DOI: 10.17863/cam.118128
title: Research Data Supporting “Light-Driven Hexagonal-to-Cubic Phase Switching in Arylazopyrazole Lyotropic Liquid Crystals”

description: UV-Vis absorption spectra were taken using a Perkin Elmer Lambda 750 spectrometer with a slit width of 2 nm and a scan speed of 266.75 nm min-1. Measurements were taken at 1 nm intervals from 800 – 200 nm, using quartz cuvettes with a 10 mm path length. For Z-to-E isomerization measurements, 100 μL of hydrochloric acid (12 M) was added to 2 mL of AAP-PS (80 μM). Incomplete isomerization was observed immediately, with more significant change observable after 18 h storage in the dark. Note that effects from the cuvette led to a higher background in the Z-PSS sample, meaning a constant of 0.046 was subtracted from this trace to allow comparison with the other samples. Surface tension measurements were taken using a Krüss K100 force tensiometer (Krüss GmbH, Hamburg, Germany) in a 50 mL container, filled to a depth of 6 mm. Measurements were taken using a Du Noüy ring, at a speed of 3 mm min-1. Three measurements were taken for each sample and averaged, with errors given by the standard deviation. For Z-state measurements, the surface tensiometer was covered by a black cloth to avoid ambient light affecting the PSS. To determine the critical micelle concentration (CMC), plots of surface tension vs. concentration were fitted to two different straight lines, for the regions above and below the CMC. The CMC values were calculated from the intersection of these lines and error calculated using the standard error in the two straight-line regions. Zeta potential measurements were made using a Malvern Instruments Zetasizer. Micelle solutions of AAP-PS (20 mM) were prepared using triple-filtered water. ζ potential measurements were taken in the native, E state and the Z PSS, after irradiation for 4 hours using 365 nm light. Samples were equilibrated for 120 s at 25 °C, 3 measurements were taken with 60 s between each measurement. The 3 measurements were averaged, with the error given as the standard deviation. SAXS measurements were performed at the high-throughput SAXS beamline B21, Diamond Light Source (Oxfordshire, UK). The X-ray beam energy was 12.4 keV and detector distance set to 4.014 m, giving a q range of 0.0031 – 0.34 Å-1. For low-viscosity micellar samples (20-100 mM), samples were loaded into a 96-well PCR plate and stored at 25°C, before injection into a quartz capillary, held at 25°C, for measurement. All the samples were moved at 1 μL/s through the beam to avoid beam damage. 21 frames of 1 s exposure time were taken and the 2D diffraction patterns were radially averaged and integrated to get 1D data. The solvent background was subtracted using the ScÅtter software. Z-PSS samples were irradiated for 12 hours, with rotation every hour to ensure full isomerization. This was confirmed using UV-Vis absorption spectroscopy before measurement. The data were fitted using SASFit (version 0.94.11).4 The first 50 data points were removed and separate linear fits using OriginPro (2021b) were used to assess the aggregation 5 behaviour in this regime (q from 0.0045 up to 0.008 Å-1). A linear, horizontal background was set to an appropriate value. The data were fitted to ellipsoidal core-shell structures, with a Gaussian distribution around the polar radius to incorporate polydispersity into the model. Data were fitted to the polar radius, ellipsoidal radius, shell thickness and scattering length density. For higher concentration samples, a structure factor was also required to fit to the data. To achieve this, a Hayter-Penfold MSA model was fitted to the variables: hard-sphere radius, charge and volume fraction of micelles. For AAP-PS LLCs, samples were loaded into polyethylenimine (PEI) capillaries (low viscosity) or Kapton tape. Backgrounds of water in a PEI capillary or Kapton tape alone were subtracted using ScAtter and 20 frames of 1 s exposure time were averaged to give the final data pattern. Unless stated otherwise, samples were measured at 25 °C. For temperature ramp samples, the time needed to equilibrate the sample to