Fig. 1: Chemical structure and systematic design space of hydrophobic comonomers.

A The nanogels are comprised of (1) a hydrophilic, cationic monomer 2-(diethylamino) ethyl methacrylate (DEAEMA) that imparts the pH-response by ionization of amine pendant groups; (2) a tetraethylene glycol dimethacrylate (TEGDMA) crosslinker to improve CA retention; and (3) surface-grafted poly (ethylene glycol) methacrylate (PEGMA) to impart serum stability. Nanogels are synthesized using a UV-initiated oil-in-water emulsion polymerization using Brij30 and MyTAB as emulsion stabilizers and Irgacure 2959 as the initiator. B Hydrophobic n-alkyl methacrylate monomers incorporated into the co-polymer network with systematic variation in chain length (methyl, ethyl, butyl, hexyl, and 2-ethylhexyl methacrylate) and in steric bulk (ethyl, isopropyl, tert-butyl, phenyl, cyclohexyl, and benzyl methacrylate).