Linear reciprocating tribometer for in situ neutron reflectometry of soft matter
Data files
Aug 19, 2025 version files 1.49 MB
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2025-07-17-TribLett-Shaffer-Data.zip
1.48 MB
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README.md
7.12 KB
Abstract
Neutron reflectometry is a technique for measuring structure near planar interfaces that has been previously used to non-destructively characterize the polymer density of hydrated, dilute, and soft materials. Previous investigations have conducted neutron reflectometry measurements of liquids, gels, emulsion, and polymer solutions at rest, in compression, and subject to shear stress. However, correlating structure with tribological properties of soft materials presents significant experimental challenges for prior instruments due to wall slip, sample thickness, and structural heterogeneity (eg., depth-wise gradients). A linear reciprocating tribometer offers several advantages for in situ neutron reflectometry studies, including: uniform velocity profiles, constant shear stress over large regions of interest, and independent control of normal force and sliding velocity during measurements. This work outlines basic considerations for the design of a custom linear reciprocating tribometer that operates in a neutron beamline and includes commissioning measurements. The tribometer is designed to compress soft and hydrated materials against linearly reciprocating silicon disks. The three key design considerations for this tribometer are (1) safety, (2) neutron transmission, and (3) sample positioning. This instrument design will enable in situ studies of soft matter and illuminate the role of interfacial structure on tribological phenomena.
Dataset DOI: 10.5061/dryad.bg79cnpnz
Description of the data and file structure
Data from peer-reviewed article:
Title: Linear Reciprocating Tribometer for In Situ Neutron Reflectometry of Soft Matter
DOI: [Insert link upon acceptance of publication]
Authors: Kathryn E. Shaffer, Brendan Louie Bagorio, Ahmed Al Kindi, Julia J. Ong, Andrew R. Rhode, Erik B. Watkins, Rebecca J. L. Welbourn, Roger Pynn, Juan Manuel Urueña, and Angela A. Pitenis
Corresponding Authors: Angela A. Pitenis apitenis@ucsb.edu
Files and variables
File: 2025-07-17-TribLett-Shaffer-Data.zip
Description:
File List:
A) Fig3_AB_Force_Time.csv
B) Fig3_C_Fn_Histogram.csv
C) Fig3_D_Ff_Histogram.csv
D) Fig4_B_Position1_Reflectivity_Q.csv
E) Fig4_B_Position2_Reflectivity_Q.csv
F) Fig4_B_Motion_Reflectivity_Q.csv
G) Fig4_C_SLD.csv
H) FigS5_AB_Force_Time.csv
I) FigS5_C_Fn_Histogram.csv
J) FigS5_D_Ff_Histogram.csv
K) FigS6_MotionProfile.csv
L) FigS7_MotionProfile.csv
Figure 3: Load cell data
A) Fig3_AB_Force_Time.csv: normal force and friction force data as a function of time recorded by the load cell for a sample holder moving in water but not in contact
* Row 1: labels for column data with units
* Column A: time, in seconds
* Column B: friction force, in newtons
* Column C: normal force, in newtons
B) Fig3_C_Fn_Histogram.csv: histogram binning of normal force data for both the forward and reverse motion directions
* Row 1: labels for column data with units
* Column A: bin center normal force, in newtons
* Column B: forward frequency, in counts
* Column C: reverse frequency, in counts
C) Fig3_D_Ff_Histogram.csv: histogram binning of friction force data for both the forward and reverse motion directions
* Row 1: labels for column data with units
* Column A: bin center friction force, in newtons
* Column B: forward frequency, in counts
* Column C: reverse frequency, in counts
Figure 4: Neutron data
D) Fig4_B_Position1_Reflectivity_Q.csv: reflectivity data and fits for position 1
* Row 1: labels for column data with units
* Column A: Q vector, in inverse angstroms
* Column B: error in Q vector, in inverse angstroms
* Column C: reflectivity, in arbitrary units
* Column D: error in reflectivity, in arbitrary units
* Column E: reflectivity fit, in arbitrary units
E) Fig4_B_Position2_Reflectivity_Q.csv: reflectivity data and fits for position 2
* Row 1: labels for column data with units
* Column A: Q vector, in inverse angstroms
* Column B: error in Q vector, in inverse angstroms
* Column C: reflectivity, in arbitrary units
