Macroscopic supramolecular assembly (MSA) is a rising concept in supramolecular science, in which building blocks with sizes exceeding 10 μm self-assemble into larger structures. MSA faces the challenge of developing appropriate self-propulsion strategies to improve the motility of the macroscopic building blocks. Although the Marangoni effect is an ideal driving force with random motion paths, excessive aggregation of the surfactant and fast decay of motion remain challenging problems. Hence, a molecular interference strategy to drive the self-assembly over longer times by finely controlling the interfacial adsorption of surfactants using dynamic equilibria is proposed. Surfactant depletion through molecular recognition in the solution to oppose fast interfacial aggregation efficiently facilitates macroscopic motion and assembly. The resulting motility lifetime is extended remarkably from 120 s to 2200 s; with the improved kinetic energy, the assembly probability increases from 20 % to 100 %.
Supramolecular self-assembly of μm-to-mm sized components is essential to construct complex supramolecular systems. However, the selective assembly to form designated structures at this length scale is challenging because the short-ranged molecular recognition could hardly direct the assembly of macroscopic components. Here we demonstrate a self-sorting mechanism to automatically identify the surface chemistry of μm-to-mm components (A: polycations; B: polyanions) based on the A-B attraction and the A-A repulsion, which is realized by the additivity and the competence between long-ranged magnetic/capillary forces, respectively. Mechanistic studies of the correlation between the magnetic/capillary forces and the interactive distance have revealed the energy landscape of each assembly pattern to support the self-sorting results. By applying this mechanism, the assembly yield of ABA trimers has been increased from 30%~40% under conventional conditions to 100% with self-sorting. Moreover, we have demonstrated rapid and spontaneous self-assembly of advanced chain-like structures with alternate surface chemistry.
Macroscopic supramolecular assembly (MSA) is ar ising concept in supramolecular science,i nw hichb uilding blocks with sizes exceeding 10 mms elf-assemble into larger structures.MSA faces the challenge of developing appropriate self-propulsion strategies to improve the motility of the macroscopic building blocks.A lthough the Marangoni effect is an ideal driving force with random motion paths,e xcessive aggregation of the surfactant and fast decayo fm otion remain challenging problems.Hence,amolecular interference strategy to drive the self-assembly over longer times by finely controlling the interfacial adsorption of surfactants using dynamic equilibria is proposed. Surfactant depletion through molecular recognition in the solution to oppose fast interfacial aggregation efficiently facilitates macroscopic motion and assembly.T he resulting motility lifetime is extended remarkably from 120 sto2200 s; with the improved kinetic energy,the assembly probability increases from 20 %t o100 %.Macroscopic supramolecular assembly (MSA), in which non-covalently interactive motifs facilitate the assembly of building blocks of sizes exceeding 10 mm, [1][2][3] presents atopical challenge in supramolecular chemistry and colloid science. MSA is meaningful for the scalable manufacture of structured materials through self-assembly, [4][5][6] the fabrication of tissue scaffolds, [7,8] and the study and interpretation of adhesion phenomena. [9][10][11] Unlike molecular assembly,i nw hich recognition and binding is reversible and can often obtain kinetic energy from the thermal motion of the components,t he realization of MSA faces two major challenges:1 )The large surfaces through which supramolecular motifs interact are usually very rough on the molecular scale,w hich is unfavorable for realizing efficient interfacial supramolecular interactions;and (2) adriving force is required to achieve collision between and assembly of the macroscopic building blocks,as they are too large to be propelled. Until now,t he first issue has been addressed by introducing af lexible spacing coating to mediate the surface roughness, [12][13][14] while the second challenge is overcome with external agitation, such as rotation or shaking of the medium in which the macroscopic building blocks assemble,o rm agnetically assisted motion to cause directed diffusion and collision of the building blocks. [1][2][3][4] As ar esult, the quality of the desired precise alignment of building blocks is poor compared with that of the alignment achieved by molecular self-assemblies because the macroscopic assembly geometries are largely determined by complex dynamics during the agitation or shaking process, [6] leading to facially offset, nonequilibrium assemblies,w hich are undesired. [15] Therefore,t oimprove the motility of the macroscopic building blocks and reduce the uncontrolled dynamics of external agitation techniques,a ppropriate selfpropulsion strategies for achieving MSA are urgently required.Thef ield of active self-propulsion has yielded various strategie...
The photothermal Marangoni effect enables direct light-to-work conversion, which is significant for realizing the self-propulsion of objects in a noncontact, controllable, and continuous manner. Many promising applications have been demonstrated in micro- and nanomachines, light-driven actuators, cargo transport, and gear transmission. Currently, the related studies about photothermal Marangoni effect-induced self-propulsion, especially rotational motions, remain focused on developing the novel photothermal materials, the structural designs, and the controllable self-propulsion modes. However, extending the related research from the laboratory practice to practical application remains a challenge. Herein, we combined the photothermal Marangoni effect-induced self-propulsion with the triboelectric nanogenerator technology for sunlight intensity determination. Photothermal black silicon, superhydrophobic copper foam with drag-reducing property, and triboelectric polytetrafluoroethylene film were integrated to fabricate a triboelectric nanogenerator. The photothermal-Marangoni-driven triboelectric nanogenerator (PMD-TENG) utilizes the photothermal Marangoni effect-induced self-propulsion to realize the relative motion between the triboelectric layer and the electrode, converting light into electrical signals, with a peak value of 2.35 V. The period of the output electrical signal has an excellent linear relationship with the light intensity. The accessible electrical signal generation strategy proposed here provides a new application for the photothermal Marangoni effect, which could further inspire the practical applications of the self-powered system based on the photothermal Marangoni effect, such as intelligent farming.
Self‐assembly of μm‐to‐mm components is important for achieving all‐scale ordering with requirements of extra energy for motion and interaction of components. Marangoni flows caused by surfactants on water provide appropriate energy but have limited lifetimes because of the inevitable interfacial aggregation and difficult decomposition of aggregated covalent surfactants that inactivate Marangoni effects. Here we have synthesized a supra‐amphiphile Marangoni “fuel”—sodium‐4‐(benzylideneamino) benzenesulfonate (SBBS)—that can be hydrolyzed in a timely manner to a species without surface activity to extend the motion time by 10‐fold. The motion was optimized at pH=2 by a fine equilibrium between the releasing and removal of interfacial SBBS, leading to the self‐assembly of millimeter‐scaled ordered dimers. The underlying mechanism was interpreted by motion analyses and simulation. This strategy provides an active solution to self‐assembly at the μm‐to‐mm scale, as well as interactive ideas between miniaturized chemical robots.
Self‐assembly of μm‐to‐mm components is important for achieving all‐scale ordering with requirements of extra energy for motion and interaction of components. Marangoni flows caused by surfactants on water provide appropriate energy but have limited lifetimes because of the inevitable interfacial aggregation and difficult decomposition of aggregated covalent surfactants that inactivate Marangoni effects. Here we have synthesized a supra‐amphiphile Marangoni “fuel”—sodium‐4‐(benzylideneamino) benzenesulfonate (SBBS)—that can be hydrolyzed in a timely manner to a species without surface activity to extend the motion time by 10‐fold. The motion was optimized at pH=2 by a fine equilibrium between the releasing and removal of interfacial SBBS, leading to the self‐assembly of millimeter‐scaled ordered dimers. The underlying mechanism was interpreted by motion analyses and simulation. This strategy provides an active solution to self‐assembly at the μm‐to‐mm scale, as well as interactive ideas between miniaturized chemical robots.
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