Controlled Fabrication of Polypyrrole Surfaces with Overhang Structures by Colloidal Templating

Akerboom, Sabine; Pujari, Sidharam P.; Turak, Ayse; Kamperman, Marleen

doi:10.1021/acsami.5b03903

Cited by 15 publications

(25 citation statements)

References 71 publications

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“…Most inverse opals in experiments, which are fabricated using sacrificial particles, have cavities of hundreds of nanometres or more [3,10,42–44]. These sizes are much larger than the cavities considered in the current calculations.…”

Section: Resultsmentioning

confidence: 97%

“…We consider here the case that the cut-off fraction is c = 0.9. This c -value is chosen to mimic the inverse opal in [10]. The distance between the cavities was set to s = d − 1 (cavities are connected to each other by small openings).…”

Section: Resultsmentioning

confidence: 99%

“…An interesting case is the wetting of an inverse opal of polypyrrole [10]. The inverse opal of polypyrrole does not have a smooth top surface.…”

Section: Resultsmentioning

confidence: 99%

“…A famous example is the surface of a lotus leaf: Although the material of the leaf is hydrophilic (contact angle on a smooth substrate θ Y < 90°), the structured surface is hydrophobic (apparent contact angle θ > 90°) [1]. Recently, different surface structures have been designed and fabricated from hydrophilic materials that show hydrophobic contact angles [2–10]. An example is an inverse opal as schematically shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Three-gradient regular solution model for simple liquids wetting complex surface topologies

Akerboom

Kamperman

Leermakers

2016

Beilstein J. Nanotechnol.

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SummaryWe use regular solution theory and implement a three-gradient model for a liquid/vapour system in contact with a complex surface topology to study the shape of a liquid drop in advancing and receding wetting scenarios. More specifically, we study droplets on an inverse opal: spherical cavities in a hexagonal pattern. In line with experimental data, we find that the surface may switch from hydrophilic (contact angle on a smooth surface θY < 90°) to hydrophobic (effective advancing contact angle θ > 90°). Both the Wenzel wetting state, that is cavities under the liquid are filled, as well as the Cassie–Baxter wetting state, that is air entrapment in the cavities under the liquid, were observed using our approach, without a discontinuity in the water front shape or in the water advancing contact angle θ. Therefore, air entrapment cannot be the main reason why the contact angle θ for an advancing water front varies. Rather, the contact line is pinned and curved due to the surface structures, inducing curvature perpendicular to the plane in which the contact angle θ is observed, and the contact line does not move in a continuous way, but via depinning transitions. The pinning is not limited to kinks in the surface with angles θkink smaller than the angle θY. Even for θkink > θY, contact line pinning is found. Therefore, the full 3D-structure of the inverse opal, rather than a simple parameter such as the wetting state or θkink, determines the final observed contact angle.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

“…An interesting case is the wetting of an inverse opal of polypyrrole [10]. The inverse opal of polypyrrole does not have a smooth top surface.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Three-gradient regular solution model for simple liquids wetting complex surface topologies

Akerboom

Kamperman

Leermakers

2016

Beilstein J. Nanotechnol.

Self Cite

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“…Second, the close-cell structure provides mechanical robustness since all features are interconnected and covalently bond to the substrate, rendering them much more resistant to abrasion and mechanical damage. 35 Finally, the inversion of the convex surface structure of the colloids provides concave surface features with overhang, 36 a prerequisite for controlling wettability of the surface features.…”

Section: -32mentioning

confidence: 99%

Tailoring re-entrant geometry in inverse colloidal monolayers to control surface wettability

