DOI: 10.5061/dryad.280gb5mzv
title: Photoresponsive Hydrogel Friction

description: Photoresponsive hydrogels are an emerging class of stimuli-responsive
 materials that exhibit changes in physical or chemical properties in
 response to light. Previous investigations have leveraged photothermal
 mechanisms to achieve reversible changes in hydrogel friction, although
 few have focused on photochemical means. To date, the tribological
 properties of photoswitchable hydrogels (e.g., friction and lubrication)
 have remained underexplored. In this work, we incorporated photoresponsive
 methoxy-spiropyran-methacrylate monomers (methoxy-SP-MA) into a hydrogel
 network to form a copolymerized system of
 poly(N-isopropylacrylamide-co-2-acrylamido-2-methylpropane sulfonic
 acid-co-methoxy-spiropyran-methacrylate) (p(NIPAAm-co-AMPS-co-SP)). We
 demonstrated repeatable photoresponsive changes to swelling, friction, and
 stiffness over three light cycles. Our findings suggest that volume
 changes driven by the decreased hydrophilicity of the methoxy-SP-MA upon
 light irradiation are responsible for differences in the mechanical and
 tribological properties of our photoresponsive hydrogels. Our results
 could inform future designs of photoswitchable hydrogels for applications
 ranging from biomedical applications to soft robotics.
description: # Photoresponsive Hydrogel Friction
 [https://doi.org/10.5061/dryad.280gb5mzv](https://doi.org/10.5061/dryad.280gb5mzv) ## Description of the data and file structure Data from peer-reviewed article: Title: Photoresponsive Hydrogel Friction Journal: Soft Matter Authors: Allison L. Chau*, Kseniia M. Karnaukh*, Ian Maskiewicz, Javier Read de Alaniz, and Angela A. Pitenis *co-first author Corresponding author: Javier Read de Alaniz ([javier@chem.ucsb.edu](mailto:javier@chem.ucsb.edu)), Angela Pitenis ([apitenis@ucsb.edu](mailto:apitenis@ucsb.edu)) ### Files and variables #### File: 2024\_ChauKarnaukh\_SoftMatter\_Dataset.zip **Description:**  \------------------------------------------------------------------------------------------- File List A) Fig1b.csv B) Fig2a.csv C) Fig2b.csv D) Fig3a.csv E) Fig3b.csv F) Fig4b_side_DSC_13253_0min.jpg G) Fig4b_side_DSC_13264_1min.jpg H) Fig4b_side_DSC_13276_2min.jpg I) Fig4b_side_DSC_13288_3min.jpg J) Fig4b_side_DSC_13312_5min.jpg K) Fig4b_side_DSC_13372_10min.jpg L) Fig4b_top_SampleR4b_before_20min_13196.jpg M) Fig4b_top_SampleR4b_after_20min_13228.jpg N) Fig5.csv O) Fig6a_S15a.csv P) Fig6b.csv Q) Fig6c.csv R) Fig6d.csv S) FigS1.csv T) FigS2.csv U) FigS3.csv V) FigS4.csv W) FigS5.csv X) FigS6.csv Y) FigS7.csv Z) FigS8a.csv AA) FigS8b.csv AB) FigS9a.csv AC) FigS9b.csv AD) FigS10a.csv AE) FigS10b.csv AF) FigS11a.csv AG) FigS11b.csv AH) FigS11c.csv AI) FigS12a.csv AJ) FigS12b.csv AK) FigS12c.csv AL) FigS12d.csv AM) FigS13.csv AN) FigS14a.csv AO) FigS14b.csv AP) FigS14c.csv AQ) FigS14d.csv AR) FigS14e.csv AS) FigS14f.csv AT) FigS15b.csv AU) FigS15c.csv AV) FigS15d.csv AW) FigS15e.csv AX) FigS15f.csv AY) FigS16a.csv AZ) FigS16b.csv BA) FigS16c.csv BB) FigS17a.csv BC) FigS17b.csv BD) FigS17c.csv BE) Manuscript_mechanics_compilation.csv BF) Manuscript_swelling_FigS13.csv BG) Manuscript_swelling_compilation.csv FIGURE 1: UV-Vis spectroscopy of monomers \------------------------------------------------------------------------------------------- A) Fig1b.csv: UV-Vis spectra of methoxy-spiropyran-methacrylate monomer \- row 1: x and y axis, corresponding to wavelength (x) and absorbance (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- row 3: light state \- dataset 1: 470 nm (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + B \- dataset 2: dark (30 min) - wavelength (x) and absorbance (y) -&gt; columns A + C \- dataset 3: dark (60 min) - wavelength (x) and absorbance (y) -&gt; columns A + D \- dataset 4: dark (90 min) - wavelength (x) and absorbance (y) -&gt; columns A + E \- dataset 5: dark (120 min) - wavelength (x) and absorbance (y) -&gt; columns A + F \- dataset 6: dark (150 min) - wavelength (x) and absorbance (y) -&gt; columns A + G \- row 4 and beyond: data \------------------------------------------------------------------------------------------- FIGURE 2: representative indentation curves and friction force loops \------------------------------------------------------------------------------------------- B) Fig2a.csv: representative indentation curves \- row 1: x and y axis, corresponding to indentation depth (x) and normal force (y) \- row 2: units for corresponding axes \- row 3: sample identifier (internal use) \- row 4 and beyond: data C) Fig2b.csv: representative friction force loops \- row 1: x and y axis, corresponding to x position (x) and friction force (y) \- row 2: units for corresponding axes \- row 3: sample identifier (internal use) \- row 4 and beyond: data \------------------------------------------------------------------------------------------- FIGURE 3: linear polymer kinetics data \------------------------------------------------------------------------------------------- D) Fig3a.csv: UV-Vis spectra of linear p(NIPAAm-co-AMPS-co-SP) \- row 1: x and y axis, corresponding to wavelength (x) and absorbance (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- row 3: light state \- dataset 1: 470 nm (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + B \- dataset 2: dark (30 