Tunable interlayer hydrophobicity in a nanostructured high charge organo-mica

Abstract

A tunable hydrophobicity, from a fully hydrophobic medium to an amphiphilic quasi-solution, has been obtained in the interlayer space of a synthetic high charged mica by ion exchange reaction with amine cations. The structural and intercalation properties of the hybrids after the exchange with the n-alkylammonium cations: [RNH 3 ] + , [RNH(CH 3 ) 2 ] + and [RN(CH 3 ] 3 + with C16 alkyl chain length have been determined by termogravimetric/differential scanning calorimetry analysis (TGA-DSC) and mass spectrometry (MS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM) has been used as a complementary technique to provide new insights into the morphology of the exchanged products. Coverage and cation distribution have been correlated with layer charge and

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“…TG experiments of the initial Mica-4 exchanged with C 16 H 33 NH(CH 3 ) 2 + ions showed a ratio of replacement of 50% of the interlayer Na + (~38% mass loss). The hybrid material was then organized in a regularly intercalated layered phase, with surfactant cations and sodium cations in an associative distribution, forming hydrophobic and hydrophilic independent clusters in the interlayer space of the aluminosilicate [17]. The composition of the interlayer agrees with the results extrapolated from the TEM image and the XRD diagram included in Figure 1.…”

“…It was confirmed by TG measurements. Additionally, the formation of a heterostructure or a segregation arrangement can be discarded by the absence of a second basal reflection family corresponding to hydrated sodium in the interlayer [17]. The presence of organic cations on the C16H33NH(CH3)2 + -mica and C16H33NH3 + -mica samples was also corroborated by infrared measurements, and the results are included as Supplementary Materials.…”

“…Controlled adsorption of the organics leads to tunable hydrophobicity in the interlayer space of the hybrid material. This provides the possibility to choose the optimal interface nature, as is required for a variety of applications, from a fully hydrophobic medium to an amphiphilic quasi-solution [17]. Specifically, an organo-mica with a homogeneous single-phase organic-clay is formed from an exchange reaction with long primary n-alkylammonium cations.…”

“…For that purpose, the swellable high charge mica Na-4-Mica was exchanged with the tertiary R-N(CH 3 ) 2 amine with alkyl length R = 16, in an acidic medium. When the Na-4-Mica is exchanged with the tertiary ammonium cation [RNH(CH 3 ) 2 ] + , R = 16, the exchange capacity is not fully satisfied, and a homogeneous heteroionic structure is formed with mixed organic/inorganic cations in the same interlayer [17]. The organo-mica, C 16 H 33 NH 3 + -mica, was also synthesized via cation exchange reaction.…”

“…The organo-mica, C 16 H 33 NH 3 + -mica, was also synthesized via cation exchange reaction. The length of the primary ammonium cation was carefully chosen to assure that van der Waals interactions between alkyl chains would be strong enough to allow a quantitative uptake of the surfactant cations in this sample [17]. This organo-mica has been previously reported to be an improved adsorbent material of hydrophobic VOCs for water decontamination [10].…”