Enhancement of barrier property of plastic substrate by intra-gallery polymerization for nanocomposites

2-(Methacryloyloxy)ethyl(4-benzoylbenzyl) dimethyl ammonium bromide (MDAB) was successfully synthesized and used as a photo initiator and intercalation agent to induce intra-gallery polymerization. MDAB effectively replaced the sodium ions in the inter-gallery layer of sodium montmorillonite (Na ⁺-MMT) by the cationic exchange reaction, which was confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The modification of Na⁺-MMT with MDAB increased the d-spacing, with the MDAB/Na⁺-MMT ratio of 2:1 doubling the initial d-spacing. Clay with modified MDAB was used to make a nanocomposite layer formation on a poly(ethylene naphthalate) (PEN) substrate by the photopolymerization of bisphenol A type epoxy diacrylate (EpA). Intra-gallery polymerization using MDAB attained more effective intercalation and better dispersion of the clay than extra-gallery polymerization using commercial organoclay. The clay content affected the barrier properties, and the best result was obtained at 5 wt% clay content, producing a water vapor transmission rate (WVTR) of 0.39 g/m ² day while maintaining the optical transmittance. [Figure not available: see fulltext.]