min) - wavelength (x) and absorbance (y) -&gt; columns A + C \- dataset 3: dark (60 min) - wavelength (x) and absorbance (y) -&gt; columns A + D \- dataset 4: dark (90 min) - wavelength (x) and absorbance (y) -&gt; columns A + E \- dataset 5: dark (120 min) - wavelength (x) and absorbance (y) -&gt; columns A + F \- dataset 6: dark (150 min) - wavelength (x) and absorbance (y) -&gt; columns A + G \- row 4 and beyond: data E) Fig3b.csv: pump probe kinetics measurements of linear p(NIPAAm-co-AMPS-co-SP) \- row 1: x and y axis, corresponding to time (x) and absorbance at 450 nm (y) \- row 2: units for corresponding axes \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE 4: top and side view of hydrogel timelapse \------------------------------------------------------------------------------------------- F) Fig4b_side_DSC_13253_0min.jpg - side view before photobleaching G) Fig4b_side_DSC_13264_1min.jpg - side view after photobleaching for 1 min H) Fig4b_side_DSC_13276_2min.jpg - side view after photobleaching for 2 min I) Fig4b_side_DSC_13288_3min.jpg - side view after photobleaching for 3 min J) Fig4b_side_DSC_13312_5min.jpg - side view after photobleaching for 5 min K) Fig4b_side_DSC_13372_10min.jpg - side view after photobleaching for 10 min L) Fig4b_top_SampleR4b_before_20min_13196.jpg - top view before photobleaching M) Fig4b_top_SampleR4b_after_20min_13228.jpg - top view after photobleaching for 20 min \------------------------------------------------------------------------------------------- FIGURE 5: volume as a function of time \------------------------------------------------------------------------------------------- N) Fig5b.csv: volume vs. time \- row 1: x and y axis, corresponding to time (x) and volume (y) \- row 2: units for corresponding axes \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE 6: friction coefficient and normalized volume \------------------------------------------------------------------------------------------- O) Fig6a_S15a.csv: friction coefficient vs. time \- row 1: x and y axis, corresponding to time (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- dataset 1: dark (cycle 1) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light (cycle 1) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: dark (cycle 2) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- dataset 4: light (cycle 2) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns J + K + L \- dataset 5: dark (cycle 3) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns M + N + O \- dataset 6: light (cycle 3) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns P + Q + R \- row 4 and beyond: data P) Fig6b.csv: friction coefficient bar charts \- row 1: x and y axis, corresponding to cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light state (MCH - dark, SP - light) \- dataset 1: dark - cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light - cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + D + E \- row 3 and beyond: data Q) Fig6c.csv: normalized volume vs. time \- row 1: x and y axis, corresponding to time (x) and normalized volume average (avg) (y) and normalized volume standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3 and beyond: data R) Fig6d.csv: normalized volume bar charts \- row 1: x and y axis, corresponding to cycle number (x) and normalized volume average (avg) (y) and normalized volume standard deviation (std) (y) \- row 2: light state (MCH - dark, SP - light) \- dataset 1: dark - cycle number (x) and normalized volume average (avg) (y) and normalized volume standard deviation (std) (y) -&gt; columns A + B + C \- dataset 2: light - cycle number (x) and normalized volume average (avg) (y) and normalized volume standard deviation (std) (y) -&gt; columns A + D + E \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S1: NMR spectrum of 5-methoxy-2,3,3-trimethyl-3H-indole \------------------------------------------------------------------------------------------- S) FigS1.csv \- row 1: x and y axis, corresponding to 1H NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 1H (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S2: H-NMR spectrum of 1-(2-hydroxyethyl)-2,3,3-trimethyl-3H-indolium bromide \------------------------------------------------------------------------------------------- T) FigS2.csv \- row 1: x and y axis, corresponding to 1H NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 1H (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S3: C-NMR spectrum of 1-(2-hydroxyethyl)-2,3,3-trimethyl-3H-indolium bromide \------------------------------------------------------------------------------------------- U) FigS3.csv \- row 1: x and y axis, corresponding to 13C NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 13C (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S4: H-NMR spectrum of 2-(5'-methoxy-3',3'-dimethylspiro[chromene-2,2'-indolin]-1'-yl)ethan-1-ol \------------------------------------------------------------------------------------------- V) FigS4.csv \- row 1: x and y axis, corresponding to 1H NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 1H (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S5: C-NMR spectrum of 2-(5'-methoxy-3',3'-dimethylspiro[chromene-2,2'-indolin]-1'-yl)ethan-1-ol \------------------------------------------------------------------------------------------- W) FigS5.csv \- row 1: x and y axis, corresponding to 13C NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 13C (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S6: H-NMR spectrum of 2-(5'-methoxy-3',3'-dimethylspiro[chromene-2,2'-indolin]-1'-yl)ethyl methacrylate \------------------------------------------------------------------------------------------- X) FigS6.csv \- row 1: x and y axis, corresponding to 1H NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 1H (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S7: C-NMR spectrum of 2-(5'-methoxy-3',3'-dimethylspiro[chromene-2,2'-indolin]-1'-yl)ethyl methacrylate \------------------------------------------------------------------------------------------- Y) FigS7.csv \- row 1: x and y axis, corresponding to 13C NMR chemical shift (x) and arbitrary intensity (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- column 1: 13C (ppm) \- column 2: signal/arbitrary intensity \------------------------------------------------------------------------------------------- FIGURE S8: kinetics of methoxy-spiropyran-methacrylate monomer \------------------------------------------------------------------------------------------- Z) FigS8a.csv: UV-Vis spectra of methoxy-spiropyran-methacrylate monomer \- row 1: x and y axis, corresponding to wavelength (x) and absorbance (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- row 3: light state \- dataset 1: 470 nm (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + B \- dataset 2: dark (5 min) - wavelength (x) and absorbance (y) -&gt; columns A + C \- dataset 3: dark (10 min) - wavelength (x) and absorbance (y) -&gt; columns A + D \- dataset 4: dark (20 min) - wavelength (x) and absorbance (y) -&gt; columns A + E \- dataset 5: dark (30 min) - wavelength (x) and absorbance (y) -&gt; columns A + F \- dataset 6: dark (40 min) - wavelength (x) and absorbance (y) -&gt; columns A + G \- dataset 7: dark (50 min) - wavelength (x) and absorbance (y) -&gt; columns A + H \- dataset 8: dark (60 min) - wavelength (x) and absorbance (y) -&gt; columns A + I \- dataset 9: dark (90 min) - wavelength (x) and absorbance (y) -&gt; columns A + J \- dataset 10: dark (120 min) - wavelength (x) and absorbance (y) -&gt; columns A + K \- dataset 11: dark (150 min) - wavelength (x) and absorbance (y) -&gt; columns A + L \- row 4 and beyond: data AA) FigS8b.csv: pump probe kinetics measurements of methoxy-spiropyran-methacrylate monomer \- row 1: x and y axis, corresponding to time (x) and absorbance at 450 nm (y) \- row 2: units for corresponding axes \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S9: UV-Vis spectra \------------------------------------------------------------------------------------------- AB) FigS9a.csv: UV-Vis spectra of linear p(NIPAAm-co-AMPS-co-SP) in 100 mM phosphate buffer \- row 1: x and y axis, corresponding to wavelength (x) and absorbance (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- row 3: light state \- dataset 1: 470 nm (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + B \- dataset 2: dark (5 min) - wavelength (x) and absorbance (y) -&gt; columns A + C \- dataset 3: dark (10 min) - wavelength (x) and absorbance (y) -&gt; columns A + D \- dataset 4: dark (20 min) - wavelength (x) and absorbance (y) -&gt; columns A + E \- dataset 5: dark (30 min) - wavelength (x) and absorbance (y) -&gt; columns A + F \- dataset 6: dark (40 min) - wavelength (x) and absorbance (y) -&gt; columns A + G \- dataset 7: dark (50 min) - wavelength (x) and absorbance (y) -&gt; columns A + H \- dataset 8: dark (60 min) - wavelength (x) and absorbance (y) -&gt; columns A + I \- dataset 9: dark (90 min) - wavelength (x) and absorbance (y) -&gt; columns A + J \- dataset 10: dark (120 min) - wavelength (x) and absorbance (y) -&gt; columns A + K \- dataset 11: dark (150 min) - wavelength (x) and absorbance (y) -&gt; columns A + L \- row 4 and beyond: data AC) FigS9b.csv: UV-Vis spectra of linear p(NIPAAm-co-AMPS-co-SP) in acidified methanol \- row 1: x and y axis, corresponding to wavelength (x) and absorbance (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- row 3: light state \- dataset 1: 470 nm (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + B \- dataset 2: dark (5 min) - wavelength (x) and absorbance (y) -&gt; columns A + C \- dataset 3: dark (10 min) - wavelength (x) and absorbance (y) -&gt; columns A + D \- dataset 4: dark (20 min) - wavelength (x) and absorbance (y) -&gt; columns A + E \- dataset 5: dark (30 min) - wavelength (x) and absorbance (y) -&gt; columns A + F \- dataset 6: dark (40 min) - wavelength (x) and absorbance (y) -&gt; columns A + G \- dataset 7: dark (50 min) - wavelength (x) and absorbance (y) -&gt; columns A + H \- dataset 8: dark (60 min) - wavelength (x) and absorbance (y) -&gt; columns A + I \- dataset 9: dark (80 min) - wavelength (x) and absorbance (y) -&gt; columns A + J \- dataset 10: dark (100 min) - wavelength (x) and absorbance (y) -&gt; columns A + K \- dataset 11: dark (120 min) - wavelength (x) and absorbance (y) -&gt; columns A + L \- dataset 12: dark (140 min) - wavelength (x) and absorbance (y) -&gt; columns A + M \- row 4 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S10: kinetics of p(NIPAAm-co-AMPS-co-SP) hydrogels with 0.5 mol SP \------------------------------------------------------------------------------------------- AD) FigS10a.csv: UV-Vis of p(NIPAAm-co-AMPS-co-SP) hydrogels with 0.5 mol SP \- row 1: x and y axis, corresponding to wavelength (x) and absorbance (y) \- row 2: units for corresponding axes \- row 3: light state \- dataset 1: before 470 nm - wavelength (x) and absorbance (y) -&gt; columns A + B \- dataset 2: 470 nm (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + C \- dataset 3: dark (1 min) - wavelength (x) and absorbance (y) -&gt; columns A + D \- dataset 4: dark (3 min) - wavelength (x) and absorbance (y) -&gt; columns A + E \- dataset 5: dark (5 min) - wavelength (x) and absorbance (y) -&gt; columns A + F \- dataset 6: dark (10 min) - wavelength (x) and absorbance (y) -&gt; columns A + G \- dataset 7: dark (15 min) - wavelength (x) and absorbance (y) -&gt; columns A + H \- dataset 8: dark (20 min) - wavelength (x) and absorbance (y) -&gt; columns A + I \- dataset 9: dark (30 min) - wavelength (x) and absorbance (y) -&gt; columns A + J \- dataset 10: dark (60 min) - wavelength (x) and absorbance (y) -&gt; columns A + K \- dataset 11: dark (90 min) - wavelength (x) and absorbance (y) -&gt; columns A + L \- dataset 12: dark (150 min) - wavelength (x) and absorbance (y) -&gt; columns A + M \- row 4 and beyond: data AE) FigS10b.csv: pump probe kinetics of p(NIPAAm-co-AMPS-co-SP) hydrogels with 0.5 mol SP \- row 1: x and y axis, corresponding to time (x) and absorbance at 450 nm (y) \- row 2: units for corresponding axes, where a.u. stands for arbitrary units \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S11: representative indentation curves \------------------------------------------------------------------------------------------- AF) FigS11a.csv: indentation curves for Sample 1 \- row 1: x and y axis, corresponding to indentation depth (x) and normal force (y) \- row 2: units for corresponding axes \- row 3: light state and sample identifier (internal use) (MCH - dark, SP- light) \- dataset 1: dark cycle 1 - indentation depth (x) and normal force (y) --&gt; columns A + B \- dataset 2: light cycle 1 - indentation depth (x) and normal force (y) --&gt; columns C + D \- dataset 3: dark cycle 2 - indentation depth (x) and normal force (y) --&gt; columns E + F \- dataset 4: light cycle 2 - indentation depth (x) and normal force (y) --&gt; columns G + H \- dataset 5: dark cycle 3 - indentation depth (x) and normal force (y) --&gt; columns I + J \- dataset 6: light cycle 3 - indentation depth (x) and normal force (y) --&gt; columns K + L \- row 4 and beyond: data AG) FigS11b.csv: indentation curves for Sample 2 \- row 1: x and y axis, corresponding to indentation depth (x) and normal force (y) \- row 2: units for corresponding axes \- row 3: light state and sample identifier (internal use) (MCH - dark, SP- light) \- dataset 1: dark cycle 1 - indentation depth (x) and normal force (y) --&gt; columns A + B \- dataset 2: light cycle 1 - indentation depth (x) and normal force (y) --&gt; columns C + D \- dataset 3: dark cycle 2 - indentation depth (x) and normal force (y) --&gt; columns E + F \- dataset 4: light cycle 2 - indentation depth (x) and normal force (y) --&gt; columns G + H \- dataset 5: dark cycle 3 - indentation depth (x) and normal force (y) --&gt; columns I + J \- dataset 6: light cycle 3 - indentation depth (x) and normal force (y) --&gt; columns K + L \- row 4 and beyond: data AH) FigS11c.csv: indentation curves for Sample 3 \- row 1: x and y axis, corresponding to indentation depth (x) and normal force (y) \- row 2: units for corresponding axes \- row 3: light state and sample identifier (internal use) (MCH - dark, SP- light) \- dataset 1: dark cycle 1 - indentation depth (x) and normal force (y) --&gt; columns A + B \- dataset 2: light cycle 1 - indentation depth (x) and normal force (y) --&gt; columns C + D \- dataset 3: dark cycle 2 - indentation depth (x) and normal force (y) --&gt; columns E + F \- dataset 4: light cycle 2 - indentation depth (x) and normal force (y) --&gt; columns G + H \- dataset 5: dark cycle 3 - indentation depth (x) and normal force (y) --&gt; columns I + J \- dataset 6: light cycle 3 - indentation depth (x) and normal force (y) --&gt; columns K + L \- row 4 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S12: bar charts of reduced elastic modulus \------------------------------------------------------------------------------------------- AI) FigS12a.csv: bar chart of reduced elastic modulus for Sample 1 \- row 1: x and y axis, corresponding to cycle number (x) and elastic modulus averages (avg) (y) and elastic modulus standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark ,SP - light) \- dataset 1: dark - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + B + C \- dataset 2: light - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + D + E \- row 4 and beyond: data AJ) FigS12b.csv: bar chart of reduced elastic modulus for Sample 2 \- row 1: x and y axis, corresponding to cycle number (x) and elastic modulus averages (avg) (y) and elastic modulus standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark ,SP - light) \- dataset 1: dark - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + B + C \- dataset 2: light - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + D + E \- row 4 and beyond: data AK) FigS12c.csv: bar chart of reduced elastic modulus for