Safer by design approaches for TiO₂ based photocatalytic paints.

Our investigation focused on the efficacy of new nano-TiO₂ catalysts in consuming indoor volatile organic compounds (VOCs) when integrated into inorganic paint binders. A photocatalytic stability of the inorganic paint binders has also been studied.

The study described in this paper was conducted in the framework of the European nPSize project (EMPIR program) with the main objective of proposing new reference certified nanomaterials for the market in order to improve the reliability and traceability of nanoparticle size measurements. For this purpose, bimodal populations as well as complexly shaped nanoparticles (bipyramids, cubes, and rods) were synthesized. An inter-laboratory comparison was organized for comparing the size measurements of the selected nanoparticle samples performed with electron microscopy (TEM, SEM, and TSEM), scanning probe microscopy (AFM), or small-angle X-ray scattering (SAXS). The results demonstrate good consistency of the measured size by the different techniques in cases where special care was taken for sample preparation, instrument calibration, and the clear definition of the measurand. For each characterization method, the calibration process is described and a semi-quantitative table grouping the main error sources is proposed for estimating the uncertainties associated with the measurements. Regarding microscopy-based techniques applied to complexly shaped nanoparticles, data dispersion can be observed when the size measurements are affected by the orientation of the nanoparticles on the substrate. For the most complex materials, hybrid approaches combining several complementary techniques were tested, with the outcome being that the reliability of the size results was improved.

The safe and sustainable by design (SSbD) concept integrates functionality with safety and sustainability aspects at an early phase of the innovation and product development process. A qualitative integrated safe, sustainable, and recyclable by design (SSRbD) approach was developed in a series of cocreation workshops involving risk assessors, toxicologists, eco-design, and sustainable development experts. The SSRbD approach consists of (1) identification of functionality, criticality, toxicity, environmental, social, circularity/recyclability, and economic impacts in a life cycle thinking perspective; (2) development of SSRbD strategies; and (3) verification of SSRbD strategies. The first two steps were applied to three case studies (building sector: new recyclable-by-design bio-sourced polyurethane (PU) to replace PVC (polyvinyl chloride) as insulating material for window frames; transport sector: fire-resistant, intrinsically recyclable epoxy-vitrimer materials for sustainable composites to replace metal for train body; and packaging sector: recyclable MultiNanoLayered (MNL) films to replace multilayer films for packaging with drastically reduced concentrations of compatibilizers). Guidance for identifying polymer material-relevant information needs was developed. In terms of internal organization, an interdisciplinary group for case study assessment was developed. Each case study comes with specific challenges and needs, which is why a tailor-made approach is required for the application of SSRbD of polymeric materials and products.