Photo- and pH-Responsive Hybrid Colloidal Particles

Materials that respond to environmental changes in a predictable manner are called "smart". Here, smart dual-responsive hybrid colloidal particles were prepared using the interface-mediated reversible addition-fragmentation chain-transfer (RAFT) polymerization method. The structure and morphology of the prepared poly(methacrylated-spiropyran) (p(MMASP)) colloids were characterized by FTIR, H-1-NMR and GPC spectroscopies, and SEM. The molecular weight and polydispersity were determined as 7877 g mol(-1) and 1.16, respectively. Heterocyclic ring cleavage of the spiropyran (SP) pendant group enables the pH- and light-responsive behavior with a reversible conversion between the hydrophobic and hydrophilic states. The isomerization from SP to merocyanine (MC) form proceeds in 7 min, while the reverse action takes 9 min. The pronounced photochromic effect and high fatigue resistance make these colloids suitable for smart applications.