Polcore is a plastic material and so, at first sight, it sounds much better to use wood instead. However, Polcore is made from 70% reclaimed material and is fully recyclable. The frame will last for generations.
Soft woods like pine attract woodworm. Hardwoods are more resilient. Wood contains acid which can damage a print and is why we use a conservation barrier board to protect the print.
The one thing we do not use is MDF with a foil coating. This also contains acid but with a thin foil coat has a much shorter life expectancy.