Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing

Abstract

Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium’s anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal’s gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels’ optical properties that are defined by the interplay of these effects are tuned by controlling the gels’ order, which is tuned by adjusting the gels’ cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.

Structural Colors by Synergistic Birefringence and Surface Plasmon Resonance

“…With the rotating f-GNRs2 film and altering light retardation due to various CNC contents in the f-CNCs films, the flower pattern exhibited distinct, adjustable color combinations. Although sophisticated and promising manipulations of plasmonic colors have been performed via complicated micro- and nanofabrication methods, for example, the widely used physical vapor deposition to selectively coat metal layers, a general method to prepare composite polymer films with embedded nanorods with tunable morphologies and an optical mechanism is still highly desired. ,,− In this work, we presented an effective and cost-efficient method to achieve flexible color manipulation of polymer films by integrating CNCs with birefringence and GNRs exhibiting SPR. Using this method, polymer films containing aligned GNRs and/or CNCs not only showed a much wider range of adjustable structural colors than existing methods but also can be expanded to other potential nanomaterials.…”

“…A few approaches have been demonstrated to align CNCs or GNRs in polymer matrices, such as by using a magnetic field, an electric field, shear force, or templates with a well-aligned hole array. − Most of the approaches require significant energy consumption and are not compatible with polymer matrices. Although some studies attempted to coalign CNCs and GNRs in polymer matrices for structural colors, they still lack the wide tunability of structural colors. , To our best knowledge, research on the structural color control with combined birefringence of CNCs and SPR of GNRs in polymer materials based on their distinct properties has still been less explored. One major challenge is the lack of robust and compatible methods to embed ordered CNCs and GNRs in uniform polymer materials.…”

Printed aerogels: chemistry, processing, and applications

“…22 Nanocelluloses are a family of nanomaterials derived from wood pulp. 224 To date, cellulose nanofibrils (CNFs) 22,176,216,218,222,[225][226][227][228] and cellulose nanocrystals (CNCs) 181,[220][221][222]229 have been used to formulate inks for printed aerogels. CNF gels have high viscosity and shear-thinning properties as they are bonded together by strong hydrogen bonds.…”

“…Examples of crosslinking agents include silk fibroin biopolymers, 207 RF, 18 Kymene, 176,181 acrylamide (AAm) and N,N 0 -methylenebis-(acrylamide) (MBAA) with post-printing UV-gelation. 229 Examples of aerogels printed using these agents include SiO 2 , 207 GO, 18 CNC, 181,229 and CNF. 176 The gelation catalyst mainly changes the electric double layer balance of the system by catalysing the reaction or adjusting the pH value, so that the system undergoes crosslinking for gel curing.…”

Plasmonic nanomaterials with responsive polymer hydrogels for sensing and actuation

“…6D . 112 In 4D printing, the above-mentioned structuring tool provided by 3D printing is combined with the unique properties of responsive hydrogel materials to transform the shape of the object by application of an appropriate stimulus after printing. In the following chapters, the combination of responsive hydrogel materials and plasmonic structures is highlighted with recent examples of sensor and actuator applications.…”