CLuster-based Infrared selectivity MATerials for Energy saving applications – CLIMATE

CLIMATE aims at preparing new composite coating materials for glass solar control as well as straightforward processes for their surface coating. The originality of CLIMATE lies in the use of functional cluster-based composite materials as glass coater. The M6@silice-PDMS composite (PDMS = polydimethylsiloxane) will be made by embedding inorganic octahedral clusters (M6 = Nb6, Ta6 for mononuclear clusters, heteronuclear clusters M6 = Nb or Ta associated with 3d or 4d metal atoms) into hybrid silica-PDMS matrix using a sol gel process. The metal atom clusters will be associated with halogen or with both halogen and oxygen. They will combine UV absorption, NIR blocking properties as well as inorganic dye with color ranging from green, green blue to brown-grey colors. The new composites will answer the criteria of Saint Gobain (SG) with dual benefits of (i) optimization of daylighting & energy savings and (ii) aesthetics. Indeed, energy efficient smart glass or plastic transparent materials aims at reducing the energy consumption for houses, cars and greenhouses, leading to a better thermal insulation by controlling near-infrared (NIR) and UV solar radiation without reducing the standard of living. Thus, NIR/UV reflective or absorptive coating materials should be ideally transparent in the visible and only block transmission of NIR/UV light from solar radiation or heat transfer for evident great interest in worldwide challenge of reducing energy consumption. Currently, commercially-available active layers are mainly deposited by vacuum processes, which are expensive. The research in active layered materials suitable for solution route is of great interest for SG. These layers consist in a matrix (organic, inorganic or hybrid) in which are introduced several actives species with NIR and/or UV absorption properties. However, in order to reach good solar control capabilities, large amounts of active particles within the matrix are introduced up to now. Such large amounts induce alterations of mandatory properties for industrial applications. Moreover, the chemistry of each nanoparticle can be very different making trickier the embedding processing. The originality in the use of M6 cluster lies in the flexibility of compositions (metals and ligands) and metal oxidation states that enable to tailor-made functional building blocks with optimized color, UV absorption and NIR blocking properties. Moreover, the nanosized metal clusters reduce drastically the scattering of visible light and increase the transparency that are faced using larger nanoparticles. To reach optimum optical properties, it could be necessary to embed several kind of M6 clusters within the same matrix possessing different optical properties. Note that their chemical behavior will be very similar. Consequently, it will favor straightforward one pot embedding processes. CLIMATE is a PRCE project gathering 3 partners: Institut des Sciences Chimiques de Rennes-UMR 6226 (P1), the Laboratory for Innovative Key Materials and Structure LINK-UMI 3629-SG-CNRS-NIMS (P2) and SG Research Center – Aubervilliers (P3) which is an industrial research and development center working for the subsidiaries of the SG Group. The methodology of this project has been thought in order to minimize the risks thanks to complementarities of partners. As PRCE proposal, SG will beneficiate from the expertise of P1 in chemistry and theoretical rationalizations of clusters and that of P2, specialized in integration and characterization of cluster based thin film nanocomposites. P1 and P2 will beneficiate from the expertise of industrials partner P3 in the optimization of large coating of glass surfaces as well as in technology transfer to industrial scale. CLIMATE is at the frontier between materials development and the underlying material science. It will produce both new fundamental knowledge on composite materials and their processing as well as potential patentable results.