Sample 3 \- row 1: x and y axis, corresponding to cycle number (x) and elastic modulus averages (avg) (y) and elastic modulus standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark ,SP - light) \- dataset 1: dark - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + B + C \- dataset 2: light - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + D + E \- row 4 and beyond: data AL) FigS12d.csv: bar chart of reduced elastic modulus for averages of Samples 1-3 \- row 1: x and y axis, corresponding to cycle number (x) and elastic modulus averages (avg) (y) and elastic modulus standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark ,SP - light) \- dataset 1: dark - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + B + C \- dataset 2: light - cycle number (x) and elastic modulus avg (y) and elastic modulus std (y) --&gt; columns A + D + E \- row 4 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S13: volume change bar chart \------------------------------------------------------------------------------------------- AM) FigS13.csv: volume change bar chart \- row 1: x and y axis, corresponding to sample (x) and volume change (avg) (y) and volume change standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S14: friction coefficient vs. reciprocating cycle \------------------------------------------------------------------------------------------- AN) FigS14a.csv: friction coefficient vs. reciprocating cycle in the dark for Sample 1 \- row 1: x and y axis, corresponding to reciprocating cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light cycle number \- dataset 1: dark cycle 1 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: dark cycle 2 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: dark cycle 3 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- row 3 and beyond: data AO) FigS14b.csv: friction coefficient vs. reciprocating cycle in the dark for Sample 2 \- row 1: x and y axis, corresponding to reciprocating cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light cycle number \- dataset 1: dark cycle 1 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: dark cycle 2 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: dark cycle 3 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- row 3 and beyond: data AP) FigS14c.csv: friction coefficient vs. reciprocating cycle in the dark for Sample 3 \- row 1: x and y axis, corresponding to reciprocating cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light cycle number \- dataset 1: dark cycle 1 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: dark cycle 2 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: dark cycle 3 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- row 3 and beyond: data AQ) FigS14d.csv: friction coefficient vs. reciprocating cycle in the light for Sample 1 \- row 1: x and y axis, corresponding to reciprocating cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light cycle number \- dataset 1: light cycle 1 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light cycle 2 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: light cycle 3 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- row 3 and beyond: data AR) FigS14e.csv: friction coefficient vs. reciprocating cycle in the light for Sample 2 \- row 1: x and y axis, corresponding to reciprocating cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light cycle number \- dataset 1: light cycle 1 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light cycle 2 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: light cycle 3 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- row 3 and beyond: data AS) FigS14f.csv: friction coefficient vs. reciprocating cycle in the light for Sample 3 \- row 1: x and y axis, corresponding to reciprocating cycle number (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light cycle number \- dataset 1: light cycle 1 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light cycle 2 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: light cycle 3 - reciprocating cycle number (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- row 3 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S15: friction coefficients \------------------------------------------------------------------------------------------- AT) FigS15b.csv: friction coefficient vs. time for Sample 2 \- row 1: x and y axis, corresponding to time (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- dataset 1: dark (cycle 1) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light (cycle 1) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: dark (cycle 2) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- dataset 4: light (cycle 2) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns J + K + L \- dataset 5: dark (cycle 3) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns M + N + O \- dataset 6: light (cycle 3) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns P + Q + R \- row 4 and beyond: data AU) FigS15c.csv: friction coefficient vs. time for Sample 3 \- row 1: x and y axis, corresponding to time (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- dataset 1: dark (cycle 1) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light (cycle 1) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns D + E + F \- dataset 3: dark (cycle 2) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns G + H + I \- dataset 4: light (cycle 2) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns J + K + L \- dataset 5: dark (cycle 3) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns M + N + O \- dataset 6: light (cycle 3) - time (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns P + Q + R \- row 4 and beyond: data AV) FigS15d.csv: bar chart for friction coefficients for Sample 1 \- row 1: x and y axis, corresponding to cycle (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light state (MCH - dark, SP - light) \- row 3: sample identifier (internal use) \- row 4 and beyond: data AW) FigS15e.csv: bar chart for friction coefficients for Sample 2 \- row 1: x and y axis, corresponding to cycle (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light state (MCH - dark, SP - light) \- row 3: sample identifier (internal use) \- row 4 and beyond: data AX) FigS15f.csv: bar chart for friction coefficients for Sample 3 \- row 1: x and y axis, corresponding to cycle (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light state (MCH - dark, SP - light) \- row 3: sample identifier (internal use) \- row 4 and beyond: data \------------------------------------------------------------------------------------------- FIGURE S16: data for pNIPAAm \------------------------------------------------------------------------------------------- AY) FigS16a.csv: normalized volume bar charts \- row 1: x and y axis, corresponding to sample (x) and normalized volume average (avg) (y) and normalized volume standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- dataset 1: dark state - sample (x) and normalized volume avg (y) and normalized volume std (y) -&gt; columns A + B + C \- dataset 2: light state - sample (x) and normalized volume avg (y) and normalized volume std (y) -&gt; columns A + D + E \- row 4 and beyond: data AZ) FigS16b.csv: friction coefficient bar charts \- row 1: x and y axis, corresponding to sample (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- dataset 1: dark state - sample (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + B + C \- dataset 2: light state - sample (x) and friction coefficient avg (y) and friction coefficient std (y) -&gt; columns A + D + E \- row 4 and beyond: data BA) FigS16c.csv: reduced elastic modulus bar charts \- row 1: x and y axis, corresponding to sample (x) and elastic modulus average (avg) (y) and elastic modulus standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- dataset 1: dark state - sample (x) and elastic modulus avg (y) and elastic modulus std (y) -&gt; columns A + B + C \- dataset 2: light state - sample (x) and elastic modulus avg (y) and elastic modulus std (y) -&gt; columns A + D + E \- row 4 and beyond: data BB) FigS17a.csv: normalized volume bar chart for silanized hydrogel \- row 1: x and y axis, corresponding to cycle (x) and normalized volume (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- row 4 and beyond: data BC) FigS17b.csv: reduced friction coefficient bar chart for silanized hydrogel \- row 1: x and y axis, corresponding to cycle (x) and friction coefficient average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: light state (MCH - dark, SP - light) \- row 3 and beyond: data BD) FigS17c.csv: reduced elastic modulus bar chart for silanized hydrogel \- row 1: x and y axis, corresponding to cycle (x) and elastic modulus average (avg) (y) and friction coefficient standard deviation (std) (y) \- row 2: units for corresponding axes \- row 3: light state (MCH - dark, SP - light) \- row 4 and beyond: data \------------------------------------------------------------------------------------------- Compilation of raw friction coefficient and reduced elastic modulus data \------------------------------------------------------------------------------------------- BE) Manuscript_mechanics_compilation.csv: raw compiled friction coefficient and reduced elastic modulus data from hydrogel samples \- Table 1: elastic modulus data for p(NIPAAm-co-AMPS-co-SP) (A1 - I9) \- row 2: sample identifier (internal use) \- Column A: light state (MCH- dark, SP - light) and cycle number \- Column B + C: reduced elastic modulus average and standard deviation for Sample 1 \- Column D + E: reduced elastic modulus average and standard deviation for Sample 2 \- Column F + G: reduced elastic modulus average and standard deviation for Sample 3 \- Column H + I: reduced elastic modulus average and standard deviation for averages of Sample 1 - 3 \- Table 2: elastic modulus ratios for p(NIPAAm-co-AMPS-co-SP) (K2 - O6) \- row 3: light state ratio (MCH- dark, SP - light) and cycle number \- Column K: cycle number \- Column L: reduced elastic modulus ratio for Sample 1 \- Column M: reduced elastic modulus ratio for Sample 2 \- Column N: reduced elastic modulus ratio for Sample 3 \- Column O: reduced elastic modulus ratio for averages of Sample 1 - 3 \- Table 3: friction coefficient data for p(NIPAAm-co-AMPS-co-SP) (A11 - I19) \- row 12: sample identifier (internal use) \- Column A: light state (MCH- dark, SP - light) and cycle number \- Column B + C: friction coefficient average and standard deviation for Sample 1 \- Column D + E: friction coefficient average and standard deviation for Sample 2 \- Column F + G: friction coefficient average and standard deviation for