DOI: 10.5061/dryad.ksn02v7dv
title: Sliding on slide-ring gels

description: Recent investigations have pointed to physical entanglements that greatly
 outnumber chemical crosslinks as key sources of energy dissipation and low
 friction in hydrogel networks. Slide-ring gels are an emerging class of
 hydrogels described by their mobile crosslinks, which are formed by rings
 topologically constrained to slide along linear polymer chains within the
 network. These materials have enjoyed decades of study by polymer chemists
 but have been underexplored by the tribology community. In this work, we
 synthesized a pseudo-rotaxane crosslinker from poly(ethylene glycol)
 diacrylate (PEG-diacrylate) and α-cyclodextrin-acrylate followed by
 hydrogel networks by connecting the sliding crosslinks with polyacrylamide
 chains. The mechanical and tribological properties of slide-ring hydrogels
 were investigated using a custom-built microtribometer. Slide-ring
 hydrogels exhibit unique behavior compared to conventional
 covalently-crosslinked polyacrylamide hydrogels and offer a vast design
 space for future investigations.
description: Microindentations and sliding experiments were conducted with a
 custom-built linear reciprocating tribometer. Data was analyzed and
 processed with the following Matlab codes Compiling_Friction_Data_v5 and
 Tribometer_Indent_Analysis_v3_Wad NMR spectroscopy was
 conducted with a Varian VNMRS 600 MHz spectrometer using
 D<sub>2</sub>O as a solvent. In all cases, the number of scans
 was 32, and the relaxation time was 1 s. The data files were processed in
 MestReNova. Using MestReNova, NMR CSV files were generated for this
 repository.
description: # Sliding on slide-ring gels
 [https://doi.org/10.5061/dryad.ksn02v7dv](https://doi.org/10.5061/dryad.ksn02v7dv) ### Description of the data and file structure ### Data from: Sliding on Slide-Ring Gels Article DOI: 10.1007/s11249-024-01920-x ### **Authors:** Andrew R. Rhode, University of California, Santa Barbara Iván Montes de Oca, Universidade da Coruña Michael L. Chabinyc, University of California, Santa Barbara Christopher M. Bates, University of California, Santa Barbara Angela A. Pitenis, University of California, Santa Barbara, [apitenis@ucsb.edu](mailto:apitenis@ucsb.edu) ### Files and variables #### File: 2024\_Rhode\_TribLett\_Dataset.zip ### File List A) Table_1.csv B) Fig_2a.csv C) Fig_2b.csv D) Fig_2c.csv E) Fig_3a.csv F) Fig_3b.csv G) Fig_3c.csv H) Fig_4a.csv I) Fig_4b.csv J) Fig_S1.csv K) Fig_S2.csv L) Table_S1.csv L) Fig_S3.csv A) Table_1.csv Column 1: Concentration of acrylamide in the gel precursor solution in wt% Column 2: Concentration of pseudo-rotaxane in the gel precursor solution in wt% Column 3: Concentration of ammonium persulfate (APS) in the gel precursor solution in wt% Column 4: Concentration of N,N,N',N'-Tetramethylethylenediamine (TEMED) in the gel precursor solution in wt% Column 5: Concentration of water in the gel precursor solution in wt% Figure 2: Indentation data B) Fig_2a.csv Column 1: position of probe in micrometers for a 1.0 wt% sample indent (x) Column 2: Normal force in micronewtons for a 1.0 wt% sample indent (y) Column 3: position of probe in micrometers for a 1.5 wt% sample indent (x) Column 4: Normal force in micro newtons for a 1.5 wt% sample indent (y) C) Fig_2b.csv Column 1: position of probe in micrometers for a 1.0 wt% sample indent with a 10 minute hold at the maximum force (x) Column 2: Normal force in micronewtons for a 1.0 wt% sample with a 10 minutes hold at the maximum force (y) D) Fig_2c.csv Column 1: Sample identifications Column 2: Dwell time in seconds (x) Column 3: average Work of adhesion in microjoules (y) Column 4: Standard deviation of work of adhesion in microjoules (+/- y) Rows 2-5: Data for 1.0 wt% cross linked sample 2 Rows 8-11: Data for 1.5 wt% cross linked sample 1 Figure 3: Friction data E) Fig_3a.csv Column 1: Lateral position of the probe in micrometers for the 10 micron per second loop (x) Column 2: Friction force in micronewtons for the 10 micron per second loop (y) Column 3: Lateral position of the probe in micrometers for the 100 micron per second loop (x) Column 4: Friction force in micronewtons for the 100 micron per second loop (y) Note: Raw data has been shifted to align with the region of 0 to 6000 micrometers. Figure 3a is plotted with the position in millimeters on the x axis for visual clarity. 