Polysilazanes and related compositions, processes and uses

Claim 1

A method of producing polysilazanes useful as preceramic polymers and containing at least one newly formed Si--N bond which comprises: (a) providing a precursor containing at least one Si--N bond, catalytically cleaving an Si--N bond in the precursor in the presence of a transition metal catalyst effective to activate Si--N bonds, such cleavage being carried out in the presence of hydrogen or a hydrogen donor, and reacting the cleavage product to produce an initial polysilazane product; or (b) providing one or more reactants which contain an Si--H bond and an N--H bond, and causing reaction to occur between such Si--H and N--H bonds in the presence of a transition metal catalyst effective to activate Si--H and N--H bonds, to produce an initial polysilazane product having at least two Si--N bonds.

Claim 2

A method of producing polysilazanes useful as preceramic polymers and containing at least one newly formed Si--N bond which comprises: (a) providing a precursor containing at least one Si--N bond, catalytically cleaving an Si--N bond in the precursor in the presence of a transition metal catalyst effective to activate Si--N bonds, such cleavage being carried out in the presence of hydrogen or a hydrogen donor, and reacting the cleavage product to produce an initial polysilazane product; or (b) providing one or more reactants which contain an Si--H bond and an N--H bond, and causing reaction to occur between such Si--H and N--H bonds in the presence of a transition metal catalyst effective to activate Si--H and N--H bonds, to produce an initial polysilazane product having at least two Si--N bonds.

Claim 9

A method of preparing silazanes and siloxazanes suitable as preceramic polymers, comprising the steps of: (a) providing a linear, branched or cyclic starting material having the structure --R' 2 Si--A-- in its molecule, in which A is hydrogen, NR, or Si and wherein said starting material is oligomeric, polymeric or copolymeric; (b) providing a transition metal catalyst effective to activate Si--N, Si--Si and/or Si--H bonds; and (c) reacting the starting material in the presence of such catalyst with (1) hydrogen or a hydrogen donor where A is NR and the starting material is part of a silazane or (2) H--X--R where A is hydrogen or Si, wherein: the R groups are independently selected from the group consisting of: hydrogen; boryl; hydrocarbyl including lower alkyl, alkenyl, alkynyl, aryl, lower alkyl substituted aryl, cycloaliphatic; silyl or polysilyl; said hydrocarbyl or silyl optionally substituted with amino, hydroxyl, an ether moiety or an ester moiety, lower alkoxy, a fused aromatic radical of 8 to 20 carbon atoms, or an organometallic radical; the R' moieties are independently selected from the group consisting of: hydrogen; amino; hydrocarbyl including lower alkyl, alkoxy, alkenyl, alkynyl, aryl, lower alkyl substituted aryl, cycloaliphatic; silyl or polysilyl; said hydrocarbyl or silyl optionally substituted with amino, hydroxyl, an ether moiety or an ester moiety, lower alkoxy, or a fused aromatic radical of 8 to 20 carbon atoms, and wherein R and R' may be part of an oligomeric or polymeric structure; and X is selected from the group consisting of NR, NR--NR, and NR--R--NR.

Claim 10

A method of preparing silazanes and siloxazanes suitable as preceramic polymers, comprising the steps of: (a) providing a linear, branched or cyclic starting material having the structure --R' 2 Si--A-- in its molecule, in which A is hydrogen, NR, or Si and wherein said starting material is oligomeric, polymeric or copolymeric; (b) providing a transition metal catalyst effective to activate Si--N, Si--Si and/or Si--H bonds; and (c) reacting the starting material in the presence of such catalyst with (1) hydrogen or a hydrogen donor where A is NR and the starting material is part of a silazane or (2) H--X--R where A is hydrogen or Si, wherein: the R groups are independently selected from the group consisting of: hydrogen; boryl; hydrocarbyl including lower alkyl, alkenyl, alkynyl, aryl, lower alkyl substituted aryl, cycloaliphatic; silyl or polysilyl; said hydrocarbyl or silyl optionally substituted with amino, hydroxyl, an ether moiety or an ester moiety, lower alkoxy, a fused aromatic radical of 8 to 20 carbon atoms, or an organometallic radical; the R' moieties are independently selected from the group consisting of: hydrogen; amino; hydrocarbyl including lower alkyl, alkoxy, alkenyl, alkynyl, aryl, lower alkyl substituted aryl, cycloaliphatic; silyl or polysilyl; said hydrocarbyl or silyl optionally substituted with amino, hydroxyl, an ether moiety or an ester moiety, lower alkoxy, or a fused aromatic radical of 8 to 20 carbon atoms, and wherein R and R' may be part of an oligomeric or polymeric structure; and X is selected from the group consisting of NR, NR--NR, and NR--R--NR.