Probing the causes of thermal hysteresis using tunable N agg micelles with linear and brush-like thermoresponsive coronas

Self-assembled thermoresponsive polymers in aqueous solution have great potential as smart, switchable materials for use in biomedical applications.


Representative polymer characterization data
1 H NMR and SEC data for the mCTA and the 50 mol% nBA diblock copolymer in each series is shown below Figure S2. 1 H NMR spectrum of mCTA1, analyzed at 400 MHz in CDCl 3 . Figure S3. 1 H NMR spectrum of polymer 1, analyzed at 400 MHz in CDCl 3 . Figure S4. SEC molecular weight distributions of mCTA1 and polymer 1, using 2% TEA in THF as the eluent and calibrated against PMMA standards. In each case, the distributions were calculated using the RI traces.

Figure S7
. SEC RI chromatograms of mCTA2 and polymer 6, using 5 mM NH 4 BF 4 in DMF as the eluent and calibrated against PMMA standards. In each case, the distributions were calculated using the RI traces.   Figure S10. SEC RI chromatograms of mCTA3 and polymer 11, using 2% TEA in THF as the eluent and calibrated against PMMA standards. In each case, the distributions were calculated using the RI traces.   Figure S13. SEC RI chromatograms of mCTA4 and polymer 17, using 2% TEA in THF as the eluent and calibrated against PMMA standards. In each case, the distributions were calculated using the RI traces. polymer 17 mCTA4 Figure S14. SEC RI chromatograms of polymer 17 before (black dashed line) and after (red solid line) three heating and cooling cycles from 50 -95 °C. 2% TEA in THF was used as the eluent and the instrument was calibrated against PMMA standards. In each case, the distributions were calculated using the RI traces. Representative light scattering data DLS and SLS data for the 100 mol% nBA diblock copolymer micelles in each series is shown below Figure S15. Multiple angle dynamic (above) and static (below) light scattering data of micelles comprised of polymer 5 at 1 mg mL -1 .

Representative turbidimetry data
Turbidimetry data for the 50 and 100 mol% nBA diblock copolymer micelles in each series is shown below.  Figure S20. Variable temperature turbidimetry analysis of micelles comprised of polymers 6 (above) and 10 (below) at 1 mg mL -1 . In each case, the solid trace represents the heating cycle and the dashed trace represents the cooling cycle.

Additional calculations and discussions
Calculation of core composition for polymers 1-5 Since the 1 H NMR peaks from mCTA1 overlapped with the peaks from the pnBA-co-DMA core-forming block of polymers 1-5, it was necessary to subtract the 1 H NMR spectrum of mCTA1 from each of the spectra obtained for polymers 1-5. This was achieved by normalizing the intensity of both spectra to a peak that remained unchanged by the chain extension, the signal at 3.44 ppm corresponding to the methylene protons in the macroCTA's side chain. Following subtraction, the integrals of the peaks at 4.00 and 3.22 -2.77 ppm, corresponding to pnBA and pDMA respectively, were used to determine the core composition using the known DP of mCTA1. Figure S24. 1 H NMR spectra of mCTA1 (top) and polymer 3 (middle). Below is the spectrum of mCTA1 subtracted from that of polymer 3 used to calculate the core composition; the peaks at 4.00 and 3.22 -2.77 ppm are clearly resolved.

Definitions and calculations regarding the light scattering data
The scattering wave vector, q, is defined in equation (1) where n is the refractive index of the solvent, λ is the wavelength of the incident beam and θ is the angle of measurement.
The constrast factor, K, is defined in equation (2) where n standard is the refractive index of the toluene standard, dn/dc is the refractive index increment of the sample, N A is Avogadro's number and λ is the wavelength of the incident beam.
The Rayleigh ratio of the sample, R θ , is defined in equation (3) where I sample , I solvent and I standard are the intensity of scattered light of the sample, solvent and standard respectively, detected for each angle of interest and R θ, standard is the Rayleigh ratio of the toluene standard.
R core was calculated from N agg using equation (4) where ρ is the composition-weighted density of the two monomers in the core-forming block and M w, core is the weight average molecular weight of the coreforming block, calculated by the number average molecular weight, M n , determined by 1 H NMR multiplied by Ð determined by SEC analysis.
The average chain density within micelles comprised of pDEGMA (11-15) were calculated using equation (

Discussion of the effect of chain density on reversibility for pDEGMA micelles
The chain density of the micelles with pDEGMA coronas (11-15) as calculated using equation (5) are plotted as a function of core composition in fig. S25. There are two clear regions, which correspond to micelles whose transitions were reversible and irreversible respectively. Figure S25. Chain density of micelles comprised of polymers 11-15. Error bars represent 10% error. The two distinct regimes of reversible and irreversible phase transitions are marked with dashed lines. Note that polymer 14 (88% nBA in the core forming block) shows the highest chain density because its R H is smaller than that of polymer 15 (100% nBA in the core forming block).