Deep-Eutectic Solvents as MWCNT Delivery Vehicles in the Synthesis of Functional Poly(HIPE) Nanocomposites for Applications as Selective Sorbents

Abstract

We report an alternative green strategy based on deep-eutectic solvents (DES) to deliver multiwalled carbon nanotubes (MWCNTs) for a bottom-up approach that allows for the selective interfacial functionalization of nonaqueous poly(high internal phase emulsions), poly(HIPEs). The formation and polymerization of methacrylic and styrenic HIPEs were possible through stabilization with nitrogen doped carbon nanotube (CN) and surfactant mixtures using a urea-choline chloride DES as a delivering phase. Subtle changes in CN concentration (less than 0.2 wt % to the internal phase) produced important changes in the macroporous monolith functionalization, which in turn led to increased monolith hydrophobicity and pore openness. These materials displayed great oleophilicity with water contact angles as high as 140° making them apt for biodiesel, diesel, and gasoline fuel sorption applications. Overall, styrene divinylbenzene (StDvB) based poly(HIPEs) showed hydrophobicity and fuel sorption capacities as high as 4.8 (g/g). Pore hierarchy, namely pore openness, regulated sorption capacity, and sorption times where greater openness resulted in faster sorption and increased sorption capacity. Monoliths were subject to 20 sorption-desorption cycles demonstrating recyclability and stable sorption capacity. Finally, CN/surfactant hybrids made it possible to reduce surfactant requirements for successful HIPE formation and stabilization during polymerization. All poly(HIPEs) retained acceptable conversion as a function of CN loading nearing 90% or better with thermal stability as high as 283 °C.

Nonaqueous Synthesis of Macroporous Nanocomposites Using High Internal Phase Emulsion Stabilized by Nanohydroxyapatite

“…09‐432) . A close examination of pure NHA standard in comparison to the DES recovered NHA, reveals no changes or shifts in the previously described diffraction pattern values, which is indicative that its crystalline structural integrity is maintained throughout the dispersion in the continuous phase in contact with DES and polymerization process, similarly to HA synthesized in DES and carbon nanotubes . On the other hand, the pMMA poly(HIPE) shows a distinct amorphous peak at 19.3° angle 2θ and two distinct minor peaks at 23.0 and 81.7° angle 2θ, respectively.…”

“…These results suggest that the inclusion of nanomaterials like NHA may impact the surface roughness therefore making the material more hydrophobic,[15b,24] despite the HA hydrophilic character reported . This observation points out that the modification of surface wettability is a consequence of the homogenous integration of NHA functionalizing the poly(HIPE) inner walls as it was the case for a similar approach applied to carbon nanotubes …”

“…Recently reported, the strategy of bringing together surfactant and particle HIPE stabilization has created a new opportunity to integrate Pickering HIPEs' stability and functionality to traditional surfactant HIPEs' pore tunability . Such control becomes crucial to design functional scaffolds that suit specific requirements for bone tissue replacements, for example, having bioactive inorganic components like hydroxyapatite (HA).…”

“…Developing HIPEs in DESs offers not only a more benign route in terms of the use of toxic solvents and additional components, but also poly(HIPEs) processing (e.g., extracting the internal phase)[16a] prior contacting with living systems becomes easier by using DESs. A more interesting approach is the opportunity to explore experimental conditions at which traditional aqueous HIPEs are barely stable,[7,16b,d] thus broadening the palette of morphologies available through HIPE polymerization.…”

Influence of Hydration on the Structure and Interactions of Ethaline Deep‐Eutectic Solvent: A Spectroscopic and Computational Study

“…Such attentions are raised from their improved properties . They are potential candidates for a broad range of applications in separation, electrochemistry, nanoscience, and biochemistry …”