Shape‐Designable Polyhedral Liquid Marbles/Plasticines Stabilized with Polymer Plates

Abstract

Polyhedral liquid marbles/plasticines are prepared using (sub)millimeter‐sized polymer plates as a stabilizer and water as an inner liquid. Precise control of size and shape can be successfully performed by tuning the size ratio of the water droplet and the plate, number of plates adsorbed to the droplet, coalescence (jointing) of multiple polyhedral liquid marbles/plasticines, and application of external mechanical stress. Thanks to interfacial jamming of the plates, plastic deformation of the liquid marbles/plasticines is achieved. The authors are able to fabricate liquid marbles/plasticines with various shapes including A–Z letters of alphabet. Liquid marble/plasticine with an aspect ratio exceeding 800, the largest aspect ratio ever reported, is also successfully prepared; the length of the liquid marble/plasticine exceeded 1.5 m. The liquid marbles can be picked up and be piled up on top of each other using tweezers or fingers. Furthermore, Janus‐type liquid marbles/plasticines with different curvatures and different stabilizers in a single liquid marble/plasticine can be fabricated by coalescence (jointing) of near‐spherical and cuboid liquid marbles/plasticines stabilized by plates with different sizes. An internal liquid flow from the near‐spherical liquid marble to the cuboid liquid marble/plasticine immediately after jointing is observed, making this system act as a micropump.

Formation of liquid marbles & aggregates: rolling and electrostatic formation using conductive hexagonal plates

“…33 The platelet particles herein would retain this characteristic whilst exploiting the unique geometry of the polyhedral liquid marbles as potential actuators and liquid delivery vessels. 21,34 These newly synthesised coatings will be investigated with respect to their viability as liquid marble stabilisers using both the traditional rolling 1,4,21 and the contactless electrostatic method of liquid marble formation, during which their electrostatic transfer behaviour will be investigated. 22,23,25,28,35…”

Boxes fabricated from plate-stabilized liquid marbles

“…These observations revealed that the plates were adsorbed as monolayers on the LMs (50 µL) (Supporting Information and Figure S3). The air-water-plate contact lines were mainly pinned at the inner edge of the plates and one large face of the plate contacted with water phase, as preciously observed 35,36 . The contact lines sometimes crossed to the side wall of the plates.…”

“…Shape-designability is one of advantages of the LMs stabilized with plates 35,36 . It is worth noting that "I"-shaped LM could be fabricated by merging multiple LMs (Figure S8).…”

“…Until now, (near)spherical particles and their flocs have been generally used as a stabilizer and studies on LMs stabilized with well-defined nonspherical stabilizers monodispersed in shape and size have been limited. Recently, hydrophobic, monodispersed millimeter-sized polymer platelets were used as an LM stabilizer to stabilize polyhedral LMs [35][36][37] . Taking the various applications of the LMs into consideration, investigation of the relationship between shape of stabilizer and formability, stability and structure of LMs is crucial.…”

Controllable Positive/Negative Phototaxis of Millimeter-Sized Objects with Sensing Function

“…Liquid droplets coated by solid particles self-assembled at the gas–liquid interface are called liquid marbles (LMs). − Various kinds of functional solid particles have been utilized as an LM stabilizer. , Recently, highly transparent LMs were successfully fabricated using millimeter-sized polymer plates. , The LMs had polyhedral shapes, and an inner liquid phase could be easily observed with the naked eye, thanks to the low light-scattering property of the plates, making them suitable as a microreactor/sensor. The LMs can move easily on the water surface and can conveniently transport inner encapsulated materials and solid particles/grains adsorbed to the LM surfaces.…”