Zeng Wenhui, Buckner Steven W, Jelliss Paul A
Department of Chemistry, Saint Louis University, 3501 Laclede Avenue, Saint Louis, Missouri 63103, United States.
ACS Omega. 2017 May 11;2(5):2034-2040. doi: 10.1021/acsomega.7b00145. eCollection 2017 May 31.
We present an investigation of the photochemistry of aluminum nanoparticles (Al NPs) capped with poly(methyl methacrylate) (PMMA). Powder X-ray diffraction and Fourier transform infrared spectroscopy with total attenuated reflection confirm the presence of crystalline aluminum cores and the PMMA cap and allow us to confirm the latter's photodegradation upon exposure to UV light. The PMMA-Al NPs were also characterized by differential scanning calorimetry coupled with thermogravimetric analysis to study the thermal profiles for polymer combustion and metal oxidation exotherms. Transmission electron microscopy confirms that the Al NPs, around 36 nm in diameter, are embedded in the PMMA matrix. Following UV irradiation, the PMMA-Al NPs react considerably faster with alkaline solutions, compared with unphotolyzed samples. Photoactivation of the nanocomposite induces partial decomposition of the PMMA capping layer, exposing the underlying reactive metal cores to the surrounding environment and accelerating its redox reactivity. Photolysis times of 1, 6, 24, and 52 h were investigated to establish a minimum UV exposure time for the activation of the PMMA-Al NPs toward hydrolytic hydrogen gas generation.
我们展示了对聚甲基丙烯酸甲酯（PMMA）包覆的铝纳米颗粒（Al NPs）光化学性质的研究。粉末X射线衍射和全衰减反射傅里叶变换红外光谱证实了结晶铝核和PMMA包覆层的存在，并使我们能够确认后者在紫外光照射下的光降解。还通过差示扫描量热法结合热重分析对PMMA-Al NPs进行了表征，以研究聚合物燃烧和金属氧化放热的热曲线。透射电子显微镜证实，直径约36 nm的Al NPs嵌入在PMMA基质中。与未光解的样品相比，紫外照射后，PMMA-Al NPs与碱性溶液的反应速度明显加快。纳米复合材料的光活化导致PMMA包覆层部分分解，使下面的活性金属核暴露于周围环境中，并加速其氧化还原反应活性。研究了1、6、24和52小时的光解时间，以确定使PMMA-Al NPs对水解制氢产生活化作用所需的最短紫外照射时间。
