Recyclable paper-based vapor barrier coatings via sequential infiltration synthesis

Overview

This solution addresses a critical challenge in food packaging: creating effective vapor barriers on paper-based materials that remain recyclable. The approach combines thin polymer coatings on paper with Sequential Infiltration Synthesis (SIS) to infuse metal oxide clusters into the polymer's free volume, blocking diffusion of oxygen and water vapor. The resulting barrier coatings are low-cost, lightweight, food-safe, and compatible with standard pulping processes for recycling. This technology offers a sustainable alternative to traditional multi-layer plastic barrier films.

Technical specifications

Core technology: Sequential Infiltration Synthesis (SIS)

• Chemical vapors diffuse into the polymer film and react with organic functional groups (e.g., carbonyl groups) to form covalently linked metal oxide species
• Continued vapor exposure builds metal oxide clusters that naturally fill the polymer's free volume
• The self-terminating process blocks gaseous diffusion at very low inorganic loadings (mg/m²)
• Infused polymer films retain flexibility and are easily removed via standard pulping processes

Key advantages over existing approaches:

• Versus ALD: Atomic Layer Deposition creates excellent barriers (WVTR below 10⁻⁵ g/m²/day) but films are too thin to fill paper voids; SIS achieves comparable barrier performance at practical thicknesses
• Versus standalone polymer films: Polymers like polyester and polyurethane fill paper voids but lack effective barrier properties; SIS infusion transforms them into high-performance barriers
• Compatible with existing polymer-coated paper substrates (polyester, polyurethane)

Technology readiness level

This technology is at an advanced development stage with demonstrated proof-of-concept. Prior studies using gravimetric analysis, infrared spectroscopy, and electron microscopy (SEM/TEM) have validated that SIS terminates at very low inorganic loadings due to diffusion blocking. A development and validation effort is underway with Forge Nano and Argonne to develop and validate recyclable paper-based vapor barriers, including optimization of SIS processing conditions across different inorganic materials and polymers and scale-up efforts using roll-to-roll manufacturing for commercial deployment.