1 millimeter is 1000 micrometers. The friction loops in Fig 3a come from 1.5 wt% sample 1 F) Fig_3b.csv Column 1: Lateral position of the probe in micrometers for the 10 micron per second loop (x). Column 2: Friction force in micronewtons for the 10 micron per second loop (y) Column 3: Lateral position of the probe in micrometers for the 100 micron per second loop (x). Column 4: Friction force in micronewtons for the 100 micron per second loop (y) Note: Raw data has been shifted to align with the region of 0 to 6000 micrometers. Figure 3a is plotted with the position in millimeters on the x axis for visual clarity. 1 millimeter is 1000 micrometers. The friction loops in Fig 3a come from 1.0 wt% sample 2 G) Fig_3c.csv Column 1: Sample identifier Column 2: velocity in micrometers per second and force in micronewtons of the friction measurements Column 3: Average Hertz reduced modulus determined from indentation measurements of 5 repeats on 3 sites of 2 samples Column 4: Standard deviation of Hertz reduced modulus determined from indentation measurements of 5 repeats on 3 sites of 2 samples Column 5: Sliding speed in micrometers per second (x) Column 6: Measurement normal force in micronewtons Column 7: Average friction coefficient across two measurements for each formulation and set of parameters (y) Column 8: Standard deviation of friction coefficient across two measurements for each formulation and set of parameters (+/- y) Column 9: Average friction force in micronewtons across two measurements for each formulation and set of parameters Column 10: Standard deviation of friction force in micronewtons across two measurements for each formulation and set of parameters Column 11: Average normal force in micronewtons across two measurements for each formulation and set of parameters Column 12: Standard deviation of normal force in micronewtons across two measurements for each formulation and set of parameters Note: Rows 2-6 correspond to measurements of 1.0 wt% cross linked gels. Rows 8-12 correspond to measurements of 1.5 wt% cross linked gels. Figure 3c plots only the average and standard deviation of friction coefficient (columns 7 and 8) against sliding speed (column 5) for measurements with normal force of 500 micronewtons (rows 2,3,4, 8,9,10) Figure 4. Comparison of slide-ring and fixed cross linked hydrogels H) Fig_4a.csv Column 1: Sample name Column 2: Average hertz reduced modulus in kilopascals across both samples of a given type (x) Column 3: Standard deviation of hertz reduced modulus in kilopascals across both samples of a given type (+/- x) Column 4: Sliding speed of friction measurements in micrometers per second Column 5: Target normal force of friction measurements in micronewtons Column 6: Average friction coefficient resulting from sliding experiments on two samples of the same formulation with the same target normal force and sliding speed (y) Column 7: Standard deviation of friction coefficient resulting from sliding experiments on two samples of the same formulation with the same target normal force and sliding speed (+/- y) Column 8: Average friction force resulting from sliding experiments on two samples of the same formulation with the same target normal force and sliding speed Column 9: Standard deviation of friction force resulting from sliding experiments on two samples of the same formulation with the same target normal force and sliding speed Column 10: Average normal force resulting from sliding experiments on two samples of the same formulation with the same target normal force and sliding speed Column 11: Standard deviation of normal force resulting from sliding experiments on two samples of the same formulation with the same target normal force and sliding speed Note: Only the data for sliding speed 100 micrometers per second and normal force 500 micronewtons are plotted in Figure 4a. This corresponds to Rows 2 and 8. The columns plotted are 2 (x), 3 (+/- x), 6 (y), and 7 (+/- y) I) Fig_4b.csv Column 1: Sample name Column 2: Average Hertz reduced modulus in kilopascals Column 3: Standard deviation of Hertz reduced modulus in kilopascals Column 4: Sliding speed in micrometers per second Column 5: Average normal force of sliding experiment in micronewtons Column 6: