Synthesis and Characterization of Poly(ethylene terephthalate)/Modified Lithium-Aluminum-Layered Double Hydroxide Nanocomposites Prepared Using In-situ Polymerization

Layered double hydroxides are a type of layered stacked compound, which can be intercalated with organic-molecule modifiers. An ion-exchange process for layered double hydroxide (LDH) was used to intercalate water-soluble sulfanilic acid salt (SAS) and dimethyl 5-sulfoisopthalate (DMSI) into lithium aluminum layered double hydroxides (LiAl LDHs). In this work, a hydrothermal process was used to modify LiAl LDHs, and the modified LiAl LDHs were treated with either SAS or DMSI through an ion-exchange process and were then intercalated using bis-hydroxyethylene terephthalate (BHET). The results indicate that the modified LiAl LDHs improved the interlayer compatibility between the PET and LiAl LDH layers; thus, enabling the oligomer molecules to more easily enter the gallery of the LiAl LDH layers so that polymer chains could be included between the LDH layers during polymerization of the matrix. The better barrier, mechanical properties, and thermal stability of these new types of PET nanocomposites are discussed.