Construction Of Montmorillonite/Carbon Nanotube/Polymer Composite At The Nanoscale Based On Layer-by-layerassembly Technique

Nacre is a kind of natural organic-inorganic hybrid hierarchical compositematerial, consisting of inorganic calcium carbonate (about95%) and organiccompounds (about5%). Inspired by the fact that excellent mechanical performancesof nacre originate from its unique “bricks-mortar” assembly structure, many effortshave been made to address artificial nacre-like materials. As one of interestingattempts to pursue superstrong sandwich-structured nanocomposites, we introduce anadditional “fiber layer” to anchor the “brick layer” and “mortar layer”, expecting thatthe “bricks-mortar” interfacial interactions could be significantly improved.Considering its ability to construct composites at the nanoscale, layer-by-layer (LBL)assembly technique is selected to actualize this idea in this study. The main contentsinclude:(1) Preparation of montmorillonite (MMT)/single-wall carbon nanotube (SWNT)hybridized composites characterized with all inorganic components by using the LBLassembly technique–Electrostatic interaction between MMT and SWNT is used asthe driving force for the preparation. Considering the fact that there are negativecharges on the MMT surface, the NH2-functionalized SWNTs (SWNT-NH2) weresynthesized to provide the positive surface of SWNTs.. Under the optimal assemblyconditions, the thickness of (MMT/SWNT)nmultilayered film grows linearly with arate of6.65nm per (MMT/SWNT) unit. The study on mechanical properties of themultilayered films show that the annealing treatment is an effective way to enhancethe elastic moduli, but it deteriorates the film surface quality. (2) Preparation of (MMT/PDDA/MMT/SWNT)ncomposites with MMT as bricklayer, PDDA as mortar layer, and SWNT-NH2as fiber layer by using the LBLassembly technique–The research results show that the thickness of multilayeredfilms grows linearly with a rate of99.54nm per (MMT/PDDA/MMT/SWNT) unit.The mechanical properties of the films can be enhanced by increasing of numbers ofassembly layers, improving annealing temperature, and/or prolonging annealingtreatment time.(3) Preparation of (MMT/SWNT/PSS/SWNT)ncomposites with MMT as bricklayer, PSS as mortar layer, and SWNT-NH2as fiber layer by using the LBL assemblytechnique–The research results show that the thickness of multilayered films growslinearly with a rate of66.67nm per (MMT/SWNT/PSS/SWNT) unit. Unlike thePDDA composite films, the mechanical properties of PSS composite film decreasewith increasing of the number of assembly layers. Improving annealing temperature isan effective way to enhance the elastic moduli but prolonging of the annealingtreatment time induces the decrease of eleastic moduli possibly resulted from thedegradiation of PSS.