We introduce a mild and efficient avenue to induce the folding of single chain polymer nanoparticles (SCNPs) using visible light. The versatility of the method is based on three folding mechanisms exploiting tetrazole chemistry, i.e., nitrile imine-mediated tetrazole-ene cycloaddition (NITEC), nitrile imine carboxylic acid ligation (NICAL) as well as nitrile imine self-dimerization. To our knowledge, this visible light driven approach is the to-date mildest avenue to fold single polymer chains into compact particles using light.

We introduce a facile photoinduced self-reporting crosslinking methodology for the compaction of polymer chains in highly diluted solution.