Interfacial Modification of Magnetic Montmorillonite (MMT) Using Covalently Assembled LbL Multilayers

Abstract

Constructing stable and reliable interfaces around pseudo two-dimensional clay materials is a key process in achieving advanced and reliable performance of related composite materials. However, the effective surface modification of pseudo two-dimensional clay has been a challenging research topic. In this study, we have developed an effective and facile method for the interfacial modification of magnetic montmorillonite (MMT) nanocomposite by using covalent layer-by-layer (LbL) assembly. The method involves conventional LbL assembly around the magnetic MMT followed by infiltration of a bifunctional photoactive small molecule and then covalent cross-linking of the LbL multilayers upon UV irradiation. After covalent LbL modification, the nanocomposite presented ample organic species around its interfaces and displayed stable organic interfaces even in extreme solution conditions such as in basic (pH =14) solutions. The covalent cross-linking of the multilayers proved to be indispensable in keeping the LbL multilayers stable around the MMT composites. After modification, the composite particles kept their magnetic properties. In addition, the release profile of the composite particles for methyl blue indicated that the composite particles preserved the capacity to carry loads and release them in retarded speed. This method will potentially integrate the merits of LbL multilayers with MMT to achieve advanced functional materials.

Fluorescence microscopy as an alternative to electron microscopy for microscale dispersion evaluation of organic–inorganic composites

“…The X-ray diffraction patterns of Na + -MMT and TPE-DTAB-modified MMT were measured to study the structure change of MMT. It is known that 2 θ change in the range of 2°–10° for layered silicates indicated the formation of new ordered intercalated cationic layers 47 48 49 . As shown in Fig.…”

PAH/DAS covalently cross-linked layer-by-layer multilayers: a “nano-net” superstratum immobilizes nanoparticles and remains permeable to small molecules

“…[21][22][23] In this study, the decomposition of DAS was evident by the decrease of the absorbance to around 340 nm (Fig. Previous studies have shown that upon UV irradiation, the photo-active DAS decomposes into nitrene species and forms covalent linkages with adjacent C-H, O-H, and N-H functional groups.…”

“…In fact, LbL multilayers containing MP SiO 2 NPs are highly appealing as functional devices, but strategies for the fabrication of covalently stabilized multilayers including MP SiO 2 NPs are still lacking. 23 The uncross-linked multilayers disassembled in basic treatment ( Fig. 4.…”

Quaternized chitosan/montmorillonite nanocomposite resin and its adsorption behavior

“…The result indicates that the quaternized modification on chitosan resins has happened. Moreover, compared with quaternized chitosan resin, the spectrum of QCMR1 shows adsorption band of montmorillonite, they were Si-O-Si and Al-O-Si bending vibration bands at 527 and 472 cm −1 , respectively [21]. It indicates that MMT was included in the resins.…”