The 3D freeze printing (3DFP) of nanocellulose aerogels are demonstrated with large‐scale aligned pore orientations as a sustainable alternative to current acoustical materials. In contrast with the unidirectional pore network orientations obtained from current 3DFP techniques, a bidirectional orientation is achieved by using an inhomogeneous printing substrate to alter the thermal gradient within the print volume. The microstructural morphology shows that bidirectional printing results in a 2D pore orientation, with comparatively thinner pore walls and larger pore widths. Acoustic measurements reveal that altering the pore network characteristics significantly affects the acoustical behavior of the printed CNC aerogels; the wider pores allow the bidirectional CNC aerogels to provide higher sound absorption performance at lower frequencies than the unidirectional samples. Notably, both 3D Freeze printed CNC aerogels provide substantially higher sound transmission loss performance as compared to current acoustical materials. The unidirectional pore structure results in CNC aerogels with higher stiffness and improved energy absorption performance, with both 3D freeze printed CNC aerogels outperforming other CNC aerogel materials in their stiffness‐to‐density ratios. The ability to simultaneously control their pore orientation and macrostructural geometry paves the way for printing complex shaped CNC aerogel structures for multifunctional noise control applications.
Considering the design of structures and materials for use as replacements for biological structures, polymer nanocomposites are desirable materials of construction since they have a large design space, allowing property customization. Biobased nanofibers are particularly suited for these applications since they have high specific mechanical properties and cytocompatibility. Motivated by these attributes, this work examines nanocomposite aerogels and an aerogel/hydrogel hybrid structure designed to mimic an intervertebral disc (IVD), with the aerogel and hydrogel serving as analogs for the annulus fibrosus and the nucleus pulposus, respectively. The aerogels and aerogel/hydrogel hybrid structure contain a mixture of biobased nanofibers, cellulose nanocrystals (CNCs) and chitin nanofibers (ChNFs), and a polyvinyl alcohol (PVA) matrix. Characterization of the structure and properties shows that the nanocomposite aerogels containing CNC/ChNF mixtures have larger pores and decreased mechanical properties as compared to aerogels containing only CNCs or only ChNFs. Building on these results, a hybrid comprised of a CNC/PVA aerogel and a CNC/ChNF/PVA hydrogel is constructed with mechanical properties similar to natural IVDs, providing initial validation of the hybrid concept for IVD replacements and pathways to customization through changing material composition in the aerogel and hydrogel and changing the aerogel and hydrogel fractions in the hybrid structure.
more » « less- PAR ID:
- 10434074
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Applied Polymer Science
- Volume:
- 140
- Issue:
- 33
- ISSN:
- 0021-8995
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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