Block copolymers find convenient use as architecture-directing agents during the assembly of periodic mesoporous organosilicas (PMOs). Here, I will describe new architecture-directing agents based on poly(N,N-dimethylacrylamide)-block-poly(styrene) block copolymers (BCPs) that allow PMOs to be generated with independently tunable porosity (up to ~80%) and pore size (10–25 nm). In our investigation, we identified a universal packing limit for spherical BCP porogens in the assembled films. Beyond this limit and regardless of pore dimensions, both porogen packing and in turn pore structure after thermal processing showed significant deviations away from simple close-packed lattices. We were able to gain insight into this order-disorder transition above the BCP packing limit using both scattering techniques and high resolution STEM tomography. As a result of their well-formed architectures and exceptionally high porosity, our PMOs gave dielectric constants of 1.2 and 1.5 above and below BCP packing limits, respectively, indicating exciting new avenues for these materials as low-k dielectrics.

Block copolymer packing limits and interfacial reconfigurability in the assembly of periodic mesoporous organosilicas

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.