A Thermodynamic Roadmap for the Grafting-through Polymerization of PDMS 11 MA.

Grafting-through atom transfer radical polymerization (ATRP) was used to polymerize a sterically hindered poly(dimethylsiloxane) methacrylate (PDMS 11 MA, M n = 1000) macromonomer to high conversion as a function of temperature, solvent, initial monomer concentration, and pressure. Higher polymerization yields were obtained when polymerizations were conducted at (i) lower temperature ( T ), (ii) in a poor solvent for the side chain, (iii) higher initial monomer concentration ([M] 0 ), and (iv) higher pressure by mitigating the contribution of the equilibrium monomer concentration ([M] eq ). The enthalpy of polymerization (Δ H p ) and entropy of polymerization (Δ S p ) were more negative in poor solvents. Polymerizations at ambient pressure required higher [M] 0 , use of a poor solvent, and lower temperatures to reach higher conversion with good control, whereas high pressure ATRP (HP-ATRP) displayed better control under dilute conditions. Grafting-through polymerization at high P and higher [M] 0 was less controlled, plausibly due to limited solubility and mobility of the copper catalyst in the highly viscous medium.