system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a theoretical limit on how long carbon chains can be?
gpt
Non-reusable shopping bags are chains of polyethylene thousands of atoms long. UMHWPE chains can be hundreds of thousands of atoms long.

Usually polymer size is expressed as molecular weight in Daltons. So take the highest molecular weight polymers you can find and divide by the mass of a subunit, which would be 14 Daltons for polyethylene (a carbon and two hydrogens).