ABSTRACT High-performance ceramics play a key role in the development of materials destined to high temperature structural applications. Such materials can be prepared by thermally-induced conversion of processible preceramic polymers. The main advantage of this Polymer-Derived Ceramic (PDC) approach lies in the feasibility of producing shaped bodies such as fibres. The aims of our works were to synthesize molecular precursors whose the thermolysis leads to polymers with specific properties for the preparation of ceramic fibres. In particular, our research is focused on the elaboration of hexagonal boron nitride (h-BN) fibres from tailored borazine-based polymers, since the cyclic B3N3 borazine core can be seen as the basal unit of h-BN. Hence, polymers derived from tri-(alkylamino)borazines and tri-(borylamino)borazines were studied in order to evaluate the influence of the kind of inter-ring linkages on their melt-spinnability and on the mechanical and structural properties of the resulting BN fibres. These works confirmed the close relationship between the melt-spinnability of the preceramic polymer and the nature of the pendent substituents linked to the polyborazine backbone and consequently to the starting molecular precursor structure. As the main result of this systematic study, this mini-review will exemplify that the preparation of polymers with specific inter-ring bridged bonds allow the achievement of excellent candidates for melt-spinning and thermally-induced conversion processes which lead subsequently to BN fibres with high mechanical properties
Buy this Article
|