(17b) Multilayer Reactive Barrier Materials

We present models with numerical and analytic solutions to estimate key barrier parameters of multilayer, reactive polymer films. Polymer films with immobile and irreversible reactive sites can be effective barrier materials for packaging applications, for example, for oxygen sensitive foodstuffs or organic electronics. Ideal materials will have both good mechanical and barrier properties. Scavenging polymers, such as polybutadiene, typically have poor mechanical properties. Multilayering of scavenging polymers with good supporting materials, such as poly(ethylene terephthalate) and polystyrene, is a strategy to achieve both desirable properties.

The solutions to the models presented predict the time varying flux and time lag through multilayer films. The barrier properties of multi-layer reactive membranes are compared to results for polymer blends of equivalent scavenger and structural polymers. Results are presented for a range of material properties and design variables consistent with packaging applications. Complete experimental characterization of multi-layer materials would require a large number of experiments due to the multiple degrees of freedom in the problem. In addition, a viable barrier material for oxygen should prevent significant flux for months or years, making experimental characterization impractical. The results presented here enable optimization of material design by predicting the behavior of multilayer systems of various configurations with minimal experimental data.