Exploiting cellular convection in a thick liquid layer to pattern a thin polymer film

Nejati, Iman; Dietzel, Mathias; Hardt, Steffen

doi:10.1063/1.4940366

Cited by 13 publications

(4 citation statements)

References 29 publications

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“…12(c)]. 129 This is very similar to the work of Xu et al discussed above, though extended to the 100s of lm scale [ Fig. 12(d)].…”

Section: Reviewsupporting

confidence: 81%

“…Recently, to extend patterning effect to microscale features in thin films, Nejati et al performed transverse ZA on liquid photoresist that was contained under a sub‐

normalm normalm

thickness oil layer to induce MB convection [Fig. (c)] . This is very similar to the work of Xu et al discussed above, though extended to the 100s of μ

m

scale [Fig.…”

Section: Introductionmentioning

confidence: 99%

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Thermocapillary approaches to the deliberate patterning of polymers

Singer

2017

J Polym Sci B Polym Phys

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The phenomenon of thermocapillarity, the response of fluids to thermal gradients due to thermal alteration of their surface tension, was first reported over a century ago. Since then, research has focused generally on either the fundamentals or mitigation of this effect during the processing of materials. Only in the past two decades has the deliberate use of thermocapillary forces for the patterning of polymers been actively pursued, either for the ordering of internal structure or the introduction of topographic features. This review seeks to highlight this work and to identify directions for further investigation. In particular, while thermocapillary forces are often inextricably bound to other mechanisms, there are emerging directions in the deliberate coupling of forces to improve the capabilities of each mechanism. Further, the applications of thermocapillary patterning to polymer-nanoparticle composites has recently provided another promising route to active architectures.

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“…12(c)]. 129 This is very similar to the work of Xu et al discussed above, though extended to the 100s of lm scale [ Fig. 12(d)].…”

Section: Reviewsupporting

confidence: 81%

“…Recently, to extend patterning effect to microscale features in thin films, Nejati et al performed transverse ZA on liquid photoresist that was contained under a sub‐

normalm normalm

thickness oil layer to induce MB convection [Fig. (c)] . This is very similar to the work of Xu et al discussed above, though extended to the 100s of μ

m

scale [Fig.…”

Section: Introductionmentioning

confidence: 99%

Thermocapillary approaches to the deliberate patterning of polymers

Singer

2017

J Polym Sci B Polym Phys

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“…Furthermore, incorporating disjoining pressure into the model would provide insight into how substrate wettability can be used to enhance feature heights in bilayer or multilayer PMP. The model could also be extended to account for thermal Marangoni flows induced by temperature gradients. − If such gradients are imposed on the top film, this would represent an additional way to pattern polymer bilayers.…”

Section: Discussionmentioning

confidence: 99%

Photochemically Induced Marangoni Patterning of Polymer Bilayers

2023

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Surface-tension gradients created along a polymer film by patterned photochemical reactions are a powerful tool for creating surface topography. Here, we use mathematical modeling to explore a strategy for patterning photochemically inactive polymers by coupling a light-sensitive and light-insensitive polymer to form a polymer bilayer. The light-sensitive polymer forms the top layer, and the most dominant surface-tension gradients are introduced at the interface between this layer and air. Lubrication theory is used to derive nonlinear partial differential equations describing the heights of each layer, and linear analysis and nonlinear simulations are performed to characterize interface dynamics. Patterns form at both the polymer−air and polymer−polymer interfaces at early thermal annealing times as a result of Marangoni stresses but decay on prolonged thermal annealing as a result of the dissipative mechanisms of capillary leveling and photoproduct diffusion, thus setting a limit to the maximum individual layer deformation. Simulations also show that the bottom-layer features can remain "trapped", i.e., exhibit no significant decay, even while the top layer topography has dissipated. We study the effects of two key parameters, the initial thickness ratio and the viscosity ratio of the two polymers, on the maximum deformation attained in the bottom layer and the time taken to attain this deformation. We identify regions of parameter space where the maximum bottom-layer deformation is enhanced and the attainment time is reduced. Overall, our study provides guidelines for designing processes to pattern photochemically inactive polymers and create interfacial topography in polymer bilayers.

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“…Numerous studies have considered the use of this approach for patterning thin polymer films (Singer, 2017). In particular, Nejati et al (Nejati, Dietzel, & Hardt, 2016) leveraged the Bénard-Marangoni instability to drive short-wavelength deformation in a polymer film, yet their approach was limited to periodic structures. McLeod and Troian demonstrated deformations of nanoscale films using temperature-controlled structural elements brought in close proximity to the film, but this required the mechanical fabrication of conducting metal structures for each desired deformation (McLeod, Liu, & Troian, 2011).…”

Section: Introductionmentioning

confidence: 99%

Programmable thermocapillary shaping of thin liquid films

Eshel

Frumkin

Nice

et al. 2022

Flow

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We present a method that leverages projected light patterns as a mechanism for freeform deformation of a thin liquid film via the thermocapillary effect. We developed a closed-form solution for the inverse problem of the thin-film evolution equation, allowing us to obtain the projection pattern required in order to achieve a desired topography. We experimentally implement the method using a computer controlled light projector, which illuminates any desired pattern onto the bottom of a fluidic chamber patterned with heat–absorbing metal pads. The resulting heat map induces surface tension gradients in the liquid–air interface, giving rise to thermocapillary flow that deforms the liquid surface. If a polymer is used for the liquid film, it can then be photocured to yield a solid device. Based on the inverse-problem solutions and using this system, we demonstrate the fabrication of several diffractive optical elements, including phase masks for extended depth of field imaging, and for three-dimensional localization microscopy. The entire process, from projection to solidification, is completed in less than five minutes, and yields a sub-nanometric surface quality without any post-processing.

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Exploiting cellular convection in a thick liquid layer to pattern a thin polymer film

Cited by 13 publications

References 29 publications

Thermocapillary approaches to the deliberate patterning of polymers

Thermocapillary approaches to the deliberate patterning of polymers

Photochemically Induced Marangoni Patterning of Polymer Bilayers

Programmable thermocapillary shaping of thin liquid films

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