Method of making polysiloxanes by ring opening polymerization of dimethylcyclosiloxanes such as hexamethylcyclotrisiloxane (D3) and cyclosiloxanes such as 1,3,5-trimethyl-1,3,5-tris (3',3',3'-trifluoropropyl) cyclotrisiloxane (F3) or 1,3,5,7-tetramethyl-1,3,5,7-tetrakis(3',3',3'-trifluoropropyl) cyclotetrasiloxane (F4) in an acid-free system using electrophillic initiators. The reaction mixture is formed under anhydrous conditions and contains (i) the cyclosiloxanes, (ii) a Lewis base such as 2,6-di-tert-butylpyridine which serves as a co-catalyst and an acid scavenger and, optionally, (iii) a salt of a strong acid such as tetrabutylammonium trifluoromethane sulfonate. The anhydrous mixture is contacted with a silyl ester of a strong acid such as triflic acid. The anhydrous reaction mixture is agitated at room temperature until a polysiloxane is formed. Polymerization can be initiated practically immediately after introduction of the cyclosiloxanes, by first adding the Lewis base to the silyl ester and allowing the Lewis base and the silyl ester to interact.
通过六甲基环三
硅氧烷(D3)等二甲基环
硅氧烷和1,3,5-三甲基-1,3,5-三(3',3'、1,3,5-三甲基-1,3,5-三(3',3',3'-三
氟丙基)环三
硅氧烷(F3)或 1,3,5,7-四甲基-1,3,5,7-四(3',3',3'-三
氟丙基)环四
硅氧烷(F4)。反应混合物是在无
水条件下形成的,其中包含:(i) 环
硅氧烷;(ii) 一种路易斯碱,如
2,6-二叔丁基吡啶,用作辅助催化剂和酸清除剂;(iii) 一种强酸盐,如三
氟甲烷磺酸四丁基
铵。无
水混合物与强酸(如三
氟甲基磺酸)的
硅酯接触。无
水反应混合物在室温下搅拌,直至形成聚
硅氧烷。实际上,在加入环
硅氧烷后,可以立即开始聚合,方法是先将路易斯碱加入
硅烷酯中,让路易斯碱和
硅烷酯相互作用。