Visible Light Induced Solubility Modulation of Polynorbornene Bearing Bridged 1,2-Diketones

We herein report the synthesis and photoinduced solubility modulation of a poly(norbornene) bearing bridged 1,2-diketone units in the repeating unit. Selective irradiation of the n to pi* absorption band of the monomer using a blue LED light source emitting at 455 nm lead to a rapid and quantitative decarbonylation at the diketone bridge, yielding the corresponding anthracene derivative. Identical photoinduced decarbonylation was observed in the polymer obtained from the ring-opening metathesis polymerization (ROMP) of the photoreactive monomer. The polymer displayed photoinduced solubility change wherein irradiation of the polymer solution in various solvent systems with a blue LED light source led to the precipitation of the polymer, producing polymer nanoparticles. The solubility change is attributed to the change in the free volume of the polymer and constitutes a method of photoinduced solubility modulation in which only gaseous byproducts are generated from the photocleavage reaction.

Automated summary

The study reports the synthesis of a polymer with bridged 1,2-diketone units and the photoinduced solubility modulation method. By irradiating the monomer with a blue LED light source at a specific wavelength, rapid change in molecular structure and solubility modulation were achieved.