A Highly Sensitive, Reversible, and Bidirectional Humidity Actuator by Calcium Carbonate Ionic Oligomers Incorporated Poly(Vinylidene Fluoride)

Abstract

Sensitivity and multi‐directional motivation are major two factors for developing optimized humidity‐response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi‐coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular‐scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra‐small calcium carbonate oligomers within a PVDF film endow it with an ultra‐sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity‐actuators at present, which realizes self‐motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy.

Robust and Highly Sensitive Cellulose Nanofiber-Based Humidity Actuators

“…31,32 Tang et al prepared a humidity actuator using hydrophilic calcium carbonate oligomers and hydrophobic poly (vinylidene fluoride), exhibiting a highly sensitive and reversible actuation. 33 Another interesting strategy is to tune a desirable porous structure, providing a sufficient contact area for exposing more water-absorbed sites, and introducing more nanochannels to accelerate water transport and diffusion, thus contributing to the rapid adsorption and desorption of water molecules. 34,35 Song et al reported a single-layered polyvinyl alcohol nanofibrous actuator via the electrospinning technique, which can perform ultrasensitive and complex shape deformations responding to water/moisture.…”

A Class of Rigid–Flexible Coupling Crystalline Crosslinked Polymers as Vapomechanical Actuators

“…Mechanically responsive actuators are capable of directly converting inexpensive and readily available external stimuli (e.g., chemical vapor, [1][2][3][4] light [5][6][7][8][9] ) into mechanical work, accompanied by reversible deformation of materials (e.g., expansion, contraction, bending, twisting, rolling). They have shown broad application prospects in many high-tech fields such as robots, [10,11] sensors, [12] aerospace, [13] energy storage, [14] biomedical engineering, [15] and so on.…”

A nanoconcrete welding strategy for constructing high-performance wound dressing

“…However, popular methods of modifying polymers with CaCO 3 nanoparticles still depend on weak interfacial attraction. It is worth noticing that amorphous CaCO 3 exhibits polymer-like flexibility, enabling it to copolymerize with polymers and also to encapsulate micelles, carbon nanodots, gold nanoparticles, macromolecules, small-molecule amino acids and fluoresceins during its crystallization [ [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] ]. Therefore, we here hypothesize that powerfully welding polymer chains within CaCO 3 nanocrystal through siphoning-induced occlusion, hydration-driven crystallization and dehydration-driven compression of amorphous mesoporous CaCO 3 nanoconcretes will possibly more effectively enhance the strength and toughness of the polymer.…”