Study of Microemulsion Polymerization Conditions on the Preparation of 'Stimuli' Responsive Copolymer Nanogels of N‐Acryloyl‐N′‐Methyl Piperazine and Methyl Methacrylate

pH responsive copolymer nanogel particles of N‐acryloyl‐N′‐methyl piperazine (AcrNMP) and methyl methacrylate (MMA) were prepared by a suitable oil‐in‐water type microemulsion polymerization. Effect of microemulsion polymerization conditions such as water content, surfactant‐to‐monomer ratio, amount of monomer, and crosslinker content were studied. The nanogel particles showed spherical morphology with narrow size distribution. The nanogels swelled excessively in acidic solutions reaching a diameter of 750 nm and de‐swelled to 350 nm in basic solutions. This pH response to swelling is due to the protonation of N′‐methyl piperazine nitrogen that leads to electrostatic interactions within the nanogel.