Composite Microgels Created by Complexation between Polyvinyl Alcohol and Graphene Oxide in Compressed Double ‐Emulsion Drops

Composite microgels are formed by complexation between polyvinyl alcohol (PVA) and graphene oxide (GO) in shrinking double ‐emulsion drops. By setting enrichment faster than diffusion, PVA‐tethered GO sheets are rapidly concentrated along droplet interfaces, leading to gelation through hydrogen bonding without any chemical cues. This microfluidic approach is highly biocompatible and applicable for various polymers, potentially serving as a useful means to produce microgels. AbstractMicrogels, microparticles made of hydrogels, show fast diffusion kinetics and high reconfigurability while maintaining the advantages of hydrogels, being useful for various applications. Here, presented is a new microfluidic strategy for producing polymer ‐graphene oxide (GO) composite microgels without chemical cues or a temperature swing for gelation. As a main component of microgels, polymers that are able to form hydrogen bonds, such as polyvinyl alcohol (PVA), are used. In the mixture of PVA and GO, GO is tethered by PVA through hydrogen bondi ng. When the mixture is rapidly concentrated in the core of double‐emulsion drops by osmotic‐pressure‐driven water pumping, PVA‐tethered GO sheets form a nematic phase with a planar alignment. In addition, the GO sheets are linked by additional hydrogen bonds, leading to a sol–gel transiti on. Therefore, the PVA–GO composite remains undissolved when it is directly exposed to water by oil‐shell rupture. These composite microgels can be...
Source: Small - Category: Nanotechnology Authors: Tags: Full Paper Source Type: research