Aqueous Nonionic Copolymer-Functionalized Laponite Clay. A Thermodynamic and Spectrophotometric Study To Characterize Its Behavior toward an Organic Material

Abstract

The affinity of functionalized Laponite clay toward an organic material in the aqueous phase was explored. Functionalization was performed by using triblock copolymers based on ethylene oxide (EO) and propylene oxide (PO) units that are EO(11)PO(16)EO(11) (L35) and PO(8)EO(23)PO(8) (10R5). Phenol (PhOH) was chosen as organic compound, which represents a contaminant prototype. To this purpose, densities and enthalpies of mixing as well as PhOH UV-absorption spectra were determined. The enthalpy and the spectrophotometry revealed PhOH-Laponite interactions whereas the volume did not. It emerged that the area occupied by PhOH on the Laponite surface is equal to that computed from the partial molar volume of PhOH in water, corroborating the insensitivity of the experimental volumes to the adsorption process. The situation where both PhOH and copolymer are simultaneously present in the aqueous Laponite suspension was also investigated. It turned out that the copolymer replaces PhOH from the water/Laponite clay interface, resulting in L35 being the more efficient. Moreover, the lateral copolymer-phenol interactions enhance the anchoring of PhOH to the solid surface. The reverse copolymer exercises the most important relevant effect. The UV-absorption spectra of PhOH in the water + copolymer + Laponite mixtures provided information that is consistent with those given by the calorimetric experiments. In conclusion, the aqueous copolymer-functionalized Laponite presents surface properties very different from the bare Laponite, favoring the removal of the organic compound from the solid surface.

Insight into the Broad Field of Polymer Nanocomposites: From Carbon Nanotubes to Clay Nanoplatelets, via Metal Nanoparticles

“…The X-ray diffraction data of the nanocomposites indicated an exfoliated structure. Finally, De Lisi et al also investigated the affinity toward an organic material, phenol, of the modified Laponite ® with PEO-PPO-PEO triblock copolymers [172]. The authors observed that the addition of copolymers to a phenol/Laponite ® solution led to the replacement of the organic material by the PEO-PPO-PEO.…”

Aqueous phase/nanoparticles interface: hydroxypropyl cellulose adsorption and desorption triggered by temperature and inorganic salts

“…Several studies have been devoted to the physico-chemical characterization of aqueous nanoclay dispersions in the presence of adsorbing species. [13][14][15][16] Laponite RD is a synthetic clay that forms charge-stabilized colloidal dispersion in water. 17 The net charge of a single particle is negative and it is due to the negatively charged faces and slightly positive edge.…”

Pickering emulsions stabilized by novel clay–hydrophobin synergism

“…17. The clay Laponite XLG 22 was purchased from Rockwood Clay Additives GmbH, Moosburg. Polydimethylsiloxane (PDMS) was purchased from Shinetsu Kagaku, Tokyo.…”