A composition and method for making polymeric foam comprising nanocellular domains is provided. The nanocellular domains in the polymeric foam increase the R-value of the polymeric foam product and improve thermal insulation performance. The polymeric foam having the nanocellular domains may be formed using a carbon dioxide-based blowing agent. The polymeric foam having the nanocellular domains can be produced on production- scale equipment in amounts suitable for large-scale applications.