Preceramic organosilazane polymers
AssigneeMassachusetts Institute of Technology
InventorsDietmar Seyferth, Gary H. Wiseman
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Abstract
A preceramic polymer which is a polysilazane is described. It is made by reacting an organodihalosilane with ammonia to form an ammonolysis product, and treating the ammonolysis product with a basic catalyst capable of deprotonating an NH group that is adjacent to an SiH group to form said polymer. The polymer is preferrably further treated with an electrophilic reagent. These polymers are useful for making various ceramic products.
Claims33
A polysilazane comprising:
- a plurality of precursor residues having repeating units of the formula:
- ##STR11## said residues being linked together by Si.sub.2 N.sub.2 bridges having the formula ##STR12## wherein:
- R is hydrogen, a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkoxy group having from 1 to about 6 carbon atoms, a substituted or unstubstituted vinyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group;
- and
- n is an integer greater than 1;
- said residue being cyclic or linear.
The polysilazane polymer comprising cyclic precursor residues, said polymer having the structural formula:
- ##STR13## R is a hydrogen, a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkoxy group having from 1 to about 6 carbon atoms, a substituted or unsubstituted vinyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group;
- and
- x and y are each independently 0 or a positive integer;
- m is an integer greater than 1;
- and
- x and y can be the same or different from each cyclic precursor residue in the polymer chain.
A method for preparing an organosilazane polymer, said method comprising:
- reacting in solution anhydrous ammonia with RSiHX.sub.2 where R is hydrogen, a lower alkyl group having from 1 to about 6 carbon atoms or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, and x is a halogen, thereby forming a mixture of cyclic and/or linear precursors and reacting said precursors in the presence of a basic catalyst capable of deprotonating the hydrogen from a nitrogen atom adjacent to a silicon atom to form an Si.sub.2 N.sub.2 bridge, thereby forming said organosilazane polymer.
A polymethylsilazane comprising a plurality of residues of cyclic monomers having the formula ##STR14## wherein n is an integer greater than 1 and each residue in said polymethylsilazane can be the same or different.
An organosilazane polymer comprising structural units of RSiHNH, RSiHNCH.sub.3, and RSiN and represented by the formula (RSiHNH).sub.a (RSiHNCH.sub.3).sub.b (RSiN).sub.c, where 1+b+c=1 and R is hydrogen, a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkoxy group having from 1 to about 6 carbon atoms, a substituted or unsubstituted vinyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group.
An organosilazane polyemr comprising structural units of RSiHNH, RSiHNM, and RSiN, and represented by the formula, (RSiHNH).sub.1 (RSiHNM).sub.b (RSiN).sub.c, where a+b+c=1;
- R is hydrogen, a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkoxy group having from 1 to about 6 carbon atoms, a substituted or unsubstituted vinyl group, a substituted or unsubstituted allyl group, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group;
- and
- M is an alkali metal or one-half equivalent of an alkaline earth metal.
A polysilazane made by reacting an organodihalosilane with ammonia to form an ammonolysis product, and treating the ammonolysis product with a basic catalyst which is capable of deprotonating an NH group that is adjacent to an SiH group to form said polysilazane.
Dependencies are inferred from the claim text.