Synthesis and characterization of block copolymer/ceramic precursor nanocomposites based on a polysilazane

Abstract

The amphiphilic block copolymer poly(isoprene‐block‐ethylene oxide) was used as a structure‐directing agent for a polysilazane preceramic polymer commercially known as Ceraset. Two block copolymers of different molecular weights and poly(ethylene oxide) weight fractions with body‐centered cubic sphere and hexagonal cylinder morphologies were used. To both polymers, 50 wt % of the silazane oligomer (Ceraset) was added. The resulting composites were cast into films and characterized by small‐angle X‐ray scattering and transmission electron microscopy. The silazane was chemically compatible with the poly(ethylene oxide) microdomains of the block copolymer, and this resulted in a swelling of those domains. After the cooperative self‐assembly of the block copolymer and Ceraset, for both systems the structure was permanently set in the lamellar morphology by the crosslinking of the silazane oligomer with a radical initiator at 120 °C. These results suggest that the use of block copolymer mesophases may provide a simple and easily controlled pathway for the preparation of various high‐temperature SiCN‐type ceramic mesostructures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3346–3350, 2003

Composition and Morphology Control in Ordered Mesostructured High‐Temperature Ceramics from Block Copolymer Mesophases

“…To this end we first showed that the amphiphilic diblock copolymer polyisoprene-block-poly(ethylene oxide) (PI-b-PEO) can serve as a structure-directing agent for poly (ureamethylvinyl)silazane (PUMVS), commercially known as Ceraset. [14] In 2004 we demonstrated, to the best of our knowledge for the first time, that mesoporous high-temperature ceramic materials stable up to 1 500 8C can be prepared based on a related approach using polyisoprene-blockpoly(dimethylamino ethyl methacrylate) (PI-b-PDMAEMA) as the structure-directing agent for PUMVS. [15] Both the molecular structure of the block copolymer and the preceramic polymer, as well as details of the heat treatment to convert the liquid PUMVS precursor into a ceramic are shown in Figure 1.…”

Synthesis of Inorganic–Organic Diblock Copolymers as a Precursor of Ordered Mesoporous SiCN Ceramic

“…Compared with other synthetic processes, for example, using organic block copolymers as a template, [15,16] the prepared SiCN product exhibited a higher BET surface area with high temperature stability. The observed high BET surface area even at 1400°C clearly demonstrates that an inorganic-organic block copolymer could be the most reliable route with essential design of curing chemistry to prepare versatile mesoporous nonoxide ceramics with excellent thermal stability.…”

“…[9][10][11][12][13][14] Wiesner and co-workers reported mesoporous SiCN ceramic materials with an organic diblock copolymer amphiphile through the preferential interaction of inorganic precursors. [15,16] On the other hand, the complete removal of an organic template by pyrolysis can cause serious volume shrinkage, which can reduce the mechanical and dimensional stability of the ceramic products obtained. Manners and co-workers reported the formation of nanostructures using poly(ferrocenylethylmethylsilane)-block-poly(styrene) as an organic-organometallic block copolymer.…”

“…Furthermore, a weak higher ordered peak at 1.95°is convincing evidence for a high level of ordering. It is most likely that the preservation of ordered mesoporous structures even with a thin solid wall at high temperatures is mainly attributed to the lower organic portion of this block copolymer, unlike the organic-organic block copolymers [14][15][16] and the reported inorganic-organic block copolymers.…”

Research on the frontiers of materials science: The impact of nanotechnology on new material development

“…Temple et al [22] have shown pyrolitic formation of ordered nanoscopic, non-oxide ceramic structures from self-assembly of poly(styrene-b-ferrocenylsilane) block co-polymers at 600 1C. Wiesner et al [23] have demonstrated that block co-polymers can be used as structuredirecting agents to template silicon carbonitride ceramic precursors such as polysilazane. However, there are no examples in the published literature showing the ability to maintain nanoscale control of ordered structures up to the extreme temperatures where these materials will be used.…”