More Like this

1. Sustainable Multifunctionality: Bio‐Inspired Printing of Nanocellulose Aerogel Acoustical Materials

   https://doi.org/10.1002/admt.202400232  

   Yang, Guang; Lomte, Amulya; Sharma, Bhisham; Lei, Shuting; Lin, Dong (August 2024, Advanced Materials Technologies)

   Abstract 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. 

   more » « less
2. Orbital-flop transition of superfluid 3He in anisotropic silica aerogel

   https://doi.org/10.1038/s41467-023-44557-5  

   Nguyen, M. D.; Simon, Joshua; Scott, J. W.; Zimmerman, A. M.; Tsai, Y. C.; Halperin, W. P. (December 2024, Nature Communications)

   Abstract Superfluid³He is a paradigm for odd-parity Cooper pairing, ranging from neutron stars to uranium-based superconducting compounds. Recently it has been shown that³He, imbibed in anisotropic silica aerogel with either positive or negative strain, preferentially selects either the chiral A-phase or the time-reversal-symmetric B-phase. This control over basic order parameter symmetry provides a useful model for understanding imperfect unconventional superconductors. For both phases, the orbital quantization axis is fixed by the direction of strain. Unexpectedly, at a specific temperatureT_x, the orbital axis flops by 90^∘, but in reverse order for A and B-phases. Aided by diffusion limited cluster aggregation simulations of anisotropic aerogel and small angle X-ray measurements, we are able to classify these aerogels as either “planar and “nematic concluding that the orbital-flop is caused by competition between short and long range structures in these aerogels. 

   more » « less
3. Emerging investigator series: 3D printed graphene-biopolymer aerogels for water contaminant removal: a proof of concept

   https://doi.org/10.1039/D0EN00953A  

   Masud, Arvid; Zhou, Chi; Aich, Nirupam (January 2021, Environmental Science: Nano)

   null (Ed.)

   Graphene-based 3D macroscopic aerogels with their hierarchical porous structures and mechanical strength have been widely explored for removing contaminants from water. However, their large-scale manufacturing and application in various water treatment processes are limited by their scalability. In this study, we report a proof-of-concept direct ink writing (DIW) 3D printing technique and subsequent freeze-drying to prepare graphene-biopolymer aerogels for water treatment. To provide appropriate rheology for DIW printability, two bio-inspired polymers, polydopamine (PDA) and bovine serum albumin (BSA), were added to the graphene-based ink. The biopolymers also contributed to the contaminant removal capacity of the resultant graphene-polydopamine-bovine serum albumin (G-PDA-BSA) aerogel. The physicochemical properties of the aerogel were thoroughly characterized from the nano- to macroscale. The 3D printed aerogel exhibited excellent water contaminant removal performance for heavy metals (Cr( vi ), Pb( ii )), organic dyes (cationic methylene blue and anionic Evans blue), and organic solvents ( n -hexane, n -heptane, and toluene) in batch adsorption studies. The electrostatic interaction dominated the removal of heavy metals and dyes while the hydrophobic interaction dominated the removal of organic solvents from water. Moreover, the aerogel showed superb regeneration and reuse potential. The aerogel removed 100% organic solvents over 10 cycles of regeneration and reuse; additionally, the removal efficiencies for methylene blue decreased by 2–20% after the third cycle. The fit-for-design 3D printed aerogel was also effectively used as a bottle-cap flow-through filter for dye removal. The potential and vision of the 3D printing approach for graphene-based water treatment presented here can be extended to other functional nanomaterials, can enable shape-specific applications of fit-for-purpose adsorbents/reactors and point-of-use filters, and can materialize the large-scale manufacturing of nano-enabled water treatment devices and technologies. 

   more » « less
4. Direct ink writing of piezoresistive isoprene rubber nanocomposites

   https://doi.org/10.1002/pc.29535  

   Banks, James D; Emami, Anahita (July 2025, Polymer Composites)

   Abstract Despite the growing interest in flexible electronics and wearable sensors, research in piezoresistive polymer nanocomposites has stagnated in consideration of the polymer matrices, particularly in additive manufacturing (AM) applications. This research focuses on using a low‐molecular isoprene rubber (IR) as a matrix filled with carbonaceous nanoparticles conductive carbon black (CCB) and carbon nanotubes (CNT) to create piezoresistive sensors printed via direct ink writing (DIW). Using IR as a matrix not only provides an avenue for an alternate sensor matrix, but also offers a distinct advantage for retrofit sensor applications to other diene rubber substrates due to both the feedstock and substrate possessing the same vulcanization mechanism. Thereby, the rheological, mechanical, and piezoresistive properties of the IR nanocomposites are fully investigated, with emphasis on non‐ambient conditions (temperature and durability). In this work it is shown that while CCB exhibits a lower gauge factor (between 1.5 and 8) across all strain rates, strain ranges, and temperatures when compared to CNT compounds (gauge factors between 1.5 and 260), CCB compounds possess better linearity, less temperature deviation, and overall better performance under cyclic loading conditions. This is followed by demonstrations for real‐world applications, including the direct‐to‐product printing of a CCB strain gauge on a chloroprene rubber substrate. HighlightsAM via DIW of piezoresistive isoprene sensors filled with conductive CB and multi‐wall carbon nanotubes.Printed samples capable of achieving tensile strength >3.5 MPa.CB sensors showed less sensitivity, but better durability and repeatability compared to carbon nanotube filled sensors.Piezoresistive isoprene strain gauge printed on chloroprene substrate with direct adhesion. 

   more » « less
5. Micro-void nucleation at fiber-tips within the microstructure of additively manufactured polymer composites bead

   https://doi.org/10.1016/j.compositesa.2024.108629  

   Awenlimobor, Aigbe; Sayah, Neshat; Smith, Douglas E (March 2025, Composites Part A: Applied Science and Manufacturing)

   The presence of voids within the microstructure of short carbon fiber polymer composites produced by additive manufacturing (AM) technology are known to alter the expected material behavior that impair part performance. Previous research efforts aimed at understanding the formation mechanisms of these micro-voids during the polymer extrusion/deposition process have not kept up with the advancement of this AM technology. The present study investigates the phenomenon of micro-void nucleation at the fiber/matrix interface, especially those that form at fiber tips, by characterizing the microstructural configuration of a 13 % carbon fiber filled ABS polymer composite print bead specimen using 3D X-ray micro computed tomography image acquisition and analysis. The results reveal a high level of micro-voids segregation at the ends of fibers that are relatively larger in size and less spherical as compared to micro-voids isolated within the ABS matrix. Additionally, by simulating the hydrostatic flow-field pressure distribution surrounding a single rigid ellipsoidal fibre in colloidal suspension using Jeffery’s model equations, we show that the pressure drops to a critical value at the fibre tips where the micro-voids nucleation is experimentally observed to occur. The study helps to improve our understanding of the potential mechanisms that may be responsible for micro-void development within beads printed with extrusion/ deposition AM. 

   more » « less