Relationship between optical properties and network topology in gels crosslinked using controlled radical polymerization*

Controlled radical polymerization can be used to prepare crosslinked polymer gels and aerogels with a variety of unique features: tunable optical transparency, high specific surface area, controlled pore size, and narrow pore size distribution. Such materials enable a range of applications in size- and interaction-selective separations, catalysis and photocatalysis, and thermally insulating materials. We demonstrate that controlled radical polymerization can be used to control network topology, which directly impacts the optical properties and pore structure of crosslinked polymer gels. Two novel methods to control the degree of “livingness” in the gelation reaction are reported. The degree of livingness in the gelation was used to tune the visible light transmittance of a 3 mm gel from 0 % to >70 %. Porous aerogels can be produced from the solvated gels by solvent evaporation at ambient pressure and temperature. Controlled radical gelation led to aerogels with porosities over 60 % and Brunauer Emmett Teller surface areas over 1000 m²/g.