Polysilazane/polysiloxane block copolymers

A method of making a polysilazane/polysiloxane block copolymer comprising the steps of:

• (i)preparing a polysilazane from a halosilane or mixture of halosilane monomers by polymerizing in the presence of from at least about 5 equivalents of anhydrous liquid ammonia based on the total equivalents of X in the monomer mixture, wherein at least one halosilane monomer is a compound of the general formula:
• 8
• where R is methyl or ethyl, X is chlorine, m is 1 or 2, n is 1 or 2, p is 1 or 2, and m+n+p=4;
• and
• (ii)reacting said polysilazane with about a 25% to a 400% molar amount of the polysiloxane component.

A method of making a polysilazane/polysiloxane block copolymer comprising the steps of:

• (i) preparing a polysilazane from a halosilane or mixture of halosilane monomers by polymerizing in the presence of from about 5 to about 10 equivalents of anhydrous liquid ammonia wherein at least one halosilane monomer is a compound of the general formula:
• 9
• where R is methyl or ethyl, X is chlorine, and m is 1 or 2, n is 1 or 2, p is 1 or 2, and m+n+p=4;
• and
• (ii) reacting said polysilazane with about a 25% to a 400% molar amount of polysiloxane at a temperature of about 25° to about 200° C., wherein said polysiloxane comprises structural units selected the group consisting of:
• 10
• wherein R is independently selected from hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted and unsubstituted alkenyl or substituted or unsubstituted aryl.