Thermoresponsive Liquid Marbles Prepared with Low Melting Point Powder

Abstract

Thermoresponsive liquid marbles were prepared from water and 1-bromo-3-fluoro-4-iodobenzene (BFI) powder with a melting point of 46.5°C. The liquid marble can be floated on the surface of bulk water at room temperature, which is lower than the melting point of BFI. When the temperature of bulk water was increased above the melting point, the liquid marble disintegrated to leak the interior water to bulk water. Heating can be applied as a trigger of a chemical reaction between the interior reactant and another reactant in bulk water.Recently, liquid marbles that stabilize a water droplet using a hydrophobic powder at the gasliquid interface have been garnering increased attention as a new technique for handling, hauling, and preservation of liquids.1 For example, the stability of stimuli-responsive liquid marbles can be controlled by changing the powder wettability adsorbed to a water droplet. Fujii et al. 3 have reported the preparation of pH-responsive liquid marbles using polystyrene latex particles functionalized with the tertiary amino group-containing poly [2-(N,N-diethylamino)ethyl methacrylate] (pDEA, pK a = ca. 7.0) hair prepared by dispersion polymerization. The liquid marble can be floated on the surface of basic water owing to the hydrophobic deprotonated pDEA hair. Conversely, the liquid marble immediately disintegrates on exposure to acidic vapor due to protonation of the pDEA hair.We previously reported the preparation of thermoresponsive liquid marbles using poly(N-isopropylacrylamide) (pNIPAM) powder possessing a lower critical solution temperature (LCST). 4 Although pNIPAM is hydrated to dissolve molecularly in water below the LCST due to hydrogen-bonding interactions between the pendant amide groups and water molecules, it becomes hydrophobic above the LCST due to breaking of the hydrogen-bonding interactions.5 The liquid marble covered with pNIPAM powder containing a water droplet can be floated on the surface of bulk water above the LCST for more than one day. Upon cooling the bulk water below the LCST, the liquid marble disintegrated due to hydration of the pNIPAM powder. The thermoresponsive liquid marble formed from pNIPAM can be destabilized by cooling. Xu et al. 6 have reported infrared radiation (i.e. heating) responsive liquid marbles. To the best of our knowledge, thermoresponsive liquid marbles destabilized by heating above melting point have not been reported. Therefore, we have focused our attention on hydrophobic compounds with low melting points as hydrophobic powders to prepare thermoresponsive liquid marbles. If a hydrophobic powder with a low melting point is used to prepare a liquid marble, the liquid marble should be destabilized by heating above the melting point. The advantage of such thermoresponsive liquid marbles can be the control of the disintegration temperature by the melting point of the hydrophobic powder.In this report, we studied thermoresponsive liquid marbles prepared from water and hydrophobic 1-bromo-3-fluoro-4-iodobenzene (BFI, 97+%, Wako Pure Chemical) pow...

The Potential of Liquid Marbles for Biomedical Applications: A Critical Review

“…With these contaminants, the water surface tension decreased and the floating LM lost their integrity, revealing the water contamination without water sampling. On the same topic of responsive floating LM to external stimuli, Nakai et al reported a thermoresponsive LM that lost their integrity when the temperature increased and reached 46.5 °C . This temperature corresponded to the melting point of the material used in the LM coating.…”

Stimuli‐Responsive Liquid Marbles: Controlling Structure, Shape, Stability, and Motion

“…A liquid marble stabilized with BFI powder can float on bulk water. With increasing temperature of the bulk water, the liquid marble is disrupted at approximately 50 °C, which is close to the melting point . The BFI powder is adsorbed to the water droplet surface, and there is an air gap between the water in the liquid marble and the bulk water phase below the melting point.…”

Elemental Sulfur-Stabilized Liquid Marbles: Properties and Applications

“…14,18 Some liquid marbles can respond to various stimuli such as mechanical stress, 19 pH, 20 and temperature. 21,22 Deformed liquid marbles can be prepared by withdrawing the water content of the liquid marbles using a pipette. 23 It should be taken into consideration that the jamming effect enables the liquid marbles to deform to nonspherical shapes 24−26 as the monolayer of the hydrophobic sol−gel film mechanically transferred to the water droplet surface caused the jamming effect and unusual shapes of liquid marbles.…”

“…To obtain nonspherical shapes of liquid marbles, acoustic levitation, electrical flow or magnetic field , were used, which enable temporary deformations of the liquid marbles’ shape, but it is self-reversed to the original spherical shape when the force is removed . Such strategies are used to manipulate the liquid marbles, for instance, electric or magnetic fields require adequate stimuli-responsive systems. , Some liquid marbles can respond to various stimuli such as mechanical stress, pH, and temperature. , Deformed liquid marbles can be prepared by withdrawing the water content of the liquid marbles using a pipette . It should be taken into consideration that the jamming effect enables the liquid marbles to deform to nonspherical shapes − as the monolayer of the hydrophobic sol–gel film mechanically transferred to the water droplet surface caused the jamming effect and unusual shapes of liquid marbles. , Cylindrical shape oil marbles fabricated using modified fluorinated solid particles with omniphobic properties have been reported.…”