Chemistry of a series of aluminum-modified polysilazanes: Synthesis, pyrolysis behaviour and microstructural evolution

Abstract

A series of polyaluminosilazanes was synthesized by reaction of dimethylethylamine alane complex with polysilazanes. Starting from different dichlorosilanes, polysilazanes were obtained by means of ammonolysis. The latter reacted with the alane complex and led to solid polyaluminosilazanes that can be described as "custom-made" polymers since all the steps were monitored and controlled (from the choice of the molecular precursor to the polymerization and the functionalization with aluminum) in order to study the effect of the introduction of Al on the different reactive sites of the Si-backbone in the polysilazanes. Detailed information on the polymers structures were obtained by FTIR and multinuclear solid state NMR spectroscopies. The transition from the polymeric state to the ceramic inorganic state was investigated by means of solid-state NMR spectroscopy and finally the

Investigation of polymer-derived Si–(B)–C–N ceramic/reduced graphene oxide composite systems as active catalysts towards the hydrogen evolution reaction

“…Polymer-Derived Ceramics (PDCs) are a class of ceramics synthesized by the thermal decomposition of polymeric precursors that are best known for their excellent high-temperature stability, their remarkable thermo-mechanical properties and their chemical stability; attributed to their unique composition and microstructures 20 , 21 . Moreover, the final properties of PDCs can be modified in a controlled manner by tailoring the precursor’s composition and the processing parameters.…”

“…The first generation of PDCs was the SiC fibers developed by Yajima in 1975 for high-temperature applications 22 . Since then, many other ternary and quaternary carbides and nitrides have been extensively investigated such as silicon oxycarbide (SiOC) 23 , boron modified silicon carbide (SiBC) 24,25 , silicon carbonitride (SiCN) 26 , boron and aluminum modified silicon carbonitride (SiBCN [27][28][29] , SiAlCN 21,30 ). PDCs display semi-conducting behavior allowing them to be used in Micro-Electro-Mechanical Systems (MEMS) 31 , p-n junction devices 32 , micro glow plugs 33 and pressure sensors 34 .…”

Preparation of hybrid cyanate ester resin in the presence of polysilazane and its properties

“…Polydimethylsilazane (PMS) and polymethylsilazane (PHS) were synthesized via the ammonolysis of dichlorodimethylsilane and dichloromethylsilane, respectively. 29 –31 PMS and PHS were obtained as colorless liquids, their structures were shown in Figure 2. The FT-IR spectra are shown in Figure 3(a) and (b): ν (cm –1 ) = 3400 and 1174 (N–H), 2958 and 2900 (–CH 3 ), 2129 (Si–H), 810–990 (Si–N).…”

Design and Manufacturing of Si-Based Non-Oxide Cellular Ceramic Structures through Indirect 3D Printing

“…Preceramic polymers are a class of precursors that transform into ceramics upon pyrolysis at high temperature under inert or reactive atmosphere [12]. In the last years, Polymer-Derived Ceramics (PDCs)including SiCN and SiC-have been attracting a lot of attention as high strength materials for several applications under harsh environments due to their unique multiphase structure, tailorable chemical composition, high thermal and chemical stability, excellent corrosion and oxidation resistance and designable shape [13][14][15][16][17][18]. Material extrusion, one of the most affordable 3D printing technologies, allows objects to be created by extruding the materials through a heated nozzle to build up a layer that instantly hardens so that the next layer adheres on top in a repeated process, ultimately leading to the formation of a 3D object.…”