Water-swollen nanoparticles are widely used in the medical and cosmetic industries due to their unique properties, such as controlled cargo release. Hydrogel nanoparticles are commonly generated using emulsions to create uniform spherical particles in the dispersed phase. However, these methods often involve the use of toxic solvents and produce significant waste during separation and purification. Additionally, time-intensive separation techniques, such as liquid-liquid extraction can slow down the particle formation process. This presentation will present our study which leverages green chemistry approaches to improve hydrogel nanoparticle synthesis and purification by using a crystallizable inverse nanoemulsion. By using non-toxic oils with a low melting point such as myristic acid, we effectively employed solid-liquid separation to isolate nanoparticles in the aqueous phase post synthesis. Poly(ethylene glycol) diacrylate (PEG-DA) was selected to create hydrogel nanoparticles via thermally induced radical polymerization and redox polymerization. Inverse nanoemulsions with two molecular weights of PEG-DA (Mn = 8000 and Mn = 575), along with two different stirring speeds, were initially tested to evaluate particle size, and recovery. Scanning electron microscopy revealed average particle sizes of 195.80 ± 99.95 nm for PEG-DA 8000 at 100 rpm and 208.7 ± 144.11 nm for PEG-DA 575. To improve sustainability, the oil phase was reused in the process thereby reducing the overall material use while yielding similarly sized nanoparticles. The process's sustainability was assessed using the process mass intensity for the individual recycling steps, which was calculated to be 163.16 ± 43.65. By extending the recrystallization strategy to nanoparticle synthesis, this approach demonstrates significant improvements in sustainability compared to conventional methods.
