Ultrasound-Assisted Synthesis, Characterization, and Applications of Halloysite-Polymer Nanocomposites

Abstract

Nanocomposites have been receiving growing interest in research as these materials display unique and attractive properties. Halloysite nanotubes are naturally occurring clay minerals and offers an inexpensive, low-tech alternative that is morphologically similar to multiwalled CNTs. In this work, ultrasound-assisted synthesis of HNT-polymer nanocomposites using three different routes i.e., solution blending, emulsion polymerization and mini-emulsion polymerization is presented. The interaction of HNTs with the polymer and their dispersion in the polymer matrix are vital in enhancing the properties of polymers. To achieve better interaction between HNTs and polymers the surface of HNTs was chemically modified with surfactant (Cetyl trimethylammonium bromide) and silane (γ-MPS) coupling agent. To achieve better dispersion of HNTs into polymer matrix ultrasound-assistance was utilized. HNT-polymer nanocomposites were characterized using different characterization techniques to understand their structure, morphology, functional, mechanical and thermal properties. It was observed that the surface modification of HNTs along with use of ultrasound for the process resulted in improvement in the properties of nanocomposites. HNT-polymer nanocomposites were used for two types of applications. Firstly, they were applied as protective coatings to different types of soda-lime glasses. These coatings displayed good thermal stability, mechanical strength, and hydrophobicity. They ensured better protection of the surface and the increased durability of the soda-lime glass. Next, the HNT-polymer nanocomposites was used for the fabrication of membranes for treatment of water. Two stage filtration unit comprised of nanoporous and microporous membrane was developed. The fabricated membranes displayed high water flux, great solute rejection, long-term stability of water flux, good rejection, and excellent mechanical and thermal properties. Overall, HNT-based polymer nanocomposites have greater potential for various applications in environmental construction and automobile industries.