Reversible morphological switching and deformation hysteresis in electric field mediated instability of thin elastic films

Sahoo, Sumita; Bhandaru, Nandini; Mukherjee, Rabibrata

doi:10.1039/c8sm02622j

Cited by 9 publications

(7 citation statements)

References 48 publications

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“…To illustrate just a few, chameleons achieve active and rapid color change by tuning the lattice of guanine nanocrystals, cephalopods use reversible soft tissue shape changes for camouflage, and Boquila trifoliolataa vine plant from rainforests in southern Chileis capable of complex leaf mimicry (shape, color, and orientation), potentially using communication through volatile chemicals or acoustic signals to actively imitate the leaf character of surrounding plants of other species . External stimuli to realize structural or morphological changes commonly include changes in pH, changes in temperature, mechanical deformation, exposure to chemicals, irradiation with light at specific wavelengths, − and external electric or magnetic fields. − Considering our ongoing discoveries of nanofilament shapes (morphologies) in the B4 phase of some bent-core liquid crystals (BC-LCs), we were particularly intrigued by the opportunity to alter the nanofilament shape using external stimuli other than the rate of temperature change on cooling from an isotropic liquid. Here, applying an electric field or irradiation with UV light was of particular interest.…”

Section: Introductionmentioning

confidence: 99%

Controlling the Structure and Morphology of Organic Nanofilaments Using External Stimuli

et al. 2023

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In our continuing pursuit to generate, understand, and control the morphology of organic nanofilaments formed by molecules with a bent molecular shape, we here report on two bent-core molecules specifically designed to permit a phase or morphology change upon exposure to an applied electric field or irradiation with UV light. To trigger a response to an applied electric field, conformationally rigid chiral (S,S)-2,3-difluorooctyloxy side chains were introduced, and to cause a response to UV light, an azobenzene core was incorporated into one of the arms of the rigid bent core. The phase behavior as well as structure and morphology of the formed phases and nanofilaments were analyzed using differential scanning calorimetry, cross-polarized optical microscopy, circular dichroism spectropolarimetry, scanning and transmission electron microscopy, UV–vis spectrophotometry, as well as X-ray diffraction experiments. Both bent-core molecules were characterized by the coexistence of two nanoscale morphologies, specifically helical nanofilaments (HNFs) and layered nanocylinders, prior to exposure to an external stimulus and independent of the cooling rate from the isotropic liquid. The application of an electric field triggers the disappearance of crystalline nanofilaments and instead leads to the formation of a tilted smectic liquid crystal phase for the material featuring chiral difluorinated side chains, whereas irradiation with UV light results in the disappearance of the nanocylinders and the sole formation of HNFs for the azobenzene-containing material. Combined results of this experimental study reveal that in addition to controlling the rate of cooling, applied electric fields and UV irradiation can be used to expand the toolkit for structural and morphological control of suitably designed bent-core molecule-based structures at the nanoscale.

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Section: Introductionmentioning

confidence: 99%

Controlling the Structure and Morphology of Organic Nanofilaments Using External Stimuli

et al. 2023

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“…Following this idea, many researchers studied the electric field induced dewetting of thin liquid films, theoretically and experimentally. [17][18][19][20][21][22] The advantage of studying thin film instability using an electric field is to further investigate the behavior of the instability pattern upon removing the electric field. This would help us understand the dynamic change in the interfacial and material properties during the full cycles (voltage ON and voltage OFF).…”

Section: Introductionmentioning

confidence: 99%

Reversible Dewetting of Thin Lubricating Films Underneath Aqueous Drops Using External Electric Field

Bhatt¹,

Gupta²,

Sumathi³

et al. 2022

Preprint

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The stability of thin liquid films on a surface depends on the excess free energy of the system involving various short-range and long-range interactions. In an unstable condition, thin liquid films may dewet into multiple small-sized droplets via spinodal, homogeneous, or heterogeneous nucleation process. However, if the total excess free energy of the system can be manipulated using an external stimulus, one can control the stability of thin liquid films on demand. Here, we study the reversible dewetting process of thin lubricating films underneath aqueous drops on slippery surfaces using an external electric field. Upon applying voltage, stable thin lubricating films dewet in a manner identical to the spinodal dewetting of nanometer-thick liquid films. Upon removing the applied voltage, the dewetted droplets spread, coalesce with neighboring ones, and form a uniform film again, however the time taken during rewetting is very different compared to dewetting. The characteristic features of both the dewetting and rewetting processes are present over multiple cycles. Due to the random nature of the 1

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“…17 EHD instability (i.e., electric eld-mediated instability) is not merely exploited for pattern transfer in a single-step, noncontact, versatile, and scalable manner, [18][19][20][21][22][23][24] but also provide diverse opportunities for nely tailoring the structural property by carefully selecting process parameters. [25][26][27][28][29][30][31] EHD-driven patterning is based on the phase instability behavior of a thin liquid lm under an applied out-of-plane electric eld that induces undulation of the liquid lm surface to form small patterns; this has been demonstrated experimentally via the fabrication of micro and nanoscale patterns. 17,32,33 In the EHD-driven patterning, electrostatic pressure acting on the surface of the uidic lm plays a critical role in lm destabilization.…”

Section: Introductionmentioning

confidence: 99%

Parametric scheme for rapid nanopattern replication via electrohydrodynamic instability

et al. 2021

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Reversible morphological switching and deformation hysteresis in electric field mediated instability of thin elastic films

Abstract: Reversible morphology switching by external electric field in a soft elastic film between two parallel electrodes.

Cited by 9 publications

References 48 publications

Controlling the Structure and Morphology of Organic Nanofilaments Using External Stimuli

Controlling the Structure and Morphology of Organic Nanofilaments Using External Stimuli

Reversible Dewetting of Thin Lubricating Films Underneath Aqueous Drops Using External Electric Field

Parametric scheme for rapid nanopattern replication via electrohydrodynamic instability

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