Abstract

There are lots of researches to improve surface functionalization of halloysite nanotube (HNTs). This mini-review is about the enhancement of the surface activity and adsorption capacity of HNTs by amine-terminated dendritic polymers with two strategies: convergent and divergent synthetic routes. For this purpose, HNTs first was reacted through silanization reaction via 3-triethoxysilylpropylamine (APTES) to produce HNTs-NH2. In the divergent method, dendritic amino groups were added onto HNTs by the Michael addition of methyl acrylate (MA) to create half generation and then amidation reaction through ethylene diamine to produce full generation. This step was repeated to the dendritic structure grown onto HNTs step by step till define generation number. In the convergent synthesis route, two different strategies are possible. First, all hydroxyl groups were converted to carboxylic acid groups by dicarboxylic acid materials to produce HNTs-COOH. Then, amine-terminated dendritic materials were grafted onto the carboxylic acid groups attached to HATs. In another method, amine-terminated dendritic materials were reacted with half generation (HNTs-MA) to create full generation. The result reveals that the convergent method has fewer steps than the divergent method, and its results lead to saving cost and energy.

Keywords: Dendrimer; Amine-Terminated group; Halloysite; Functionalization; Divergent; Convergent

Abbreviations: HNTs: Halloysite Nanotubes; MA: Methyl Acrylate