Nitroxide-mediated surfactant-free emulsion copolymerization of methyl methacrylate and styrene using poly(2-(diethyl)aminoethyl methacrylate-co-styrene) as a stimuli-responsive macroalkoxyamine
The SG1-mediated copolymerization of 2-(diethyl)aminoethyl methacrylate (DEAEMA) and a small percentage of styrene (S) was performed with different initiating systems including a monocomponent initiating system using an alkoxyamine of n-hydroxysuccinimidyl BlocBuilder (NHS-BlocBuilder) at 80 °C and a bicomponent initiating system using 2,2′-azobis[2-(2-imidazolin-2-yl)propane] (VA-061) as the initiator and N-tertbutyl-N-(1-diethylphosphono-2,2-dimethylpropyl)nitroxide (SG1) as the nitroxide at 100 °C. The resultant macroalkoxyamines, poly(DEAEMA-co-S)-SG1, were used as pH-sensitive macroinitiators in the nitroxide-mediated surfactant-free emulsion copolymerization of methyl methacrylate (MMA) and styrene at 90 °C, which proceeded via a polymerization-induced self-assembly (PISA) process, leading to the in situ formation of pH-responsive amphiphilic block copolymers. The reaction was well-controlled with high initiation efficiency and exhibited excellent livingness as evidenced by evolution of the molar mass distribution. The final latex particles were pH-sensitive with excellent colloidal stability and monomodal size distribution.