Accession Number : ADA183657

Title :   Transition-Metal-Catalyzed Polymerization of Silazanes as a Route to the Preparation of Silicon-Carbide-Nitride Fibers. Advanced Methods for the Preparation of Preceramic Polymers and Their Transformation into Silicon Nitride Fibers.

Descriptive Note : Final rept.,

Corporate Author : SRI INTERNATIONAL MENLO PARK CA

Personal Author(s) : Laine,Richard M ; Blum,Yigal D ; Chow,Andrea W ; Schwartz,Kenneth B

PDF Url : ADA183657

Report Date : Jan 1987

Pagination or Media Count : 5

Abstract : The primary goal for both projects is to develop synthetic routes to tractable preceramic polysilazanes that can be spun into preceramic fibers and pyrolytically transformed into silicon nitride or silicon carbide-nitride fibers based on novel catalytic processes discovered at SRI. The research program is divided into three separate Tasks. Our efforts, in the first task, are directed towards optimizing the polymer synthesis process(es) through detailed studies of the kinetics and mechanisms of the catalytic reaction(s) that promote polymer formation. Research in the second task focusses on rheological characterization of polymers produced in the first task and development and refinement of polymer spinning procedures. The third task efforts are concerned with optimizing the process whereby the polysilazanes produced in Task 1 and shaped in Task 2 are pyrolytically transformed into ceramic materials and the characterization of the ceram ic products. In the course of our studies, we have detailed the kinetics and mechanisms of the transition metal catalyzed cleavage of bonds and the dehydrocoupling process whereby silicon nitrogen bonds are formed from silicon nitrogen and nitrogen hydrogen bonds using simple model systems. We have identified ruthenium as the best catalyst for dehydrocoupling following a survey of potential transition metal catalysts.

Descriptors :   *CERAMIC MATERIALS, *SILICON COMPOUNDS, *POLYMERIZATION, CATALYSTS, CLEAVAGE, FIBERS, HYDROGEN BONDS, NITROGEN, POLYMERS, REFINING, RUTHENIUM, SILICON, SILICON NITRIDES, TRANSITION METALS, SYNTHESIS(CHEMISTRY), CARBON FIBERS, SILICON CARBIDES, COUPLING(INTERACTION), CATALYSIS

Subject Categories : Polymer Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE