Beijing University of Chemical: light responsive structured liquid

structured liquid (Structured Liquids) in recent years is based on a new class of soft biomass material particles of colloidal liquid / liquid interface and the self-assembly phase change clogging (jamming transition) constructed (e.g., a gel-continuous phase emulsion Bijels , non-spherical drops, etc.). The traditional sense of the different solid or liquid material, both characteristics of both structured liquid (the solid structural stability, flowability of the liquid), is a thermodynamically nonequilibrium systems and spans from micro to macro plurality magnitude scale. Wherein, with the use of nanoparticles and a polymer fluid / liquid interface assembly constructed synergistic surfactant nanoparticles, a simple strategy for constructing complex structured liquid. Binding force field manipulate the shape of the liquid, the liquid may be like solid material or the like by printing or molding the shape of \”processing\” to the desired, and can be generated in response to the stimulus of the external environment. However at this stage, electrostatic force (e.g. -COO- / NH3 + ion pair) is still the primary choice for building surfactant nanoparticles, structured liquid constructed more single stimulus responsive. Thus, the new construct stimuli responsive structured liquid is a research urgently direction. Recently, Beijing University of Chemical Technology Shishao Wei researcher and the University of Massachusetts at Amherst Thomas Russell academician cooperation , using α- cyclodextrin (α-CD) and azobenzene (azo) recognition of a main object in the water / oil interface orthotopic surfactant a light responsive nanoparticles. be regulated by visible and ultraviolet light can be achieved at the interface nanoparticle clogged – Solutions clogging reversible phase change, and thus imparting a respective macro-structured liquid photoresponsive (FIG. 1). This is the first interface of the host-guest chemistry and plugging system combining future diversification can be further extended to construct stimuli responsive biphasic system, the drug controlled release, liquid whole microfluidic fields exhibit a broad application prospect.

​北京化工大学:光响应型结构化液体
Figure 1. photoresponsive nanoparticle surfactant.

Researchers end groups were used azobenzene-modified polystyrene (Azo-PS)And the end groups azobenzene-modified poly-L-lactic acid (Azo-PLLA) two kinds of oil-soluble polymer ligand to the surface of the water-soluble α-CD-modified gold nanoparticles (Au-NP) assembled at the water / oil interface. The results showed that: two types of polymeric ligand may be coordinated with the Au-NP by assembling the main guest interaction, the nanoparticle forming surfactant in a water / oil interface in situ. However, based on the lower Azo-PS nanoparticles constructed interface-active surfactants, host-guest function depends only on random collisions trigger body and a guest polymer nanoparticles ligand interface. On the other hand, since Azo-PLLA between water molecules and α-CD can form hydrogen bonds, which manifests itself in a certain surfactant, Au-NP may be adsorbed to the vicinity of the interface, effectively enhance the high body and object of nanoparticles with the probability of collision between molecules thereof, and thus induce a rapid host-guest trigger action. Thus, nanoparticle-based surfactant Azo-PLLA constructed exhibits a high interfacial activity, can be quickly assembled to form a dense thin film of nanoparticles in a water / oil interface. More importantly, the introduction of the main object is effective to enhance the effect of nanoparticles binding interface can be realized in a stable nanoparticles plugging the water / oil interface of a phase change (FIG. 2).

Research ​北京化工大学:光响应型结构化液体
Figure 2. The different polymer ligands and Au-NP water / oil interface self-assembly kinetics.

Based on this, researchers constructed droplets pleated (nanoparticles at the interface is clogged state), the optical system studies the response behavior of nanoparticles surfactants and macroscopic droplets. Under visible light irradiation, trans-Azo-PLLA with α-CD occurs main guest interaction, constructed nanoparticle surfactants can be stably adsorbed to the interface, and to impart Au-NP sufficient binding energy to resist two-phase interface is generated in the reduction process the compressive stress, the droplets remained stable pleated configuration (FIG. 3a) in a long time; under UV irradiation, trans-Azo-PLLA occur cis and trans isomers, cis-Azo-PLLA formed from the blank of α-CD chamber shedding, resulting in reduced energy Au-NP interface bonding, Au-NP slack from the desorption occurs, the droplets, the surface of the folds disappearing. Interestingly, when visible light is irradiated again, the droplet surface wrinkles may occur spontaneously, and the occurrence of slight deformation, means that the master object action is triggered again, the nanoparticles tableRe surfactant formed at the interface, and clogging of a phase change (FIG. 3b). Further, by building more complex morphology structured liquid, such behavior can still be achieved in response to light (FIG. 3c).

​北京化工大学:光响应型结构化液体
Figure 3. light responsive structured liquid.

relevant papers to \”Photoresponsive Structured Liquids Enabled by Molecular Recognition at Liquid-Liquid Interfaces\” was published in the of the American Chemical Society on the Journal. Beijing University of Chemical Technology Beijing soft materials science and engineering doctoral students sophisticated Innovation Center Sun Hui Lou as the first author of the paper, Thomas Russell academician , Shishao Wei researcher as Corresponding author on the paper. The research was funded by the Beijing Natural Science Foundation and the National Natural Science Foundation of China.

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