10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Polymer Coating of Inorganic Semiconductor Nanoparticles by Aerosol Approach
Masoom Shaban, Jalal Poostforooshan, ALFRED P. WEBER, TU Clausthal
Abstract Number: 696 Working Group: Materials Synthesis
Abstract Polymer coated inorganic semiconductor nanoparticles (ISNs) have attracted great attention due to enormous applications such as biomedical, catalysis, electronics, etc. Generally, the ISNs−polymer nanohybrids have been synthesized in the liquid phase methods which an appropriate solvent and surfactants are always required and they include several time-consuming steps. Moreover, in order to improve the compatibility between ISNs and monomers, suitable surface modification of inorganic nanoparticles is usually necessary.
To overcome the drawbacks of conventional wet methods, the work presented here describes a novel and facile approach to produce various ISNs−polymer core-shell including ZnO, TiO2, and Fe3O4 nanoparticles by a surfactant-free aerosol-based synthesis [1]. In this regard, fresh spherical ZnO nanoparticles were initially generated by spark discharge followed by the sintering furnace in the gas phase. The size distributions of the spark generated ZnO nanoparticles sintered at different temperatures were measured using a scanning mobility particle sizer (SMPS).
The resulting ZnO nanoparticles exhibit excellent performance in the photocatalytic surface-initiated polymerization of butyl acrylate monomer in the continuous aerosol–photopolymerization, within the average aerosol residence time of 35 s in the photoreactor. This method is based on heterogeneous condensation of monomer vapor around the surface of gas-born ISNs, which is then polymerized ‘‘in flight’’ under UV light irradiation. In this one-pot synthesis, ISNs act not only as inorganic cores, but also at the same time are able to release charge carriers (electron-hole pairs) upon photoexcitation which drive the free radical polymerization near their surface. Therefore, no added initiator is required. To further investigate the basis and the mechanism of our experimental results, the optical properties of ZnO nanoparticles during the UV irradiation in the gas phase process was simulated by a three-dimensional finite difference time-domain (FDTD) method. Moreover, the coating efficiency was evaluated by aerosol photoemission and the results demonstrate that monomer and polymer coating efficiency are 99% and 80%, respectively.
Then, to verify the generality of this method toward coating different kinds of ISNs, rod-like ZnO, TiO2 P25, and magnetic Fe3O4 nanoparticles were used as inorganic cores and photoinitiators. Interestingly, the thickness of polymer shell can be easily adjusted at the desired nanoscale by tuning the monomer vapor pressure. The molecular structure of the core-shell nanoparticles was characterized using 1H NMR, FTIR, XRD and UV−vis spectroscopy. The polymer shell was also confirmed by TEM and XPS methods.
Finally, to investigate the potential applications of the nanohybrids in the fabrication of novel composites, the successful change in the surface hydrophobicity of ISNs after the encapsulation with the polymer shell was confirmed by their preference for an organic solvent.
[1] M. Shaban, J. Poostforooshan, and A. P. Weber, J. Mater. Chem. A, 2017, 5, 18651–18663.