Poly(phthalaldehyde) was first reported in 1967 by Chuji Aso and Sanae Tagami from the department of Organic Synthesis at Kyushu University by an addition homopolymerization reaction of aromatic o-phthalaldehyde. This polymer, consisting of a polyacetal main chain, is still to date, the only aromatic aldehyde that can be homopolymerized through a chain-growth polymerization method. It is a white brittle solid with a low ceiling temperature and significant self-immolative properties. It has gathered significant attention in recent years especially in the development of novel responsive materials and applications.