Sample 3 \- Column H + I: friction coefficient average and standard deviation for averages of Sample 1 - 3 \- Table 4: friction coefficient ratios for p(NIPAAm-co-AMPS-co-SP) (K12 - O16) \- row 13: light state ratio (MCH- dark, SP - light) and cycle number \- Column K: cycle number \- Column L: reduced elastic modulus ratio for Sample 1 \- Column M: reduced elastic modulus ratio for Sample 2 \- Column N: reduced elastic modulus ratio for Sample 3 \- Column O: reduced elastic modulus ratio for averages of Sample 1 - 3 \- Table 5: elastic modulus data for pNIPAAm (A21 - I25) \- row 22: sample identifier (internal use) \- Column A: light state (MCH- dark, SP - light) and cycle number \- Column B + C: reduced elastic modulus average and standard deviation for Sample 1 \- Column D + E: reduced elastic modulus average and standard deviation for Sample 2 \- Column F + G: reduced elastic modulus average and standard deviation for Sample 3 \- Column H + I: reduced elastic modulus average and standard deviation for averages of Sample 1 - 3 \- Table 6: elastic modulus ratios for pNIPAAm (L22 - O24) \- row 23: light state ratio (MCH- dark, SP - light) and cycle number \- Column L: reduced elastic modulus ratio for Sample 1 \- Column M: reduced elastic modulus ratio for Sample 2 \- Column N: reduced elastic modulus ratio for Sample 3 \- Column O: reduced elastic modulus ratio for averages of Sample 1 - 3 \- Table 7: friction coefficient data for pNIPAAm (A27 - I31) \- row 28: sample identifier (internal use) \- Column A: light state (MCH- dark, SP - light) and cycle number \- Column B + C: friction coefficient average and standard deviation for Sample 1 \- Column D + E: friction coefficient average and standard deviation for Sample 2 \- Column F + G: friction coefficient average and standard deviation for Sample 3 \- Column H + I: friction coefficient average and standard deviation for averages of Sample 1 - 3 \- Table 8: friction coefficient ratios for pNIPAAm (L28 - O30) \- row 29: light state ratio (MCH- dark, SP - light) and cycle number \- Column L: reduced elastic modulus ratio for Sample 1 \- Column M: reduced elastic modulus ratio for Sample 2 \- Column N: reduced elastic modulus ratio for Sample 3 \- Column O: reduced elastic modulus ratio for averages of Sample 1 - 3 \- Table 9: elastic modulus data for silanized p(NIPAAm-co-AMPS-co-SP) hydrogel (A33 - C40) \- Column A: light state (MCH- dark, SP - light) and cycle number \- Columns B + C: reduced elastic modulus average and standard deviation \- Table 10: elastic modulus ratio for silanized p(NIPAAm-co-AMPS-co-SP) hydrogel (E34 - G36) \- row 35: light state ratio (MCH- dark, SP - light) and cycle number \- Column E: reduced elastic modulus ratio for cycle 1 \- Column F: reduced elastic modulus ratio for cycle 2 \- Column G: reduced elastic modulus ratio for cycle 3 \- Table 11: friction coefficient data for silanized p(NIPAAm-co-AMPS-co-SP) hydrogel (A42 - C49) \- Column A: light state (MCH- dark, SP - light) and cycle number \- Columns B + C: reduced elastic modulus average and standard deviation \- Table 12: friction coefficient ratio for silanized p(NIPAAm-co-AMPS-co-SP) hydrogel (E43 - G45) \- row 44: light state ratio (MCH- dark, SP - light) and cycle number \- Column E: reduced elastic modulus ratio for cycle 1 \- Column F: reduced elastic modulus ratio for cycle 2 \- Column G: reduced elastic modulus ratio for cycle 3 \------------------------------------------------------------------------------------------- Compilation of raw swelling data \------------------------------------------------------------------------------------------- BF) Manuscript_swelling_FigS13.csv: raw compiled volume data used to plot Fig S13 \- row 1: sample (x), cycle time, diameter, height, volume, volume change (y) \- row 2: units for corresponding axes \- Column A: sample identifier (internal use) \- Column B: cycle time \- Column C: hydrogel diameter \- Column D: hydrogel height \- Column E: hydrogel volume (assuming cylinder) \- Column F: volume change BG) Manuscript_swelling_compilation.csv: raw compiled modulus data from hydrogel samples \- Table 1: volume measurements (A1 - T15) \- row 2: sample identifier (internal use) \- Column A: light state (MCH- dark, SP- light) and cycle number \- Column B + C: volume average and standard deviation for Sample F2a \- Column D + E: volume average and standard deviation for Sample G4a \- Column F + G: volume average and standard deviation for Sample G5a \- Column H + I: volume average and standard deviation for Sample Q1 \- Column J + K: volume average and standard deviation for Sample Q2 \- Column L + M: volume average and standard deviation for Sample Q3 \- Column N + O: volume average and standard deviation for Sample O1 \- Column P + Q: volume average and standard deviation for Sample O2 \- Column R + S: volume average and standard deviation for Sample O3 \- Column T: volume average for Sample R1 (silanized gel) \- Table 2: volume change measurements (A16 - T30) \- row 18: sample identifier (internal use) \- Column A: light state (MCH- dark, SP- light) and cycle number \- Column B + C: volume change average and standard deviation for Sample F2a \- Column D + E: volume change average and standard deviation for Sample G4a \- Column F + G: volume change average and standard deviation for Sample G5a \- Column H + I: volume change average and standard deviation for Sample Q1 \- Column J + K: volume change average and standard deviation for Sample Q2 \- Column L + M: volume change average and standard deviation for Sample Q3 \- Column N + O: volume change average and standard deviation for Sample O1 \- Column P + Q: volume change average and standard deviation for Sample O2 \- Column R + S: volume change average and standard deviation for Sample O3 \- Column T: volume change average for Sample R1 (silanized gel) \- Table 3: normalized volume (A32 - T46) \- row 33: sample identifier (internal use) \- Column A: light state (MCH- dark, SP- light) and cycle number \- Column B + C: normalized volume average and standard deviation for Sample F2a \- Column D + E: normalized volume average and standard deviation for Sample G4a \- Column F + G: normalized volume average and standard deviation for Sample G5a \- Column H + I: normalized volume average and standard deviation for Sample Q1 \- Column J + K: normalized volume average and standard deviation for Sample Q2 \- Column L + M: normalized volume average and standard deviation for Sample Q3 \- Column N + O: normalized volume average and standard deviation for Sample O1 \- Column P + Q: normalized volume average and standard deviation for Sample O2 \- Column R + S: normalized volume average and standard deviation for Sample O3 \- Column T: normalized volume average for Sample R1 (silanized gel) \- Table 4: normalized volume*100 (A48 - T62) \- row 49: sample identifier (internal use) \- Column A: light state (MCH- dark, SP- light) and cycle number \- Column B + C: normalized volume average and standard deviation for Sample F2a \- Column D + E: normalized volume average and standard deviation for Sample G4a \- Column F + G: normalized volume average and standard deviation for Sample G5a \- Column H + I: normalized volume average and standard deviation for Sample Q1 \- Column J + K: normalized volume average and standard deviation for Sample Q2 \- Column L + M: normalized volume average and standard deviation for Sample Q3 \- Column N + O: normalized volume average and standard deviation for Sample O1 \- Column P + Q: normalized volume average and standard deviation for Sample O2 \- Column R + S: normalized volume average and standard deviation for Sample O3 \- Column T: normalized volume average for Sample R1 (silanized gel) \- Table 5: Batch Q bar chart (p(NIPAAm-co-AMPS-co-SP) hydrogels) (A64 - I72) \- row 65: sample identifier (internal use) \- Column A: light state (MCH- dark, SP- light) and cycle number \- Column B + C: normalized volume average and standard deviation for Sample Q1 \- Column D + E: normalized volume average and standard deviation for Sample Q2 \- Column F + G: normalized volume average and standard deviation for Sample Q3 \- Column H + I: normalized volume average and standard deviation for averages of Sample Q1 - Q3 \- Table 6: Batch O bar chart pNIPAAm (A74 - I78) \- row 75: sample identifier (internal use) \- Column A: light state (MCH- dark, SP- light) and cycle number \- Column B + C: normalized volume average and standard deviation for Sample O1 \- Column D + E: normalized volume average and standard deviation for Sample O2 \- Column F + G: normalized volume average and standard deviation for Sample O3 \- Column H + I: normalized volume average and standard deviation for averages of Sample O1 - O3 \- Table 7: Sample R1 bar chart (A80 - D83) \- row 81: cycle number \- Column A: light state (MCH- dark, SP- light) \- Column B: normalized volume average for cycle 1 \- Column C: normalized volume average for cycle 2 \- Column D: normalized volume average for cycle 3 \------------------------------------------------------------------------------------------- \############################################################################################# MATLAB Codes A) Tribometer_Indent_Analysis_v5 1\) natsortfiles B) Compiling_Friction_Data_v7 1\) natsortfiles ANALYZING TRIBOMETER INDENTATION DATA \------------------------------------------------------------------------------------------- A) Tribometer_Indent_Analysis_v5: opens microtribometer indentation data from Excel files and fits the data with the Hertz contact mechanics model using the lsqcurvefit function \------------------------------------------------------------------------------------------- ANALYZING TRIBOMETER FRICTION DATA \------------------------------------------------------------------------------------------- B) Compiling_Friction_Data_v7: opens microtribometer friction data from Excel files and calculates the friction coefficient from the specified x-range in the friction force loop over a specified number of cycles \------------------------------------------------------------------------------------------- FUNCTIONS TO DOWNLOAD \------------------------------------------------------------------------------------------- \- Author: Stephen Cobeldick \- Download from: https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort \- Citation: Stephen23 (2023). Natural-Order Filename Sort (https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort), MATLAB Central File Exchange. Retrieved 2021. \- Function of codes: reads and sorts through the files to analyze \- Functions: A) natsortfiles B) natsort \- Notes: natsortfiles calls natsort