Patterning of Lyotropic Chromonic Liquid Crystals by Photoalignment with Photonic Metamasks

Peng, Chenhui; Guo, Yubing; Turiv, Taras; Jiang, M.; Wei, Qi‐Huo; Lavrentovich, Oleg D.

doi:10.1002/adma.201606112

Cited by 60 publications

(54 citation statements)

References 42 publications

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“…Earlier works to obtain large‐scale alignment follow substrate‐based approaches developed for thermotropic LCs, including alignment on polyimide (PI) substrates, rubbed glass, nanopatterned polymer films, self‐assembling monolayers, photosensitive surfaces and, very recently with photonic metamasks . In general, such substrates align thermotropics much better than LCLC solutions.…”

Section: Introductionmentioning

confidence: 99%

Fully Stable and Homogeneous Lyotropic Liquid Crystal Alignment on Anisotropic Surfaces

Asdonk¹,

Collings

Kouwer³

2017

Adv Funct Materials

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Lyotropic chromonic liquid crystals have great potential in both biosensing and optical devices due to their biocompatible nature and strong optical characteristics. These applications, however, demand a homogeneous and stable alignment on anisotropic surfaces, a challenge that, so far, has not been solved adequately. In this work, it is shown how to drastically increase the quality of in-plane alignment and stability of these liquid crystals on conventional rubbed polyimide substrates by the addition of a small amount of a nonionic surfactant. Samples with surfactant show excellent alignment that is stable for months, while control samples without surfactant show much poorer alignment that further deteriorates in days. Also, well-aligned dry films of chromonics can be prepared following this approach. It is demonstrated how to obtain high-quality alignment by controlling the concentration and the nature of the surfactant, in particular its molecular structure and hydrophilic/ lipophilic balance (HLB value) and other critical parameters are discussed. It is believed that this approach may very well be essential for advancing the applicability of these water-based, biocompatible, and often highly dichroic materials for a wide range of uses.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201701209. many new and exciting applications are emerging that require novel materials properties and new engineering methods. The last decade has seen an increasing interest in synergizing unique LC characteristics with aqueous environments, for instance, for the development of biological sensing applications, [1][2][3][4][5][6][7] (biocompatible) templates which align and manipulate (living) anisotropic materials, [8][9][10][11][12][13] and highly dichroic LCs for facile fabrication of optical elements. [14][15][16][17][18] This particular field of application requires different, water compatible materials. Excellent candidates are so-called lyotropic chromonic liquid crystals (LCLCs), which are rigid, plank-like molecules consisting of aromatic cores with hydrophilic groups on the periphery that, in water, spontaneously stack face-to-face in columnar assemblies due to π-π stacking and hydrophobic interactions. At certain concentrations and temperatures, these stacks form liquid crystalline phases [14,15] such as nematic and columnar phases. Typical members of the class of LCLCs are highly conjugated dyes that are functionalized with water-soluble (often ionic) groups. [14] The rigid, aromatic cores of LCLCs give these materials excellent optical properties, such as strong linear dichroism, high birefringence, and in some cases high absorbance in the visible range.Typically, LCLCs are applied either in closed cells where one benefits from the dynamics of the anisotropic solution or, alternatively, as a thin film after water evaporation from an anisotropic LCLC solution. In any application, however, high-quality, homogeneous, and stable macroscopic alignment is ...

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Section: Introductionmentioning

confidence: 99%

Fully Stable and Homogeneous Lyotropic Liquid Crystal Alignment on Anisotropic Surfaces

Asdonk¹,

Collings

Kouwer³

2017

Adv Funct Materials

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“…For example, up to 8 lithography steps and sometimes electron-beam lithography are needed to achieve low f-numbers, [21][22][23] diffraction-limited performance, and over 90% efficiency. [31,33,35,36] Large-sized PB lenses with low f-numbers can be made by holography photopatterning with a refractive master lens, [31] while liquid crystal PB microlenses are still limited to large f-number (>10) [32,33] and no work has been able to show diffraction-limited quality.A range of techniques have been developed in recent years to align liquid crystal molecules into arbitrary designer orientation patterns, which are either based on photoalignments using digital micromirror device (DMD), [37,38] pixel-to-pixel direct laser writing, [30] holography interference [31] and plasmonic photo patterning, [39][40][41] or based on nanostructured surfaces by using nanoimprinting [33] or atomic force microscopy scribing. [13,14,21,[29][30][31][32][33][34] The PB microlenses made of liquid crystals are particularly attractive because of their close to 100% efficiency and switchable focal lengths.…”

mentioning

confidence: 99%

“…A range of techniques have been developed in recent years to align liquid crystal molecules into arbitrary designer orientation patterns, which are either based on photoalignments using digital micromirror device (DMD), [37,38] pixel-to-pixel direct laser writing, [30] holography interference [31] and plasmonic photo patterning, [39][40][41] or based on nanostructured surfaces by using nanoimprinting [33] or atomic force microscopy scribing. [42] These techniques have enabled various applications and research ranging from optical devices to programmable origami.…”

