Our technology-driven society continues to advance, and with it the demand for various high-function plastics also advances, calling for precision-engineered polymers with few defects in their structures even at the molecular level. People’s lives have come to strongly rely upon these plastics, but in recent decades have we also come to recognize their negative aspects in the form of the environmental and resource crises. It is against this backdrop that a new method of efficient and precise control over polymer structure has been developed - the use of porous materials called ‘MOFs’ as nano-sized ‘factories’. With this new technology, desired polymers can be supplied and utilized effectively, and we envision a future where they may also be reclaimed post-use then re-circulated.