title: Ordered mesoporous ceramics stable up to 1500 degrees C from diblock copolymer mesophases.
abstract: In the present study, a poly(isoprene-block-dimethylamino ethyl methacrylate) diblock copolymer (PI-b-PDMAEMA) is used to structure-direct a polysilazane pre-ceramic polymer, commercially known as Ceraset. To the polymer was added a 2-fold excess in weight of the silazane oligomer (Ceraset). The resulting composite was cast into films, and after cooperative self-assembly of block copolymer and Ceraset, the structure was permanently set in the hexagonal columnar morphology, as evidenced by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Cross-linking of the silazane oligomer was achieved with a radical initiator at 120 degrees C. Upon heating of the composite to 1500 degrees C under nitrogen, the structure is preserved and a mesoporous ceramic material is obtained, as demonstrated by SAXS and TEM. The pores are open and accessible, as evidenced by nitrogen sorption/desorption measurements indicating a surface area of about 51 m2 g-1 and a pore diameter of 13 nm, consistent with TEM analysis. These results suggest that the use of block copolymer mesophases may provide a simple, easily controlled pathway for the preparation of various high-temperature ceramic mesostructures.
authors.affiliation: Department of Materials Science and Engineering, Cornell University, 329 Bard Hall, Ithaca, NY 14853, USA.
authors.forename: Marleen
authors.initials: M
authors.lastname: Kamperman
authors.forename: Carlos B W
authors.initials: CB
authors.lastname: Garcia
authors.forename: Phong
authors.initials: P
authors.lastname: Du
authors.forename: Hooisweng
authors.initials: H
authors.lastname: Ow
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wiesner