concentrations of gold NPs from the self-assembly of (polynorbornene-graft-poly(styrene))-block-(polynorbornene-graft-poly(ethylene oxide)) BBCPs ((PNB-PS 3.5k ) n -b-(PNB-PEO 2k ) m ). 55 Although the metallodielectric structure showed interesting photonic behavior, the absorption of the visible light by the metal component leads to a limited reflection. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 5 Here we address these limitations via the self-assembly of BBCP-based nanocomposites stabilized by strong enthalpic interactions between the BBCP matrix and zirconium oxide (ZrO 2 ) NPs, which are transparent to visible light (see scheme 1).…”

Synthesis and Applications of Compartmentalised Molecular Polymer Brushes

“…When selecting building blocks for self-assembly,m olecular brushes may offer easier tunability than their linear analogues,a st he lamellar spacing can be simply adjusted by achange in the brush grafting density (but retaining the same backbone dimensions). [53] This highly combinatorial approach to tuning the optical properties of polymer films demonstrates the versatility of molecular brushes in the fabrication of photonic coatings.G iven their unique phase separation, block-type brushes may also be self-assembled in "confinement" (e.g.e mulsion droplets) [54] to yield (nano)- Figure 5. [52] Increases in the degree of polymerisation of the brush backbone led to increasing domain spacing in the respective thin films,w ith ar emarkable near-linear relationship observed.…”

“…gold nanoparticles;F igure 5G,H). [53] This highly combinatorial approach to tuning the optical properties of polymer films demonstrates the versatility of molecular brushes in the fabrication of photonic coatings.G iven their unique phase separation, block-type brushes may also be self-assembled in "confinement" (e.g.e mulsion droplets) [54] to yield (nano)- Figure 5. A) The segregation of side chains along the z axis yields much larger lamellar structures (and with ahigher degree of organisation) than in arandom configuration, as measured by SAXS on B) random copolymer brushes and on their C) block analogues.…”