Block Copolymer Packing Limits and Interfacial Reconfigurability in the Assembly of Periodic Mesoporous Organosilicas. (26th May 2015)

• Record Type: Journal Article
• Authors: Wills, Andrew W.; Michalak, David J.; Ercius, Peter; Rosenberg, Ethan R.; Perciano, Talita; Ushizima, Daniela; Runser, Rory; Helms, Brett A.
• Is Part Of: Advanced functional materials. Volume 25:Number 26(2015)
• Page Start: 4120
• Page End: 4128
• Publication Date: 2015-05-26
• Subjects: Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201501059
• Languages: English
• ISSNs: 1616-301X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Here poly(<italic>N, N</italic>‐dimethylacrylamide)‐<italic>block</italic>‐poly(styrene) block copolymer micelles (BCPs) are advanced and applied to assemble periodic mesoporous organosilicas (PMOs) with noncylindrical pores. Using these BCP micelles, it is found that pore dimensions (11–23 nm), wall thicknesses (5–9 nm), and overall porosities (26%–78%) are independently programable, depending only on relative inputs for BCP and matrix former. Notably, the degree of order in all films improves as BCP loading approaches a packing limit of 63 vol%. Beyond this limit and regardless of pore dimensions, both porogen packing in the film and pore structure after thermal processing show significant deviations away from spherical close‐packed lattices. The surprising absence of film collapse in this regime allows here to quantify the evolution of pore structure through the thermally driven interfacial reconfigurability of BCP micelles in the hybrid films when porogen loading exceeds the packing limit by using both scattering techniques and scanning transmission electron microscopy tomography. Finally, the PMOs here give dielectric constants of 1.2 and 1.5 above and below the BCP packing limit, respectively—the lowest ever reported for this matrix material.</p> </abstract>