Programmable co-assembly of oppositely charged microgels

Abstract

Here we report the development of an aqueous, self-assembling system of oppositely charged colloids leading towards particle arrangements with controlled order. The colloidal system consists of two types of particles, each consisting of refractive index matched colloidal core-shell microgel particles, which are either negatively charged or amphoteric. By slowly decreasing the pH of our system below the isoelectric point of the amphoteric particles, changing their net charge from negative to positive, the co-assembly of the colloids is induced. By using different buffer concentrations, we gain temporal and kinetic control over the acidification process and thus the ability to program the co-assembly of the two particles species.

Precise Macroscopic Supramolecular Assembly by Combining Spontaneous Locomotion Driven by the Marangoni Effect and Molecular Recognition

“…[3,4] Afterwards,m any groups demonstrated macroscopic assembly of hydrogel building blocks through supramolecular interactions. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] To promote research on macroscopic supramolecular assemblies from the hydrogel systems to rigid building blocks,w eh ave proposed ageneral principle of aflexible spacing coating to realize selfassembly of macroscopic polydimethylsiloxane (PDMS) or polymethyl methacrylate building blocks. [19] However,a ll of the aforementioned work involved an external energy source such as shaking or rotating to drive the building blocks larger than 10 mmthat could hardly diffuse or collide with each other by molecular thermal motion.…”

Photo-triggered microgel aggregation using o -nitrobenzaldehyde as aggregating power source

“…In contrast, the aggregation behavior of the cationic and anionic microgels was observed in neither acidic nor basic condition (pH = 2 and 12, respectively). It was considered that they did not aggregate at pH 2 or 12 because the zeta potential of cationic or anionic microgel was neutralized and ionic interaction between cationic and anionic microgel was weakened …”

“…It was reported that some microgels aggregate voluntarily in solvents . For example, cationic and anionic microgels form aggregates due to the electrostatic interaction in water . Similarly to biomolecules, microgel aggregation has unique properties general gel materials do not have.…”

Photonic Paints: Structural Pigments Combined with Water‐Based Polymeric Film‐Formers for Structurally Colored Coatings

“…The colloidal templates, poly(methyl methacrylate) (PMMA) or poly(styrene) (PSt) with 10 wt% poly( N ‐isopropyl acrylamide)(PNIPAm), are made via a highly scalable emulsion polymerization, with NIPAm forming polymeric emulsifiers in situ . The resulting surface chemistry, with PNIPAm hairs terminated in negatively charged sulfate groups from the initiator, provides electrosteric stabilization, allowing the colloids to be dispersed in water with the silica sol and preventing aggregation during colloidal assembly.…”