Surface Optics and Color Effects of Liquid Metal Materials

Abstract

Liquid metals (LMs) are emerging as new functional materials with rather unique physical or chemical behaviors. They are generally safe and nontoxic, have high boiling points, reflectivities, good thermal and electrical conductivities, flexibility, fluidity, self‐healing capability and remain in liquid state at room temperature. However, the further applications of LMs are limited by their single‐color physical appearance, such as working in the situations with imposed stringent requirements for color and aesthetics. Recently, the color and fluorescence functionalization of LMs have overcome many conventional technical bottlenecks and opened significant potential for emerging applications in numerous fields owing to their rich colors and unique liquid structure. In this review, the recent developments in the optical properties, color and fluorescence effects of LMs are comprehensively investigated. The synthesis, structures, properties, chromogenic mechanisms, and potential photoelectric applications of colorful LMs are systematically analyzed and compared. The effectiveness and characteristics of colorful LMs induced by coating, mixing, compounding, surface modification, external stimuli are provided, aiming to establish a potential system for the synthesis and practices of colorful LMs. Finally, the challenges and prospects in the field have also been identified and explained to preferably guide further scientific and technical research in the coming time.

Liquid metal droplet dynamics

“…Once needed, the fluorescent particles could be easily separated from the LM droplets under the action of an electric field. Such colorful LM droplets can open tremendous application opportunities in the field of photoelectric information where a requirement for color and esthetics is imposed 55,56 …”

“…Such colorful LM droplets can open tremendous application opportunities in the field of photoelectric information where a requirement for color and esthetics is imposed. 55,56 In contrast to simply relying on the wettability of LM surface oxides to coating particles in air, Tang et al 57 prepared LM-copper (Cu) composite droplets based on redox reactions in solution environment.…”

Liquid-Metal Molecular Scissors

“…6 However, as mentioned elsewhere, current molecular editing and assembly techniques are typically heavily reliant on cumbersome processes, complex reagents, and harsh reaction conditions, which are major obstacles to the advancement of this technology. 7 Among the many exciting functional materials, liquid metals are emerging as new-generation materials with unique physical and chemical behavior. 8 Liquid metals are safe and nontoxic, have high boiling points and reflectivities, good thermal and electrical conductivities, high flexibility, fluidity, self-healing capabilities, and remain in a liquid state at room temperature.…”

“…Molecular cutting, editing, and recombination are the effective strategies for constructing emerging functional substances and providing infinite possibilities for cutting-edge science advancements, based on directional chemical clipping, in fields such as biopolymers, small molecular substances, life sciences, advanced materials, biomedicine, and energy and environment research. , Historically, the ability to control and manipulate matters at the molecular level has led to scientific advancement and significant improvements in the quality of human life . However, as mentioned elsewhere, current molecular editing and assembly techniques are typically heavily reliant on cumbersome processes, complex reagents, and harsh reaction conditions, which are major obstacles to the advancement of this technology …”

Gallium-based liquid metals as reaction media for nanomaterials synthesis

“…12,13 More interestingly, LMs spontaneously form an ultra-thin oxide layer when exposed to air. 14,15 This oxide skin, with weak adhesion to the nonpolar surface of the flowing metallic matrix, is easily transferable to any desired substrate. 16,17 However, upon the removal of the oxide skin, LMs can provide atomically smooth interfaces, making them suitable as soft and ultra-smooth templates for low temperature deposition and 2D material growth.…”