| 摘要 |
Prodn. of siloxane polymers comprises contacting a fluid comprising a siloxane polymer precursor(s) selected from cyclic siloxanes (I) and linear siloxanes (II), with an effective amt. of a heteropoly catalyst having a Keggin structure, selected from heteropoly acids (III) and their salts and mixed acid-salts, at a temp. between 23[deg]C and the b.pt. of the siloxane polymer precursor, wherein ( RR'SiO)a(I), (II) and HnXM12O40 (III) are respectively of formulae (1), (2) and (3). R = (substd.) monovalent 1-6C hydrocarbon; R' = H or (substd.) monovalent 1-6C hydrocarbon; a = 3 or more; b = 1 or more; X = B+3, Si+4, Ge+4 or P+5; M = Mo+6 or W+6; and n = 3, 4 or 5 as required for the valence of the heteropolyacid to equal 0. |
