| abstract |
A method of preparing silazane polymers, with 3 or more repeating units, of the general formula -((CH3)2N)eSi(R)a(R'HN)fHc(NR')g- and a (CH3)2NH byproduct group where R is hydrogen, an alkyl group having 1-6 carbon atoms or an aryl group having 6-12 carbon atoms, a=0, or 1, b=2-4, C=0-2, d=0 or 1, e=0-2, f=0-2, g=1-3 and a+c+e+f+g=4 for the polymer units; and R' is hydrogen or methyl, whereby the silazane polymer is substantially free of halide impurities, and wherein this method comprises: transaminating an aminosilane of the general formula (R)a((CH3)2N)bHcS; where R is defined as above and a+b+c=4 with an amine of the general formula (CH3)dNH3-d whereby d is defined as above and the amine has a molecular weight lower than 45 all in the presence of an acid catalyst or the ammonium salt of the acid and thereafter condensing to form the polymer. |