Synthesis and characterization of α,ω‐bis(4‐hydroxybutyl) polydimethylsiloxanes

Abstract α,ω‐Bis(4‐hydroxybutyl) polydimethylsiloxane (molecular weight 1500 to 4500) can be pre‐pared with well‐controlled molecular weight through the reaction of 1,3‐bis(4‐hydroxybu‐tyl)tetramethyl disiloxane and dimethoxydimethyl silane or diethoxydimethyl silane in the presence of a stoichiometric amount of water and hydrochloric acid. The molecular weight of these hydroxybutyl‐terminated polysiloxanes can be determined fairly consistently by a titration method. These polysiloxanes are stable toward cyclization.