Self-Assembly of Brush Block Copolymer Photonic Crystals Featuring Low Tg Side Chains

Brush block copolymers, which feature polymeric side chains grafted to a linear backbone, display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. Using ruthenium-mediated ring opening metathesis polymn. (ROMP) of norbornenefunctionalized macromonomers, our group has demonstrated the synthesis of brush block copolymers that behave as photonic crystals. Previous work has shown that the frequency of reflected light can be tuned by varying the backbone d.p. or blending in polymer additives. However, the impact of side chain properties on self-assembly and photonic behavior remains poorly understood. Herein, we report a series of block copolymers featuring poly(dimethylsiloxane) (PDMS) and poly(trimethylene carbonate) (PTMC) side chains. These components were selected to investigate photonic crystal self-assembly for a brush block copolymer featuring side chains with low glass transition temps. (T_g = -125°C for PDMS, and T_g = -15°C for PTMC). The morphologies and photonic properties of these materials will be discussed.