Macroscopic Supramolecular Assembly through Electrostatic Interactions Based on a Flexible Spacing Coating

Abstract

Macroscopic supramolecular assembly (MSA) is a recent advance in supramolecular chemistry that involves associating large building blocks with a size larger than 10 µm through noncovalent interactions. However, until now the applicable material system is rather limited to hydrogels, and MSA of rigid materials with supramolecular interactions widely used in molecular assembly has rarely been reported due to the difficulty in achieving multivalency between rigid surfaces. Herein, the concept of flexible spacing coating is applied with highly flowable properties, and the electrostatic-interaction-driven MSA of relatively rigid polydimethylsiloxane building blocks is demonstrated. With the flexible spacing coating of a polyelectrolyte multilayer, the oppositely charged rigid building blocks can realize MSA under shaking in water for 5 min. The major contribution of the electrostatic interaction is confirmed by both qualitative controlled MSA experiments in other solvents, disassembly in ionic solution and quantitative results with an in situ force measurement method.

Parallel and Precise Macroscopic Supramolecular Assembly through Prolonged Marangoni Motion

“…Unlike molecular assembly, in which recognition and binding is reversible and can often obtain kinetic energy from the thermal motion of the components, the realization of MSA faces two major challenges: 1) The large surfaces through which supramolecular motifs interact are usually very rough on the molecular scale, which is unfavorable for realizing efficient interfacial supramolecular interactions; and (2) a driving force is required to achieve collision between and assembly of the macroscopic building blocks, as they are too large to be propelled. Until now, the first issue has been addressed by introducing a flexible spacing coating to mediate the surface roughness, while the second challenge is overcome with external agitation, such as rotation or shaking of the medium in which the macroscopic building blocks assemble, or magnetically assisted motion to cause directed diffusion and collision of the building blocks . As a result, 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, leading to facially offset, nonequilibrium assemblies, which are undesired .…”

“…The interactive system is introduced through layer‐by‐layer assembly of oppositely charged polyelectrolytes onto thin PDMS sheets. This multilayer polyelectrolyte coating is produced by sequential deposition of a flexible spacing coating of poly(ethyleneimine)/poly(acrylic acid) (PAA), an antiadhesion layer of poly‐(diallyldimethylammonium chloride) (PDDA)/poly(sodium‐ p ‐styrenesulfonate) (PSS), and an electrostatic interactive coating of PDDA/PAA with either PDDA or PAA as the outermost layer to give either a positively or negatively charged surface, as desired . The hydrogel cubes and the coated PDMS sheets are assembled with the abovementioned low‐density substrate of expanded polystyrene (EPS, density=0.011–0.032 g cm −3 , dimensions=8×8×5 mm 3 ) that was pretreated with a commercial fluorinated silane solution to induce superhydrophobicity for reduction of fluidic drag.…”

“…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. 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. 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.…”

“…Thes elfpropulsion system is fabricated by admixing the surfactant sodium dodecyl sulfonate (SDS) as af uel into ap olyacrylamide hydrogel cube (2 2 2mm 3 )f abricated from at emplated method. [14] Theh ydrogel cubes and the coated PDMS sheets are assembled with the abovementioned low-density substrate of expanded polystyrene (EPS,d ensity = 0.011-0.032 gcm À3 , dimensions = 8 8 5mm 3 )t hat was pretreated with ac ommercial fluorinated silane solution to induce superhydrophobicity for reduction of fluidic drag.T wo positively or negatively charged PDMS sheets are attached to the EPS host in the orthogonal direction (see Scheme 1), and two SDS hydrogels are embedded in the other two side surfaces through two precut cavities with dimensions of 2 2 2mm 3 . [14] Theh ydrogel cubes and the coated PDMS sheets are assembled with the abovementioned low-density substrate of expanded polystyrene (EPS,d ensity = 0.011-0.032 gcm À3 , dimensions = 8 8 5mm 3 )t hat was pretreated with ac ommercial fluorinated silane solution to induce superhydrophobicity for reduction of fluidic drag.T wo positively or negatively charged PDMS sheets are attached to the EPS host in the orthogonal direction (see Scheme 1), and two SDS hydrogels are embedded in the other two side surfaces through two precut cavities with dimensions of 2 2 2mm 3 .…”

Parallel and Precise Macroscopic Supramolecular Assembly through Prolonged Marangoni Motion

“…Thei nteractive system is introduced through layer-by-layer assembly of oppositely charged polyelectrolytes onto thin PDMS sheets.T his multilayer polyelectrolyte coating is produced by sequential deposition of af lexible spacing coating of poly(ethyleneimine)/poly(acrylica cid) (PAA), an antiadhesion layer of poly-(diallyldimethylammonium chloride) (PDDA)/poly(sodium-p-styrenesulfonate) (PSS), [12] and an electrostatic interactive coating of PDDA/ PA Awith either PDDAorP AA as the outermost layer to give either apositively or negatively charged surface,asdesired. [14] Theh ydrogel cubes and the coated PDMS sheets are assembled with the abovementioned low-density substrate of expanded polystyrene (EPS,d ensity = 0.011-0.032 gcm À3 , dimensions = 8 8 5mm 3 )t hat was pretreated with ac ommercial fluorinated silane solution to induce superhydrophobicity for reduction of fluidic drag.T wo positively or negatively charged PDMS sheets are attached to the EPS host in the orthogonal direction (see Scheme 1), and two SDS hydrogels are embedded in the other two side surfaces through two precut cavities with dimensions of 2 2 2mm 3 .…”