Controlled synthesis of train-structured montmorillonite/layered double hydroxide nanocomposites by regulating the hydrolysis of polylactic acid

Two-dimensional nanosheets obtained by exfoliation can assemble into new functional nanomaterial. One of the critical challenges is developing an efficient method to make the layered composite complete exfoliation, and another is regulating and controlling nanosheets assembly to obtain the nanocomposite with specific structure. In this article, the platelets of layered double hydroxides (LDH) and montmorillonite (MMT) are exfoliated completely and efficiently in polylactic acid (PLA) by melting blend for 10 min, and the monolayers of MMT or LDH can store stably in PLA for a long time. A new well-organized layered nanocomposite containing the nanosheets of LDH and MMT was gained by being exfoliated and assembling. The structure of MMT/LDH nanocomposite not only holds a periodically alternating structure, but also possesses a train structure, and the formation mechanism of train structure is proposed at the first time; furthermore, the structure of MMT/LDH could be regulated and controlled. Fortunately, even being exfoliated and assembled, MMT nanosheet or LDH nanosheet was not destroyed. The MMT/LDH nanocomposite with expectant structure can be obtained by this efficient and environmentally friendly method, and this method may easily be extended to other layered materials.