Interphase-Engineered Bio-inspired Ceramic Transparent Composites

• Applicant: Professorin Kaline Pagnan Furlan, Ph.D.
• Subject Area: Glass, Ceramics and Derived Composites ; Coating and Surface Technology ; Synthesis and Properties of Functional Materials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 508235687

This project aims at developing bio-inspired nacre-like ceramic composites with functional integrated optical and mechanical properties. The work hypothesis is that the nano-engineered surface modification of platelets (“bricks”) via molecular layer deposition (MLD) will allow to precisely tailor the interphase (“mortar”) thickness, chemical composition and refractive index in an unprecedent way, enabling the fabrication of composites with integrated high toughness and high transparency. The MLD-engineered platelets are then assembled and 3D printed into bulk nacre-like (brick-and-mortar) structures, generating bulk transparent composites. Natural nacre has an interphase thickness of 10 to 50 nm, which is uniformly distributed around the platelets. Such uniformity and lower thickness are hardly reproduced by currently developed techniques. In addition, the interface between platelets and mortar is often produced by deposition or infiltration without any chemical reaction between mortar and platelets, which reduces the interfacial strength. The best "state of the art" results regarding platelet systems are based on the functionalization of platelet surfaces by chemical methods, but such methods cannot yet fully mimic the mortar thickness as in natural nacre. o address this issue, the current project aims to improve the mortar by nano-surface modification of platelets and bottom-up construction of mortar using molecular layer deposition (MLD). The proposed methodology offers the potential to optimize both the optical and the mechanical properties, leading to “tougher glasses”. The main advantage is the controlled and precise definition of interfaces and interphases, achieved by the engineering of the building blocks (platelets) with MLD coatings that are chemically bonded to the platelets (strong interface) with well-defined thickness (10-50 nm), mimicking the features of natural nacre. Such nacre-like composites find applications as gas-barrier films, fire-retardant films, high-conductivity, impact-resistant and structural materials. In addition, MLD-coated particles can be used for catalysis, pharmaceuticals, pigments, tissue engineering, and in energy storage. Here we focus on optical applications, targeting high transparency and low haze factor. The materials here developed could be an alternative to replace traditional smartphone screens, which are mainly brittle and prone to catastrophic failure.

• DFG Programme: Research Grants
• Major Instrumentation: Spectroscopic ellipsometer
• Instrumentation Group: 5360 Meßgeräte für gestreutes und reflektiertes Licht, optische Oberflächen-Prüfgeräte