et al. 2016

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Controlling the microscopic wetting state of a liquid in contact with a structured surface is the basis for the design of liquid repellent as well as anti-fogging coatings by preventing or enabling a given liquid to infiltrate the surface structures. Similarly, a liquid can be confined to designated surface areas by locally controlling the wetting state, with applications ranging from liquid transport on a surface to creating tailored microenvironments for cell culture or chemical synthesis. The control of the wetting of a low-surfacetension liquid is substantially more difficult compared to water and requires surface structures with overhanging features, known as re-entrant geometries. Here, we use colloidal self-assembly and templating to create two-dimensional nanopore arrays with tailored re-entrant geometry. These pore arrays, termed inverse monolayers, are prepared by backfilling a sacrificial colloidal monolayer with a silica sol-gel precursor material. Varying the precursor concentration enables us to control the degree to which the colloids are embedded into the silica matrix. Upon calcination, nanopores with different opening angles result. The pore opening angle directly correlates with the re-entrant curvature of the surface nanostructures and can be used to control the macroscopic wetting behavior of a liquid sitting on the surface structures. We characterize the wetting of various liquids by static and dynamic contact angles and find correlation between the experimental results and theoretical predictions of the wetting state based on simple geometric considerations. We demonstrate the creation of omniphobic surface coatings that support Cassie-Baxter wetting states for liquids with low surface tensions, including octane (g ¼ 21.7 mN m À1). We further use photolithography to spatially confine such low-surface-tension liquids to desired areas of the substrate with high accuracy.

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Photonic Janus Films with Highly Tunable Janus Balance

Wang

Yang

Lan

et al. 2016

Adv Materials Inter

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of a tunable JB nature into Janus materials has been an easy and efficient way to offer richer functionalities to Janus systems and hence provide a better opportunity to achieve advanced functional materials. [3] So far many techniques, such as microcontact printing, O 2 plasma etching, and wetetching, have been developed to realize control over the JB value. [4] Nevertheless, current research has mainly focused on Janus particles. For Janus films, which own distinct advantages in broad areas, such as optics, sensing devices, and separation membranes, related research on the rational design and fabrication of such films is still quite rare and the further integration of the highly tunable JB nature remains a big challenge. [5] Two-dimensional (2D) colloidal crystals and their related structures are very attractive for this purpose because of their periodical morphology and corresponding iridescent appearance. [6] As a periodic structure framework, they can serve as an excellent physical mask for colloidal lithography and as a template for etching, deposition, imprinting, etc. [7] By incorporating their optical properties into diverse systems, a huge number of optical-responsive functional materials have also been achieved for an array of applications such as molecular/anion recognition and self-reporting sensors. [8] Obviously, it would be a great feat to merge a colloidal crystal structure into Janus films to endow them with excellent photonic properties and thus greatly extend their realworld applications. Up until now, only a few reports have been published on the synthesis of photonic Janus films, [9] such as Fuji et al., who exploited the selective polymerization of pyrrole at a water-exposed PS surface, [9a] and Asher et al., who demonstrated the fusion of a layer of tetraethyl orthosilicate (TEO) on top of particle arrays on water to fabricate a Janus-type 2D photonic film. [9b] Nevertheless, the JBs in these reports were fixed and not easy to modulate and the coating layers lacked any functionality, which severely restricted their usability.Here, we present a new approach for the facile synthesis of large, asymmetric, free-standing, 2D photonic Janus films with a highly tunable Janus balance and multiple functionalities based on the simple combination of nanosphere lithography at the solution interface and dopamine chemistry (Scheme 1). The key point of this strategy is the use of reactive dopamine that can selectively polymerize at the surface of water-exposed Asymmetric Janus materials are of wide-spread interest due to their unique anisotropic and directional features. In our work, through a simple combination of nanosphere lithography at the solution interface and dopamine chemistry, a new approach for the facile synthesis of large, asymmetric, freestanding, 2D photonic Janus films with a highly tunable Janus balance and multiple functionalities is developed. Herein we rationally exploit the unique properties (reducibility, self-adhesive nature, and post-modification ability) of the polydopam...

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Controlled Fabrication of Polypyrrole Surfaces with Overhang Structures by Colloidal Templating

Cited by 15 publications

References 71 publications

Three-gradient regular solution model for simple liquids wetting complex surface topologies

Three-gradient regular solution model for simple liquids wetting complex surface topologies

Tailoring re-entrant geometry in inverse colloidal monolayers to control surface wettability

Photonic Janus Films with Highly Tunable Janus Balance

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