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Search Publications

NIST Authors in Bold

Displaying 1 - 25 of 1746

Simulated stress mitigation strategies in embedded 3D bioprinting

August 30, 2022
Leanne Friedrich, Ross Gunther, Jonathan Seppala
Extrusion-based 3D bioprinting is a powerful tool for fabricating complex cell-laden constructs. Embedded Ink Writing (EIW) is an extrusion-based printing technique wherein a nozzle embedded into a support bath writes continuous filaments. Because it

Leveraging Theory for Enhanced Machine Learning

August 26, 2022
Debra Audus, Austin McDannald, Brian DeCost
The application of machine learning to the materials domain has traditionally struggled with two major challenges: a lack of large, curated data sets and the need to understand the physics behind the machine-learning prediction. The former problem is

Simulation-guided resonant soft X-ray scattering for determining microstructure of triblock copolymers

August 1, 2022
Eliot Gann, Veronica Reynolds, Michael L. Chabinyc, Christopher Bates, Devon Callan, Elizabeth Murphy, Yan-Qiao Chen, Kaitlin Albanese, Claire Wu, Craig Hawker
Resonant soft X-ray scattering (RSoXS) probes structure with chemical sensitivity that is useful for determining the morphology of multiblock copolymers. However, the hyperspectral data produced by this technique are challenging to interpret. Here, we use

Suppression of filament defects in embedded 3D printing

July 5, 2022
Leanne Friedrich, Ross Gunther, Jonathan Seppala
Embedded 3D printing enables the manufacture of soft, intricate structures. In the technique, a nozzle is embedded into a viscoelastic support bath and extrudes filaments or droplets. While embedded 3D printing expands the printable materials space to low

Polydimethylsiloxane tissue-mimicking phantoms with tunable optical properties

July 1, 2022
Aaron Goldfain, Paul Lemaillet, David W. Allen, Kimberly Briggman, Jeeseong C. Hwang
We report on techniques to manufacture and characterize solid tissue-mimicking phantoms of polydimethylsiloxane (PDMS) polymers. Tunability of the absorption (a()) and reduced scattering spectra (s'()) in the wavelength range of 500 nm to 850 nm is

Time-gated Raman spectroscopy of recovered plastics

July 1, 2022
Anthony Kotula, Sara Orski, Kayla Brignac, Jennifer Lynch, Bryan Heilala
Raman spectroscopy is a powerful non-destructive technique for the identification and characterization of plastics. The technique often has limited use due to fluorescence emission, which often occurs in polymer samples containing colorants or that have

Thermal Shrinkage Reveals the Feasibility of Pulse-delay Photocuring Technique

April 13, 2022
Sri Vikram Palagummi, Taeseung Hong, Li Jiang, Martin Chiang
Objectives: To resolve applicability of the pulse-delay photocuring technique to restorative dental composites as a clinical strategy for the reduction in the detrimental polymerization stress. Methods: Model dental composites with high and low-filler

Coherent anti-Stokes Raman scattering (CARS) microscopy for polymers

April 1, 2022
Shuyu Xu, Charles Camp, Young Jong Lee
Coherent anti-Stokes Raman scattering (CARS) microscopy is a label-free chemical imaging modality capable of interrogating local molecular composition, concentration, and even orientation. In comparison to traditional Raman spectroscopy/imaging, CARS

Resonant X-ray Scattering in Polymer Science

April 1, 2022
Brian Collins, Eliot Gann
Resonant Soft X-ray Scattering (RSoXS) is an emerging, powerful technique to probe the nano-to-mesoscale ordering of polymers and other molecules. It joins together small-angle X-ray scattering (a statistical nanoprobe) with X-ray spectroscopy that brings

A small-volume microcapillary rheometer

March 30, 2022
Paul Salipante, Steve Kuei, Steven Hudson
We demonstrate a capillary device used to measure the shear rate dependent viscosity of microliter scale volumes. Liquid samples are driven pneumatically to fill a microcapillary and partially fill a larger glass capillary. The glass capillary is mounted

Reassessing the Significance of Reduced Aggregation and Crystallinity of Naphthalene Diimide-Based Copolymer Acceptors in All-Polymer Solar Cells

March 28, 2022
Eliot Gann, Christopher McNeill, Doan Vu, Martyn Jervic, Chao Wang, Lars Thomsen, Mats Andersson
Terpolymerization is a facile and effective strategy to control the aggregation and crystallinity of semiconducting polymers which has been exploited to improve the photovoltaic performance of all-polymer solar cells (all-PSCs). Applying this strategy to

Effects of Thermal Aging on Molar Mass of Ultra-High Molar Mass Polyethylene Fibers

March 24, 2022
Zois Tsinas, Sara Orski, Viviana Bentley, Lorelis Gonzalez-Lopez, Mohamad Al-Sheikhly, Amanda L. Forster
Ultra-high molar mass polyethylene (UHMMPE) is commonly used for ballistic-resistant body armor applications due to the superior strength of the fibers fabricated from this material combined with its low density. However, polymeric materials are

Imaging 3D molecular orientation by orthogonal-pair polarization IR microscopy

February 28, 2022
Shuyu Xu, Chad R. Snyder, Jeremy Rowlette, Young Jong Lee
Anisotropic molecular alignment occurs ubiquitously and often heterogeneously in three dimensions (3D). However, conventional imaging approaches based on polarization can map only molecular orientation projected onto the 2D polarization plane. Here, an

Pruning the Mechanical Impedance of Three-Dimensional Disordered Networks

February 21, 2022
Marcos Reyes-Martinez, Edwin P. Chan, Christopher Soles, Michael A. Riley, Endao Han, Nidhi Pashine, Kieran Murphy, Heinrich Jaeger, Sidney Nagel, Daniel Reid, Meng Shen, Juan J. de Pablo
Disordered networks, comprised of random arrangements of bonds and nodes, have emerged as materials with the unique ability for independent control over the shear and bulk moduli. Recent computational studies have demonstrated that an extremely high degree

Predicting the plateau modulus from molecular parameters of conjugated polymers

January 18, 2022
Abigail Fenton, Renxuan Xie, Melissa Aplan, Youngmin Lee, Michael Gill, Ryan Fair, Fabian Kempe, Michael Sommer, Chad R. Snyder, Enrique Gomez, Ralph Colby
The relationship between Kuhn length lk, Kuhn monomer volume v0, and plateau modulus GN0 , initially proposed by Graessley and Edwards for flexible polymers, and extended by Everaers, has a large gap in experimental data between the flexible and stiff

Orientation of Thin Polyamide Layer-by-Layer Films on Non-Porous Substrates

December 16, 2021
Tawanda J. Zimudzi, Sarah E. Sheffield, Kathleen E. Feldman, Peter Beaucage, Dean DeLongchamp, Douglas I. Kushner, Christopher Stafford, Michael A. Hickner
The orientation of polyamide thin films on non-porous substrates was investigated using Fourier transform infrared (FTIR) spectroscopy and corroborated by near edge X-ray absorption fine structure (NEXAFS) measurements. Polyamide films comprised of m
Displaying 1 - 25 of 1746