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Fabrication of Polyimide Aerogels Cross-Linked by a Cost-Effective Amine-Functionalized Hyperbranched Polysiloxane (NH2–HBPSi)
journal contribution
posted on 2020-08-06, 22:22 authored by Tingting Wu, Jie Dong, Kevin De France, Mengmeng Li, Xin Zhao, Qinghua ZhangPolyimide (PI) aerogels
were prepared from anhydride end-capped
polyamic acid oligomers cross-linked by a low-cost lab-made amine-functionalized
hyperbranched polysiloxane macromer (NH2–HBPSi).
NH2–HBPSi was synthesized via the hydrolysis–condensation
reaction between phenyltrimethoxysilane, tetraethoxysilane, and γ-aminopropylmethyldiethoxysilane,
which are all cheap commercially available silane-coupling agents.
To determine the effects of the NH2–HBPSi cross-linker
on the formation and properties of aerogels, two different PI oligomers,
synthesized from relatively flexible 4,4′-oxidianiline and
rigid-rod 2,2′-dimethylbenzidine, were investigated. The resulting
PI aerogels showed comparable properties with the triamine cross-linked
PI aerogels, such as low densities (0.12 to 0.20 g cm–3), high BET specific surface areas (279 to 460 m2 g–1), low thermal conductivities (29–32 mW m–1 K–1), and excellent mechanical
and thermal properties across the range of NH2–HBPSi
cross-linker concentrations used (2.5 to 12.5 wt %). Moreover, the
thermal insulation, dielectric, and CO2 uptake performances
were also investigated, demonstrating the broad range of potential
applications for these multifunctional cross-linked PI aerogels. Considering
the low-cost and facile synthesis for this NH2–HBPSi
macromer cross-linking agent, we anticipate that this work can overcome
the drawbacks of expensive conventional PI cross-linkers and offer
a simple approach to produce low-cost PI aerogels at scale.