Polycarbosilane-Grafted Nanoparticles: Free-Flowing Hairy Nanoparticle Liquids That Convert to Ceramic

摘要

Here, we report a new class of hybrid nanoparticles (NPs) that are self-supporting and display viscous flow behavior in the absence of solvent, yet convert to a purely inorganic material on heating. Hairy nanoparticles (HNPs) composed of silica nanoparticle cores (10-20 nm diameter) and preceramic poly(1,1-dimethylpropylsilane) (I-PCS) brushes were synthesized via a grafting-from approach utilizing hydrosilylation chemistry. The I-PCS polymer brush was grown from the nanoparticle core by anchoring the Pt(0) Karstedt's catalyst to Si-H groups functionalized on the silica surface. The resulting I-PCS-based HNPs were easily dispersed in a variety of organic solvents, displaying Newtonian rheological behavior at low weight percent solvent loadings, while neat HNPs displayed relatively low viscosities. The Krieger-Dougherty equation was used to evaluate viscosity trends as related to corona size, with the corona size being determined through dynamic light scattering. Thermally cured HNPs were successfully converted to SiO2/SiC nanocomposites, as evidenced by X-ray diffraction and attenuated total reflection (ATR)-Fourier transform infrared (FTIR). These unique preceramic HNPs hold considerable promise as a route to high-temperature materials, offering enhanced processability and compositional tailorability compared to neat resins.