Photo/Thermo Dual Stimulus-Responsive Liquid Marbles Stabilized with Polypyrrole-Coated Stearic Acid Particles

Abstract

In this study, we report on the fabrication of photo/thermo dual stimulus-responsive liquid marbles (LMs) that can be disrupted by light irradiation and/or heating. To stabilize the LMs, we synthesized micrometer-sized stearic acid (SA) particles coated with overlayers of polypyrrole (PPy) by aqueous chemical oxidative seeded dispersion polymerization. The SA/PPy core–shell particles could adsorb at the air–water interface to stabilize LMs by rolling water droplets on the particle powder bed. The presence of SA, known as a phase-change material, which undergoes a transition from solid to liquid by heating, and PPy, which can transduce light to heat, gives rise to the photo and thermo dual stimulus-responsive characters of the LMs. The disruption of the LMs could be induced in a cascade manner: light irradiation on the LM induced a temperature increase, followed by melting of the SA component on the LM surface, leading to its disruption and release of the inner water. The disruption time is linked to the PPy loading and light irradiation power, and it can be tuned from quasi-instantaneous to a few tens of seconds. The melting of SA due to a light-induced phase change from the solid to liquid state is a new mechanism to trigger the disruption of LMs. We finally demonstrated two applications of the LMs as a light-responsive microreactor and a sensor.

pH-triggered adjustable bursting of liquid marbles in water pools

“…E-mail: umanna@iitg.ac.in b Centre for Nanotechnology, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India specic stimuli, and such earlier reported approaches remained inapplicable to adjust the lifetime of LMs in the presence of respective stimuli, as shown in Table 1. 4,5,7,8,14,15,23,24,26,[32][33][34][35][36][37][38][39][40] Thus, the report of mechanically robust LMs, having the ability to (a) automatically release the inner liquid at a precise and pre-dened time without having any external intervention, and (b) adjustable triggered bursting of the inner liquid on the water pool in both acidic and alkaline conditions, is yet to be introduced in the literature. Such principally distinct design would likely provide an elegant avenue for deriving functional so materials for different fundamental and applied studiesincluding adjustable triggered drug release, on-demand chemical reaction and rapid chemical sensing.…”

pH-Responsive Liquid Marbles Stabilized with Chitosan-Stearic Acid-Conjugated Particles

“…Due to the ease of chemical modifications with the amino groups in CS, various derivatives have been synthesized − for a range of applications, such as bioreactors, photonic materials, photocatalysts, flocculants, antimicrobials, − emulsifiers, nematode control, food packing, and drug delivery carriers . SA is a natural fatty acid widely used as a biocompatible and biodegradable hydrophobizer for solid substrates. − Due to its versatility, abundance, and low cost, SA is a particularly attractive material among fatty acids . In this study, we first synthesized CS-SA-conjugated particles by direct solvent-free thermal amidation between CS and SA.…”

Photo- and Thermoresponsive Liquid Marbles Based on Fatty Acid as Phase Change Material Coated by Polypyrrole: From Design to Applications

“…Recently, we succeeded in realization of LMs, which can disrupt by application of light and temperature dual stimuli, using the core–shell particles based on stearic acid (SA) core covered with a polypyrrole (PPy) overlayer (SA/PPy particles) as an LM stabilizer . SA has an alkyl chain with 18 carbons and a corresponding melting point at 69 °C and has been used widely as a PCM. ,− PPy is one of the conjugated polymers, which can efficiently transduce near-infrared (NIR) light into heat, , enabling melting of SA core by NIR light irradiation.…”