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

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.