Compostable sio2 thin film barrier coating for moisture protection

Overview

This solution is an ultra-barrier thin film coating composed of silicon dioxide (SiO2) deposited via atmospheric plasma onto metallized surfaces. The coating is designed to function as a compostable top layer that achieves water vapor transmission rates (WVTR) below 0.3 g/m2/day under accelerated aging conditions of 38°C and 90% relative humidity. The technology addresses a critical market need for high-performance moisture barriers that also meet compostability requirements, enabling applications in sustainable food packaging, compostable electronics, and environmentally responsible encapsulation of sensitive devices such as solar cells.

Technical specifications

Key features:

• SiO2 thin film deposited via atmospheric plasma, compatible with heat-sensitive substrates and metal surfaces
• Target film thickness of 500nm, building on demonstrated 100nm films achieving 0.8 g/m2/day WVTR
• Single-layer architecture for primary performance pathway
• Fallback three-layer barrier structure (SiO2/organosilicate/SiO2, 300nm total) achieving WVTR as low as ~10-3 g/m2/day with organic constituents below 1% to maintain compostability per ASTM6400 6.3.2
• Compostable material composition suitable for end-of-life environmental compliance
• WVTR validated using optical calcium corrosion testing under controlled temperature and humidity aging conditions

How it works:

The SiO2 film acts as a dense inorganic barrier that blocks water vapor permeation. Increasing film thickness substantially reduces WVTR, and the three-layer sandwich structure further reduces permeation by interrupting continuous diffusion pathways. The atmospheric plasma deposition process enables coating on temperature-sensitive substrates and existing metallized layers without thermal damage, making it suitable for roll-to-roll manufacturing of flexible products.

Technology readiness level

The technology is at an early-to-mid stage of development. A 100nm SiO2 film has been demonstrated with a measured WVTR of 0.8 g/m2/day, and the team is confident that increasing thickness to 500nm will meet the 0.3 g/m2/day target. Validation has been performed using optical calcium testing on four samples in controlled environmental aging chambers. Next steps include systematic thickness optimization studies, followed by engineering validation of mechanical durability (hardness and scratch-resistance) required for top coating functionality. The three-layer fallback architecture has already been demonstrated to achieve ultra-low WVTR, providing a clear pathway if single-layer optimization is insufficient.