Novel in situ synthesis in the preparation of ultraviolet‐curable nanocomposite barrier coatings

Abstract

Ultraviolet-curable nanocomposites containing organically modified nanoclays were prepared to serve as barrier coatings against oxygen and water permeation. A novel in situ synthesis technique was used to produce well-dispersed clays in an unsaturated polyester polymer before crosslinking. The in situ dispersion route was compared with nanocomposites prepared by mixing and sonication for several levels of nanoclay loading (1, 2, 5, and 10 wt %). The comparison of nanocomposite properties prepared from each processing method demonstrated that the in situ preparation technique led to better clay disper-sion as verified by transmission electron microscopy. The in situ route for nanoclay dispersion produced nanocomposites with lower water vapor transmission and permeability compared with the sonicated dispersion method. The impact on cure characteristics, mechanical properties, thermal stability, and optical clarity of the nanocomposites were also compared.

Gas barrier properties of polymer/clay nanocomposites

“…76 There are three possible morphologies within polymer/clay nanocomposite systems: phase-separated, intercalated, and exfoliated (see Fig. 79 In exfoliated nanocomposites, the clay layers are completely separated and dispersed individually within the continuous polymer matrix. 16,40,77 Within phase-separated nanocomposites, clay tactoids are formed throughout the matrix and no separation of clay nanoplatelets occurs.…”

“…Polymer chains surround clay nanoplatelets but do not penetrate between the clay layers. 79 The drawback of clays is the incompatibility between hydrophilic clay and hydrophobic polymer, which oen causes agglomeration of clay mineral in the polymer matrix. In intercalated nanocomposites, some of the polymer molecular has penetrated the interlayer galleries of the clay tactoids.…”

“…Besides, compatibilizing agent is also considered to help synthesizing polymer/clay nanocomposites. 5,79 Although, in situ polymerization may form an exfoliated nanocomposite but the clay platelets would recover the stacked structure in the subsequent melt forming process. The compatibilizing agent increases interfacial interaction between organophilic clay and hydrophobic polymer matrix.…”

Effect of surface modified TiO2 nanoparticles on thermal, barrier and mechanical properties of long oil alkyd resin-based coatings

“…On the other hand, the filler particles, compatible with polymer matrix and well dispersed in it, can be applied as good strategy to improve barrier properties of organic coatings [45][46][47]. The presence of NPs enhances the degree of tortuosity of the permeating molecules diffusion path through the polymer, by occupying the free volume within the polymer.…”

Polymer/clay nanocomposite plasticization: Elucidating the influence of quaternary alkylammonium organic modifiers

“…40 To explore these unanticipated results, the goal of this study was to isolate the impact of alkylammonium ions used in layered silicate modification on the properties of the same polyester and coatings systems previously developed. 40 To explore these unanticipated results, the goal of this study was to isolate the impact of alkylammonium ions used in layered silicate modification on the properties of the same polyester and coatings systems previously developed.…”