Polymer-based fibrous hybrid membranes by in situ synthesis of inorganic nanoparticles

We present an innovative method to fabricate hybrid polymer/inorganic nanoparticles (NPs) fibrous membranes. In particular, the proposed method is based on a solvent-free two-step process. The first step deals with the electrospinning of a polymer/NPs precursor solution, while in the second step the in situ synthesis of NPs takes place, by mean of a thermally-induced solid-state reaction. Such method (schem in Figure 1) allows to obtain fibres homogeneously decorated with NPs, overcoming the typical particles aggregation that affects nanocomposites prepared by conventional mixing methods. In addition, the in situ formation permits to have exposed NPs on the fibres surface, which combined with high surface area offered by the fibrous structure result in a multifunctional material. Herein, two examples of hybrid nanocomposite membranes obtained by this approach are reported. PMMA membranes modified with ZnO NPs have shown reversible UV-switchable wettability and permeability, improved thermal stability and antibacterial activity, which can be controlled simply varying the filler content.[1] On the other hand, PVDF/CeO2/Au fibrous nanocomposites have shown photocatalytic degradation activity induced by visible light, thanks to the modification with Au NPs, which results in a narrowing effect of the CeO2 bandgap. The Au NPs also increase the Ce+3/Ce+4 ratio that greatly enhances the radical scavenging activity of CeO2.[2] In conclusion, the versatility of the presented multifunctional membranes as well as the light-weight and flexibility offered by the polymeric fibres, make these materials valuable alternatives to the nowadays existing systems based on NPs supported on ceramic materials. Furthermore, the present findings demonstrate that the proposed fabrication method is a promising and straightforward approach to obtain polymer-based hybrid membranes for several applications such as filtration, wound management and water purification, among others. [1] Morselli D. et al., Thermally-induced in situ growth of ZnO nanoparticles in polymeric fibrous membranes, Composites Science and Technology 149 (2017) 11-19 [2] Morselli D. et al., Ceria/gold nanoparticles in situ synthesized on polymeric membranes with enhanced photocatalytic and radical scavenging activity, accepted on ACS Applied Nano Materials (2018)