Preparation and properties of dimethyl phosphonomethyl methylsiloxane dimethylsiloxane copolymers

Abstract

AbstractDimethyl phosphonomethylheptamethylcyclotetrasiloxane (II) and 1, 3‐bis(dimethyl phosphonomethyl)tetramethyldisiloxane (III) have been prepared by Arbuzov reaction of trimethyl phosphite with bromomethylheptamethylcyclotetrasiloxane (I) and 1, 3‐bis(bromomethyl)tetramethyldisiloxane, respectively. Dimethyl phosphonomethylmethylsiloxane dimethylsiloxane copolymers have been prepared by acid‐catalyzed ring‐opening polymerization of II with hexamethyldisiloxane (MM) as an end‐capping reagent and by reaction of II with III as an end‐capping reagent. Dimethylsiloxane polymers with dimethyl phosphonomethyldimethylsiloxy end groups have been prepared by acid‐catalyzed polymerization of octamethylcyclotetrasiloxane (D4) and III. Under these conditions hydrolysis of the dimethyl phosphonate ester groups was a problem. On the other hand Arbuzov reaction of trimethyl phosphite with bromomethylmethylsiloxane dimethylsiloxane copolymer gave a dimethyl phosphonomethylmethylsiloxane dimethylsiloxane copolymer with uniform properties. These polymers have been characterized by 1H‐, 13C‐, 29Si‐, and 31P‐NMR spectroscopy. Their molecular weight distributions have been determined by gel permeation chromatography (GPC) and their thermal stability measured by TGA.