the given temperature was measured using a thermocouple. The sample was then held at the temperature for the time measured before taking SAXS data. To measure isomerized LLCs, samples were irradiated in either a polyimide capillary (for 10- 30 wt% in water) or in a glass vial (50-90 wt%) for 3.5 hours. The irradiation time of 3.5 hours was chosen due to the high chromophore concentrations in the LLC phases, meaning that there is high absorbance of the UV irradiation and thus low penetration depth in the system. Furthermore, the high viscosity of the LLC phases limits diffusion of the isomerized surfactants. As such, 3.5 hours of irradiation was fixed to ensure that the surfactants formed Z-rich PSS. Samples in a capillary were transferred directly for SAXS measurements and samples in a vial were enclosed in Kapton tape before SAXS measurement. For LLC phase identification, OriginPro (2021b) was used to pick the peak positions. The ratio of the q values at the peak positions relative to the first peak (q0) were used to characterize the LLC phase present. POM micrographs were taken using a Leica EC4 camera fitted to an Olympus BHM microscope fitted with a polarizer and analyzer at 90° to each other. Samples were placed between two glass slides and pressed to ensure they were sufficiently thin for light transmission. Unless otherwise stated, samples were measured at room temperature. For the heating ramp, samples were heated using a Linkam PE120 Peltier heat stage controlled by a 6 T96 LinkPad controller and cooled using a water circulation pump. Samples were heated from 25-85 °C at a rate of 5 °C min-1. For the acid-induced reverse isomerization experiments, hydrochloric acid (12 M, 5 μL) was added to a slide containing AAP-PS LLC (90 wt%, 10 mg) that had been UV-irradiated to form the Z-PSS. The slide was left in the dark with periodic micrographs taken to track the selfassembly into the new LLC phase formed by the E isomer. Note that the addition of acid modifies the concentration of the LLC from 90 to 60 wt%, but both these concentrations are expected to form the same, HII phase at room temperature in the E isomer. To determine the percentage isomerization in AAP-PS-D2O LLCs, AAP-PS was mixed with D2O at 60 °C in concentrations from 10-90 wt%. To mimic the irradiation conditions from the SAXS study, 10-30 wt% samples were injected (30 μL) into a PEI capillary and 50-90 wt% samples were transferred to a small vial (50 mg). Samples were irradiated at 365 nm for 3.5 hours (as above). The samples were dissolved in DMSO-d6 (500 μL) and transferred to an NMR tube for measurement. Spectra were taken using a Bruker 400 MHz spectrometer, over 16 scans. Topspin 4.1.4 was used to calibrate to the solvent peak, pick peaks and perform peak integrations. For the membrane diffusion experiment, a solution of sodium carbonate (200 g L-1) was added to a round-bottom flask containing hydrochloric acid (2.4 M, 50 mL) at a steady rate of 1 mL min-1, using a syringe pump. Carbon dioxide formed during the reaction was fed into a Franz diffusion cell, which contained bicarbonate indicator (4 mL, 9:1 dilution) separated from the incoming gas by a hydrated, semi-permeable membrane (Spectra/Por® Biotech Dialysis Membrane, 20 kD). For diffusion studies, AAP-PS (90 wt%, ~50 mg) was loaded into a ring-shaped spacer (diameter = 20 mm, thickness = 1.5 mm) and sandwiched between two layers of semi-permeable membrane to form a thin layer. The experiment was run for a reference (with no LLC sandwiched between the semi-permeable membrane), an LLC that had been stored in the dark, and a separate sample of an LLC that had been irradiated with UV light for 3 hours. Once the carbon dioxide addition had started, the color of the bicarbonate indicator was monitored by eye, using video and using UV-Vis absorption spectroscopy after 0, 5.5 and 10 minutes of carbon dioxide addition. For the UV-Vis absorption measurements, a 500 μL aliquot of indicator was removed from the Franz cell and replaced with an equal volume of fresh 7 indicator. The aliquot was diluted in 1.5 mL of water and placed in a quartz cuvette for measurement.