Schmarsow Ruth N, dell'Erba Ignacio E, Villaola Micaela S, Hoppe Cristina E, Zucchi Ileana A, Schroeder Walter F
Institute of Materials Science and Technology (INTEMA), University of Mar del Plata and National Research Council (CONICET), Juan B. Justo 4302, 7600 Mar del Plata, Argentina.
Langmuir. 2020 Nov 24;36(46):13759-13768. doi: 10.1021/acs.langmuir.0c01916. Epub 2020 Nov 11.
Metal/polymer nanocomposites have attracted much attention in recent years due to their exceptional properties and wide range of potential applications. A key challenge to obtain these materials is to stabilize the metal nanoparticles in the matrix, avoiding uncontrolled aggregation processes driven by the high surface free energy of nanosized particles. Here, we investigate the aggregation mechanism of primary particles in gold-epoxy nanocomposites prepared via light-assisted in situ synthesis, under different irradiation conditions. The growth and aggregation of gold nanoparticles were monitored in situ by time-resolved small-angle X-ray scattering experiments, whereas spectroscopic measurements were performed to interpret how matrix polymerization influences the aggregation process. It was found that light intensity has a greater influence on the reduction rate than on the polymerization rate. Under irradiation, gold nanostructures evolve through five time-defined stages: nuclei-mass fractals-surface fractals-spherical nanoparticles-aggregates. If the maximum in the polymerization rate is reached before the aggregation step, individual primary nanoparticles will be preserved in the polymer matrix due to diffusional constraints imposed by the reaction medium. Because the light intensity has a different influence on the reduction rate than on the polymerization rate, this parameter can be used as a versatile tool to avoid aggregation of gold nanoparticles into the polymer matrix.
近年来，金属/聚合物纳米复合材料因其优异的性能和广泛的潜在应用而备受关注。获得这些材料的一个关键挑战是在基体中稳定金属纳米颗粒，避免由纳米颗粒高表面自由能驱动的不受控制的聚集过程。在此，我们研究了在不同辐照条件下，通过光辅助原位合成制备的金-环氧树脂纳米复合材料中初级颗粒的聚集机制。通过时间分辨小角X射线散射实验对金纳米颗粒的生长和聚集进行原位监测，同时进行光谱测量以解释基体聚合如何影响聚集过程。结果发现，光强度对还原速率的影响大于对聚合速率的影响。在辐照下，金纳米结构经历五个时间定义的阶段：核-质量分形-表面分形-球形纳米颗粒-聚集体。如果在聚集步骤之前达到聚合速率的最大值，由于反应介质施加的扩散限制，单个初级纳米颗粒将保留在聚合物基体中。由于光强度对还原速率和聚合速率的影响不同，该参数可作为一种通用工具，避免金纳米颗粒在聚合物基体中聚集。