* Column D: error in reflectivity, in arbitrary units
* Column E: reflectivity fit, in arbitrary units
F) Fig4_B_Motion_Reflectivity_Q.csv: reflectivity data and fits during motion at velocity=5 mm/s
* Row 1: labels for column data with units
* Column A: Q vector, in inverse angstroms
* Column B: error in Q vector, in inverse angstroms
* Column C: reflectivity, in arbitrary units
* Column D: error in reflectivity, in arbitrary units
* Column E: reflectivity fit, in arbitrary units
G) Fig4_C_SLD.csv: scattering length density fitting parameters and confidence intervals
* Row 1: labels for column data
* Column A: parameter labels for scattering length density fits with units
* Column B: value of parameter, with units as indicated in column A
* Column C: parameter's lower value for a 68% confidence interval fit, with units as indicated in column A
* Column D: parameter's upper value for a 68% confidence interval fit, with units as indicated in column A
* Column E: parameter's lower value for a 95% confidence interval fit, with units as indicated in column A
* Column F: parameter's upper value for a 95% confidence interval fit, with units as indicated in column A
* Row 2: neutron signal background for position 1, in arbitrary units
* Row 3: position 1 neutron signal intensity, in arbitrary units
* Row 4: position 1 D2O scattering length density with units of multiplied by ten to the power of negative six angstroms squared
* Row 5: position 2 neutron signal background, in arbitrary units
* Row 6: position 2 neutron signal intensity, in arbitrary units
* Row 7: position 2 D2O scattering length density with units of multiplied by ten to the power of negative six angstroms squared
* Row 8: reciprocating motion neutron signal background, in arbitrary units
* Row 9: reciprocating motion neutron signal intensity, in arbitrary units
* Row 10: reciprocating motion D2O SLD with units of multiplied by ten to the power of negative six angstroms squared
* Row 11: Si roughness, in angstroms
* Row 12: SiO2 interface roughness, in angstroms
* Row 13: SiO2 scattering length density with units of multiplied by ten to the power of negative six angstroms squared
* Row 14: SiO2 thickness, in angstroms
* Row 15: contaminant interface roughness, in angstroms
* Row 16: contaminant scattering length density with units of multiplied by ten to the power of negative six angstroms squared
* Row 17: contaminant thickness, in angstroms
Supplementary Figure S5: Load cell data in an environmental enclosure
H) FigS5_AB_Force_Time.csv: normal force and friction force data as a function of time recorded by the load cell for a sample holder moving in water but not in contact contained in an environmental enclosure
* Row 1: labels for column data with units
* Column A: time, in seconds
* Column B: friction force, in newtons
* Column C: normal force, in newtons
I) FigS5_C_Fn_Histogram.csv: histogram binning of normal force data for both the forward and reverse motion directions
* Row 1: labels for column data with units
* Column A: bin center normal force, in newtons
* Column B: forward frequency, in counts
* Column C: reverse frequency, in counts
J) FigS5_D_Ff_Histogram.csv: histogram binning of normal friction data for both the forward and reverse motion directions
* Row 1: labels for column data with units
* Column A: bin center friction force, in newtons
* Column B: forward frequency, in counts
* Column C: reverse frequency, in counts
Supplementary Figure S6: motion profiles for the tribometer x stage, XT-stage for multiple cycles
K) FigS6_MotionProfile.csv: position, velocity and acceleration with respect to time
* Row 1: labels for column data with units
* Column A: time, in seconds
* Column B: position, in millimeters
* Column C: velocity, in millimeters per second
* Column D: acceleration, in millimeters per second squared
Supplementary Figure S7: motion profiles for the tribometer x stage, XT-stage for one turnaround region
L) FigS7_MotionProfile.csv: position, velocity and acceleration with respect to time
* Row 1: labels for column data with units
* Column A: time, in seconds
* Column B: position, in millimeters
* Column C: velocity, in millimeters per second
* Column D: acceleration, in millimeters per second squared