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

Abstract

Microgels, 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 bonding. 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 transition. Therefore, the PVA–GO composite remains undissolved when it is directly exposed to water by oil‐shell rupture. These composite microgels can be also produced using poly(ethylene oxide) or poly(acrylic acid), instead of PVA. In addition, the microgels can be functionalized by incorporating other polymers in the presence of the hydrogel‐forming polymers. It is shown that the multicomponent microgels made from a mixture of polyacrylamide, PVA, and GO show an excellent adsorption capacity for impurities.

Facile Strategy to Construct High-Performance Nanofiltration Membranes by Synergy of Graphene Oxide and Polyvinyl Alcohol

“…More GO remained in the selective layer because of the hydrogen bonding between PVA and GO. 42,43 As a result, the TFN-PG-100 membrane shows a more pronounced −OH absorption peaks at 3440 cm −1 compared with the TFN-GO-100 membrane. 44 XPS method with a higher detective sensitivity was further conducted to analyze the chemical composition of the fabricated composite NF membrane.…”

“…Moreover, the steric hindrance toward PIP diffusion was strengthened by the hydrogen-bonding network of PVA and GO. 42,43 To further clarify the synergetic effects of PVA and GO, the TFN-GO series membranes with the introduction of only the GO additive into the aqueous solutions were fabricated and characterized. As shown in Figure 5, the addition of GO also led to the formation of highly wrinkled surfaces, probably due to the reduced diffusion rate of PIP monomers caused by the steric hindrance of GO and the strong hydrogen bonding between GO and PIP.…”

A multi-interface CoNi-SP/C heterostructure for quasi-solid-state hybrid supercapacitors with a graphene oxide-containing hydrogel electrolyte

“…4a, PVA was first dissolved in a GO dispersion under stirring at 90 °C, and they cross-link with each other through the hydroxyl groups in PVA chains with oxygen-containing functional groups (such as hydroxyl groups, carboxyl groups, and epoxy groups) of GO. 59,60 Then, PVA/PAM was obtained through the hydrogen-bonding interactions between the hydroxyl group of PVA chains and the amide group of the acrylamide (AM) monomer and simultaneous free radical polymerization of AM using the crosslinking agent under ultraviolet irradiation. 61,62 Fourier transform infrared spectroscopy (FTIR) was conducted to verify the generation of the PVA/PAM/GO hydrogel.…”

Microfluidic production of monodisperse emulsions for cosmetics

“…If an emulsion with the same droplet size is uniformly dispersed in another liquid phase and has a sufficient size for direct observation, its applicability is very high in the cosmetic industry. Due to these advantages, many studies have been conducted for designing uniform sized emulsion drops based on a microfluidic technology, employing various surface-active substances such as low molecular surfactants, 8-10 polymeric surfactants, [11][12][13] and colloidal particles. [14][15][16][17] For visual enjoyment that comes from the appearance of emulsion products, several cosmetic companies have attempted to generate monodisperse emulsions while varying their size, shape, and texture.…”