Temperature-responsive smart nanoreactors: poly(N-isopropylacrylamide)-coated Au@mesoporous-SiO2 hollow nanospheres.
A nanoreactor with temperature-responsive poly(N-isopopylacrylamide) (PNIPAM) coated on the external pore mouth of mesoporous silica hollow spheres and Au nanoparticles at the internal pore mouth were fabricated. Such spatial separation allows both Au nanoparticles and PNIPAM to function without interfering with each other. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, and temperature-dependent optical transmittance curves demonstrate successful grafting of PNIPAM. This nanoreactor shows repeated on/off catalytic activity switched by temperature control. It shows excellent catalytic activity toward 4-nitrophenol (4-NP) reduction at 30 °C [below lower critical solution temperature (LCST) of PNIPAM] with a turnover frequency (TOF) of 14.8 h(-1). However, when the temperature was 50 °C (above LCST), the TOF dropped to 2.4 h(-1). Kinetic studies indicated that diffusion into the mesopores of the catalyst was the key factor, and the temperature-responsive behavior of PNIPAM was able to control this diffusion.
Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Zhe
Z
Chen
Zhi-Min
ZM
Cui
Chang-Yan
CY
Cao
Wei-Dong
WD
He
Lei
L
Jiang
Wei-Guo
WG
Song
D000178:Acrylamides / Q000737:chemistry*; D000180:Acrylic Resins; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D054118:Nanospheres / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
D000178:Acrylamides; D000180:Acrylic Resins; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D006046:Gold; D012822:Silicon Dioxide