Preceramic organosilicon-boron polymers

Claim 2

A preceramic polymer characterised in that it is the reaction product of: (a) an organosilicon oligomer or polymer containing a plurality of Si-H or Si-N functional groups, with (b) a borane wherein the molar ratio of organosilicon polymer repeat units to borane is 15 or less.

Claim 3

The preceramic polymer of claim 1, characterised in that the organosilicon oligomer or polymer having a plurality of Si-H and/or Si-N functional groups is an organic polysilazane.

Claim 4

The preceramic polymer of claim 1, characterised in that the organosilicon oligomer or polymer containing a plurality of Si-H and/or Si-N functional groups is a polysilazane of the formula [R¹R²SiNR³] n , wherein R¹, R², and R³ are H or an organic group, and R¹, R², and R³ may all be the same or different and n is greater than 1.

Claim 5

The preceramic polymer of claim 3, characterised in that the organic group is a lower alkyl group having from 1 to 8 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 8 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to 8 carbon atoms or a substituted or unsubstituted lower aryl group having from 6 to 10 carbon atoms, and wherein the substituents can be a lower alkyl group or a heteroatom.

Claim 6

The preceramic polymer of claim 2 or 4, characterised in that the borane has 1, 2 or 3 H substituents per B.

Claim 7

The preceramic polymer of claim 4 or 5, wherein the borane is selected from H₃B· Lewis base complexes, B₂H₆, RBH₂· Lewis base complexes, wherein R is an alkyl group, R₂B₂H₄, R¹R²NBH₂· Lewis base complexes, wherein R¹ and R² are H, a lower alkyl group having from 1 to about 8 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 8 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to about 8 carbon atoms or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, wherein the substituents can be a lower alkyl group or a heteroatom, and R¹ and R² may be the same or different, and uncomplexed aminoboranes.

Claim 8

The preceramic polymer of claim 1, 2, 3 or 6 characterised in that the organosilicon oligomer or polymer have been reacted with the borane in an organic solvent.

Claim 9

The preceramic polymer of any preceding claim characterised in that the molar ratio of organosilicon oligomer or polymer repeat units to borane is 10 or less.

Claim 10

The preceramic polymer of claim 3, characterised in that the molar ratio of [R¹R²SiNR³]/BH₃ is 10 or less.

Claim 11

The preceramic polymer of claim 7, characterised in that it is soluble in an organic solvent.

Claim 12

The preceramic polymer of claim 4, characterised in that it is soluble in an organic solvent.

Claim 13

The preceramic polymer of claim 4, characterised in that at least one of R¹, R², and R³ is a lower alkyl group.

Claim 14

The preceramic polymer of claim 12, characterised in that the lower alkyl group is CH₃.

Claim 15

The preceramic polymer of claim 2, characterised in that said organosilicon polymer having a plurality of Si-H and/or Si-N functional groups is a mixture of organic oligosilazanes or polysilazanes.

Claim 16

The preceramic polymer of claim 4 or 7, characterised in that the polysilazane is a mixture of oligosilazanes or polysilazanes.

Claim 17

The preceramic polymer of claim 15, characterised in that the mixture of oligosilazanes or polysilazanes is selected from (R¹R²SiNH) n , (R³R⁴SiNH) n , (R³Si(NH) 1.5 ) n , wherein R⁴ is defined as for R¹, R², and R³ above, but may be the same as or different from any of R¹, R², and R³.

Claim 18

The preceramic polymer of claim 14 or 15 characterised in that the mixture of oligosilazanes or polysilazanes is the product of an initial ammonolysis reaction.

Claim 19

The preceramic polymer of claim 17, characterised in that the mixture of oligosilazanes or polysilazanes is CH₃SiHCl₂/(CH₃)₂SiCl₂ or CH₃SiHCl₂/CH₃(CH₂=CH)SiCl₂ mixtures.

Claim 20

The preceramic polymer of claim 6, characterised in that said borane is selected from the group consisting of H₃B·S(CH₃)₂, H₃B·N(C₂H₅)₃, H₃B·C₅H₅N, H₃B·S(C₂H₅)₂, H₃B·P(CH₃)₃, H₃B·AsPh₃, H₃B·O(CH₃)₂, and H₃B·N≡CCH₃.

Claim 21

The preceramic polymer of claim 2 or 14, characterised in that the organic polysilazane or the mixture of organic oligosilazanes or polysilazanes have been modified by thermal treatment or by treatment with a protic strong acid or an ammonium salt at temperatures ranging from 25°C to 250°C.

Claim 22

A ceramic formed by the pyrolysis of the preceramic polymer of any preceding claim.

Claim 23

The ceramic of claim 21 when formed in an inert gas atmosphere.

Claim 24

The ceramic of claim 21 when formed in an ammonia atmosphere.

Claim 27

A method of making ceramic by the pyrolysis of the preceramic polymer prepared in accordance with claim 24 for a sufficient time and at a sufficient temperature to form said ceramic.