Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Langmuir. 2012 Sep 18;28(37):13452-8. doi: 10.1021/la3022535. Epub 2012 Sep 6.
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.
一种纳米反应器，其在介孔硅空心球的外孔口上涂覆有温度响应性的聚（N-异丙基丙烯酰胺）（PNIPAM），在内部孔口处有金纳米粒子。这种空间分离允许金纳米粒子和 PNIPAM 彼此独立地发挥作用，而不会相互干扰。透射电子显微镜（TEM）、热重分析（TGA）、傅里叶变换红外（FTIR）光谱和温度依赖的光透过率曲线表明 PNIPAM 的接枝成功。这种纳米反应器通过温度控制实现了重复的开/关催化活性切换。它在 30°C（低于 PNIPAM 的低临界溶液温度（LCST））下对 4-硝基苯酚（4-NP）还原表现出优异的催化活性，转化率频率（TOF）为 14.8 h(-1)。然而，当温度为 50°C（高于 LCST）时，TOF 下降到 2.4 h(-1)。动力学研究表明，催化剂进入介孔的扩散是关键因素，而 PNIPAM 的温度响应行为能够控制这种扩散。
