Synthesis of linear polysiloxanes with electron-donating organophosphorus pendant groups by kinetically controlled ring-opening polymerization

Six-membered ring siloxane monomers containing a phosphorus electron-donating groupR=–CH₂CH₂PPh₂ (1), –CH₂CH₂P(S)Ph₂ (2), and –CH₂CH₂P(O)Ph₂ (3) were synthesized. The anionic ring-opening polymerization of these monomers with kinetic control of products has been studied using tetrahydrofuran (THF) as solvent and lithium silanolates as initiators. The polymerization leads to a high molecular weight linear polymer with a very good yield in the case of2 and with a fairly good yield in the case of1 and3. The presence of the phosphorus group enhances the cyclization and broadens the molecular weight distribution of the linear polymer. This effect is relatively weak for the thiophosphinoyl group. At least in the case of the polymer obtained from2, phosphorus groups are distributed uniformly in the macromolecule, however, their arrangement along the chain is not regular. The interaction of polymers obtained from monomers1, 2, and3 with some electrophiles such as alkyl or silyl halides was demonstrated to lead to generation of polyelectrolytes.