mentioning

confidence: 99%

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Jiang

Guo

et al. 2019

Advanced Materials

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For example, phase profiles required for lensing can be realized by sculpturing dielectric substrates with discretized steps or sloped ridges through photo lithography and reactive ion etching. [18][19][20] These lithography processes make diffractive microlenses more tailorable than refractive microlenses in terms of filling factor and low f-number. However, to achieve high performances, very complex fabrication processes are needed. For example, up to 8 lithography steps and sometimes electron-beam lithography are needed to achieve low f-numbers, [21][22][23] diffraction-limited performance, and over 90% efficiency. [19,[24][25][26] The phase profiles desired for lensing can also be realized with the Pancharatnam-Berry (PB) phases [27,28] by using birefringent materials or metasurfaces with spatially variant optical axes. [13,14,21,[29][30][31][32][33][34] The PB microlenses made of liquid crystals are particularly attractive because of their close to 100% efficiency and switchable focal lengths. [31,33,35,36] Large-sized PB lenses with low f-numbers can be made by holography photopatterning with a refractive master lens, [31] while liquid crystal PB microlenses are still limited to large f-number (>10) [32,33] and no work has been able to show diffraction-limited quality.A range of techniques have been developed in recent years to align liquid crystal molecules into arbitrary designer orientation patterns, which are either based on photoalignments using digital micromirror device (DMD), [37,38] pixel-to-pixel direct laser writing, [30] holography interference [31] and plasmonic photo patterning, [39][40][41] or based on nanostructured surfaces by using nanoimprinting [33] or atomic force microscopy scribing. [42] These techniques have enabled various applications and research ranging from optical devices to programmable origami. [30,33,37,38,[43][44][45][46][47] Here, we show that high-quality microlenses based on PB phases can be designed and made with liquid crystal polymers by using a plasmonic photopatterning technique. The plasmonic photopatterning technique allows for arbitrary molecular orientations encoded in designs of so-called plasmonic metamasks. We designed and fabricated microlenses with a set of focal lengths and f-numbers to test the quality and resolution limit of the plasmonic photopatterning technique. As discussed later, the microlenses with f-number down to 2 requires 1.5 µm of smallest molecular pitches.Microlenses are desired by a wide range of industrial applications while it is always challenging to make them with diffraction-limited quality. Here, it is shown that high-quality microlenses based on Pancharatnam-Berry (PB) phases can be made with liquid crystal polymers by using a plasmonic photopatterning technique. Based on the generalized Snell's law for the PB phases, PB microlenses with a range of focal lengths and f-numbers are designed and fabricated and their point-spread functions and ability to image micrometer-sized particles are carefully characterized. The results show that...

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“…Previous studies have demonstrated that periodic surface wrinkles can only be generated on top of a cholesteric liquid crystal under harsh conditions, 26,27 meanwhile the alignment direction of liquid crystal molecules can be patterned into complex spatially-varying structures with high precision. 28,29 Thus, it will be attractive to develop a simple means of preparing patterned cholesteric CNC films with controllable alignment and photonic properties.…”

Section: Introductionmentioning

confidence: 99%

Printing Flowers? Custom-Tailored Photonic Cellulose Films with Engineered Surface Topography

Chu

Camposeo

Vilensky

et al. 2019

Matter

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Wrought by nature's wondrous hand, surface topographies are discovered on all length scales in living creatures and serve a variety of functions. Inspired by floral striations, here we developed a scalable means of fabricating custom-tailored photonic cellulose films that contained both cholesteric organization and microscopic wrinkly surface topography. Free-standing films were prepared by molding cellulose nanocrystal ink onto an oriented wrinkled template through evaporation-assisted nanoimprinting lithography, yielding morphology-induced light scattering at a short wavelength as well as optically tunable structural color derived from the helical cellulose matrix. As a result, the interplay between the two photonic structures, grating-like surface and chiral bulk, led to selective scattering of circularly polarized light with specific handedness. Moreover, the wrinkled surface relief on cholesteric cellulose films could be precisely controlled, enabling engineered printing of microscopic patterned images.

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Patterning of Lyotropic Chromonic Liquid Crystals by Photoalignment with Photonic Metamasks

Cited by 60 publications

References 42 publications

Fully Stable and Homogeneous Lyotropic Liquid Crystal Alignment on Anisotropic Surfaces

Fully Stable and Homogeneous Lyotropic Liquid Crystal Alignment on Anisotropic Surfaces

Low f‐Number Diffraction‐Limited Pancharatnam–Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers

Printing Flowers? Custom-Tailored Photonic Cellulose Films with Engineered Surface Topography

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