Mechanism of sustainable photocatalysis based on doped-titanium dioxide nanoparticles for UV to visible light induced PET-RAFT photo-polymerization
Heterogeneous catalysis is an essential aspect for actual industrialization of chemical processes. Here a TiO2-based powder, typically used in photocatalysis, is exploited for the first time for visible-light-regulated Photoinduced Electron/Energy (PET)-reversible addition–fragmentation chain-transfer (RAFT). Titania is a non-toxic, low-cost, and heterogeneous catalyst that can offer several advantages in terms of sustainable polymerization and photocatalyst (PC) recovery. In this work, we aim not only at unraveling the mechanism of photopolymerization and the important interactions involved, but also at red-shifting the absorption region to achieve vis-light polymerization. The combination of the experimental investigation with Density Functional Theory (DFT) calculations provides new insights into the interactions between the chain transfer agents (CTAs) and the TiO2 surface, unveiling their pivotal role on the reaction rate and polymerization control. Moreover, to shift the polymerization under the less energetic blue light, high-surface area N-doped TiO2 nanoparticles are employed, avoiding the CTA degradation often observed with UV irradiation and increasing the overall sustainability of the process.