Fabrication of triple responsive polymer brushes and their catalytic performance after loading palladium†
The uniformly dispersed and structured silica nanoparticles were prepared and functionalized by amino and 2-bromoisobutyrate successively. The random copolymer brushes of 2-(dimethylamino) ethyl methacrylate (DMAEMA) and 1′-(2-acryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) (SPMA) were synthesized from 2-bromoisobutyrate-functionalized silica nanoparticles by surface-initiated atom transfer radical polymerization (SI-ATRP). FT-IR, TGA, XPS, TEM, and EDS verified the successful immobilization of initiator and grafting of the random copolymer. Subsequently, the triple responsive behaviors including thermo-, pH- and photo-sensitivities were investigated using dynamic light scattering (DLS) as well as UV-Vis spectrometry. Furthermore, the active palladium was loaded into the hybrid silica nanoparticles and the catalytic performance was evaluated using a styrene hydrogenation reaction at different temperatures.