Fabrication of pixelated liquid crystal nanostructures employing the contact line instabilities of droplets

Ravi, Bolleddu; Bhattacharjee, Mitradip; Ghosh, Abir; Bandyopadhyay, Dipankar

doi:10.1039/c8nr08400a

Cited by 6 publications

(3 citation statements)

References 71 publications

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“…25,26 Some research have also been done on the contact line instability of LC drop on solid substrates. [27][28][29][30] Herminghaus et al have also reported instantaneous room temperature dewetting of 5AB 4 (which undergoes direct phase transition from crystalline phase to isotropic phase at T z 10 C) thin lms transferred from an LB trough to a silicon substrate. Clear signatures of both nucleated and spinodal dewetting were observed during the dewetting of the lm.…”

Section: Introductionmentioning

confidence: 99%

Phase transition and dewetting of a 5CB liquid crystal thin film on a topographically patterned substrate

Dhara

Mukherjee

2019

RSC Adv.

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Section: Introductionmentioning

confidence: 99%

Phase transition and dewetting of a 5CB liquid crystal thin film on a topographically patterned substrate

Dhara

Mukherjee

2019

RSC Adv.

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“…28 A few recent studies uncover that the same can also be achieved under a solvent exposure at room temperature. 29 Subsequently, self-organization 30 under long-range interactions and spin dewetting 31 of an LC film on a patterned surface are the other alternative routes leading to an ordered array of LC droplets. Once such droplet arrays are formed, the transmission of polarized light rays through such LC droplets can indeed be controlled through a solvent exposure.…”

Section: Introductionmentioning

confidence: 99%

Self-Organized Liquid Crystal Droplets as Phototunable Softmasks

Thakur

Dasmahapatra

Bandyopadhyay

2021

ACS Appl. Mater. Interfaces

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A single-step self-organized pathway is harnessed to generate large-area and high-density liquid-crystal (LC) microdroplets via rapid spreading of an LC-laden volatile liquid film on an aqueous surfactant bath. The surfactant loading on the water bath and LC loading in the solvent fluid help in tuning the size, periodicity, and ordering of LC microdroplets. Remarkably, the experiments reveal a transition from a spinodal to heterogeneous nucleation pathway of dewetting when the surfactant loading is modulated from below to beyond the critical micellar concentration in the aqueous phase. In the process, a host of unprecedented drop formation modes, such as dewetting and contact-line instability, random ejection, and "fire cracker" toroid splitting, have been uncovered. Subsequently, the LC microdroplets on the air−water interface are employed as photomasks suitable for soft-photolithography applications. Such masks help in the decoration of a host of mesoscale three-dimensional features on the films of photoresists when photons are guided through the LC droplets. In such a scenario, phase transition of LC droplets under solvent vapor annealing is employed to control the movement of photons through drops and subsequently modulate the light exposure on the photoresist surface. Such a simple softphotolithography setup leads to an array of flattened droplets on a positive resist, while donut features are observed on the negative tone. Remarkably, the orientation of nematogens within 4-cyano-4′-pentylbiphenyl droplets and at the three-phase contact-line provides additional handles in controlling the transmission of photons, which facilitates such a unique pattern formation. A number of low-cost and simple strategies are also discussed to order such soft-photolithography patterns. Importantly, with a minor modification to the same experimental setup, we could also measure the variation in the order parameter of the LC droplet during its phase transitions from the nematic to isotropic state.

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“…Liquid marbles can also interact with light to create optically responsive reactors , or light-driven delivery vehicles. , We hypothesize that compound lenses inspired by the mosquito eye can be created by combining the mobility and stability of liquid marbles with the monodispersity and large-scale production of droplet-based microfluidic devices. In addition, a chemically patterned substrate can host and localize multiple sessile droplets where each could serve as the hemispherical dome structures of compound lenses, leading to a scalable process. − …”

Section: Introductionmentioning

confidence: 99%

Multifunctional Liquid Marble Compound Lenses

Shin

Huang

Neibloom

et al. 2019

ACS Appl. Mater. Interfaces

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Mosquito compound eyes are elaborate multifunctional hierarchical structures. The presence of ordered curved features spanning length scales of nanometers to millimeters provides the mosquito eye with a wide field of view, an infinite depth of field, and antifogging properties. Developing bio-inspired compound lenses is challenging because of the need to mimic all characteristic curvatures along with their functionalities. Herein, we show how the curvature inherent to nanoparticles, emulsion droplets, and liquid marbles can be employed to mimic the hierarchical structure and functionality of mosquito compound eyes. At the nanometer to micrometer length scale we employ nanoparticle-stabilized emulsion droplets of photocurable oil to form microlenses with nanoscale surface features. After polymerization, the microlenses form a monolayer on an oil droplet to create an optically clear, millimeter scale, liquid marble that functions as a compound lens. We characterize the optical and surface properties of the compound lenses and find that they reproduce the functionality of the mosquito eye. Additionally, we exploit the mobility and reconfigurability of liquid marbles to create arrays (centimeter scale) of compound lenses and other types of functional lenses such as the Janus lens that magnifies the image acquired by the compound lens. Simple and scalable methods to create compound lenses could aid in the development of miniaturized advanced vision systems.

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Fabrication of pixelated liquid crystal nanostructures employing the contact line instabilities of droplets

Abstract: A single-step room-temperature fabrication method is presented to develop a collection of ordered LC micro-/nanodroplets over a large surface area.

Cited by 6 publications

References 71 publications

Phase transition and dewetting of a 5CB liquid crystal thin film on a topographically patterned substrate

Phase transition and dewetting of a 5CB liquid crystal thin film on a topographically patterned substrate

Self-Organized Liquid Crystal Droplets as Phototunable Softmasks

Multifunctional Liquid Marble Compound Lenses

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