Standard deviation of normal force of sliding experiment in micronewtons Column 7: Average friction force of sliding experiment in micronewtons Column 8: Standard deviation of friction force of sliding experiment in micronewtons Column 9: Average friction coefficient of sliding experiment (y) Column 10: Standard deviation of friction coefficient of sliding experiment (+/- y) Column 11: Calculated fluid film thickness resulting from each sliding experiment in nanometers (y) Note: The average and standard deviation of friction coefficient for 1.0wt% sample 1 (columns 9-10, row 15) are intentionally left blank, as this measurement resulted in a friction coefficient below the noise floor of the tribometer. Fig 4b plots column 9 (y) and 10 (+/- y) against column 11 (x) J) Fig_S1.png: Image of pseudo-rotaxane solutions The leftmost vial is pseudo-rotaxane solution. The middle vial is a solution of alpha-cyclodextrin-acrylate. The rightmost vial is pure DI water K) Fig_S2.csv: NMR Row 1 has sample identifications for internal use only Column 1: Chemical shift (horizontal axis) in parts per million (ppm) (x) Column 2: Intensity (arbitrary units) of signal for PEG-Diacrylate (y) Column 3: Intensity (arbitrary units) of signal for alpha-cyclodextrin-acrylate (y) Column 4: Intensity (arbitrary units) of signal for pseudo-rotaxane complex made from mixing PEG-Diacrylate and alpha-cyclodextrin-acrylate (y) L) Table_S1.csv: Swelling measurements of slide-ring gels Column 1: Sample name Column 2: Ratio of final diameter to initial diameter Column 3: Cubed ratio of final to initial diameter M) Fig_S3 Column 1: Lateral position in micrometers (x) Column 2: friction coefficient (y) Note: The data has been shifted to align with the position range of 0 to 6000 micrometers and to align free sliding regime in the middle millimeter of the sliding path with the friction coefficient value of 0 N) Indents_Slidering.csv Column 1: Names of cycles for internal use Column 2: Radius of curvature of glass probe in millimeters Column 3: Maximum force for hertz fit for determination of reduced modulus Column 4: Hertz reduced modulus for one cycle Column 5: Maximum adhesive force in a given cycle in micronewtons Column 6: Maximum normal force in a given cycle in micronewtons Column 7: Work of adhesion for a given cycle in microjoules Table 1: Data for indents on 1.5 wt% Sample 1 (Rows 2-18) Table 2: Data for indents on 1.5 wt% Sample 2 (Rows 21-37) Table 3: Data for indents on 1.0 wt% Sample 1 (Rows 41-58) Table 4: Data for indents on 1.0 wt% Sample 2 (Rows 60-76) Note: At the end of each table, the average and standard deviation of the Hertz reduced modulus for the corresponding sample are calculated. The second to last row of each table is the average, and the last row is the standard deviation. All indentation measurements in this file use a constant speed of 10 micrometers per second O) Indent_hold.csv Column 1: Name of cycle for internal use Column 2: Probe radius of curvature in millimeters Column 3: The maximum normal force in micronewtons during a given adhesion measurement Column 4: The maximum adhesive force in micronewtons during a given adhesion measurement Column 5: The work of adhesion in microjoules for a given adhesion measurement Table 1 (rows 3-16) have data for 1.5 wt% sample 1 with a dwell time of 0 seconds Table 2 (rows 3-16) have data for 1.5 wt% sample 1 with a dwell time of 10 seconds Table 3 (rows 3-16) have data for 1.5 wt% sample 1 with a dwell time of 60 seconds Table 4 (rows 3-16) have data for 1.5 wt% sample 1 with a dwell time of 600 seconds Table 5 (rows 3-16) have data for 1.0 wt% sample 2 with a dwell time of 0 seconds Table 6 (rows 3-16) have data for 1.0 wt% sample 2 with a dwell time of 10 seconds Table 7 (rows 3-16) have data for 1.0 wt% sample 2 with a dwell time of 60 seconds Table 8 (rows 3-16) have data for 1.0 wt% sample 2 with a dwell time of 600 seconds The second to last row in each table contains the average value for the maximum normal force, maximum adhesive force, and work of adhesion across all measurements of one sample with one dwell time Note: All indentation measurements in this file used a target maximum force of 1000 micronewtons and had a constant indentation speed of 5 micrometers per second ## Code/software Matlab codes are provided ias .txt files. ##