nn0c01888_si_001.pdf (1.24 MB)
Top-Down Approach Making Anisotropic Cellulose Aerogels as Universal Substrates for Multifunctionalization
journal contribution
posted on 2020-05-22, 22:04 authored by Jonas Garemark, Xuan Yang, Xia Sheng, Ocean Cheung, Licheng Sun, Lars A. Berglund, Yuanyuan LiHighly
porous, strong aerogels with anisotropic structural properties
are of great interest for multifunctional materials for applications
including insulators in buildings, filters for oil cleanup, electrical
storage devices, etc. Contemporary aerogels are mostly
extracted from fossil resources and synthesized from bottom-up techniques,
often requiring additional strategies to obtain high anisotropy. In
this work, a universal approach to prepare porous, strong, anisotropic
aerogels is presented through exploiting the natural hierarchical
and anisotropic structure of wood. The preparation comprises nanoscale
removal of lignin, followed by dissolution–regeneration of
nanofibers, leading to enhanced cell wall porosity with nanofibrillated
networks occupying the pore space in the cellular wood structure.
The aerogels retain structural anisotropy of natural wood, exhibit
specific surface areas up to 247 m2/g, and show high compression
strength at 95% porosity. This is a record specific area value for
wood aerogels/foams and even higher than most cellulose-based aerogels
for its assigned strength. The aerogel can serve as a platform for
multifunctional composites including scaffolds for catalysis, gas
separation, or liquid purification due to its porous matrix or as
binder-free electrodes in electronics. To demonstrate the multifunctionality,
the aerogels are successfully decorated with metal nanoparticles (Ag)
and metal oxide nanoparticles (TiO2) by in situ synthesis, coated by the conductive polymer (PEDOT:PSS), and carbonized
to yield conductive aerogels. This approach is found to be a universal
way to prepare highly porous anisotropic aerogels.