Supporting Information. Localized Phase Separation of Thermoresponsive Polymers. Induced by Plasmonic Heating

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1 Supporting Information Localized Phase Separation of Thermoresponsive Polymers Induced by Plasmonic Heating Issei Aibara, Jun-ichi Chikazawa, Takayuki Uwada and Shuichi Hashimoto*, Department of Optical Science and Technology, University of Tokushima, 2-1 Minami-Josanjima, Tokushima , Japan. Department of Chemistry, Josai University, 1-1 Keyakidai, Sakado, Saitama , Japan. S1

2 S1. Particle image and the corresponding histogram. 1 nm Figure S1. (a) TEM image of spherical reshaped gold nanoparticles ±5nm counts diameter / nm Figure S1. (b) Size distribution of gold nanoparticles used for the experiments. S2

3 Figure S2. Brightfield images of PNIPAM droplets formed on a glass substrate (a) (b) (c) (d) (e) (f) (g) (h) Figure S2 Bright-field images of 2-nm-diameter Au NP supported on a glass substrate and submerged in.96% aqueous PNIPAM solution. (a) Before irradiation. (b-e) During illumination at 5.28 mw μm -2 for 3 s (b), 6 s (c), 12 s (d), 19 s (e). (f-h) after the laser illumination was stopped:.25 s (f),.5 s (g), 2 s (h). S3

4 S3. The diameter of a light scattering sphere as a function of illumination time. (a) (b) diameter / mm mw mm mw mm mw mm mw mm -2 diameter / mm mw mm mw mm mw mm mw mm time / s time / s Figure S3-1. Light scattering sphere diameter as a function of time from the start of laser illumination of a 1-nm-diameter Au NP supported on a glass substrate and submerged in.96% aqueous PNIPAM solution: (a) at low intensities and (b) at high intensities. In (a), initial and final diameters of Au NP is the same, while, in (b) appreciably larger diameters were obtained after illumination being stopped. Diameter / mm mw mm mw mm mw mm mw mm mw mm Time / s Figure S3-2. Light scattering sphere diameter as a function of time from the start of laser illumination of a 1-nm-diameter Au NP supported on a sapphire substrate and submerged in.96% aqueous PNIPAM solution at various intensities. S4

5 S4. Darkfield images of PVME formed on a glass substrate..5% PVME, laser: 2. mw µm 2 Before 1 s 1 s 12 s laser off: 2 s 8.% PVME, laser: 2. mw µm 2.5% PVME, laser: 6. mw µm 2 8.% PVME, laser: 6. mw µm 2 Figure S4. Darkfield light-scattering images representing time evolution starting from the excitation of a single 1-nm-diameter Au NP supported on a glass substrate submerged in aqueous PVME solution. S5

6 S5. Viscosity of aqueous PVME solution aqueous PVME 298 K Relative viscosity Concentration / wt % Figure S5. Viscosity of aqueous PVME solution as a function of concentration. S6

7 S6. FEM-based simulation of the LSPR scattering spectra for 1-nm-diameter Au NP core PNIPAM shell structure supported on a sapphire substrate. (a) (b) scattering cross section / m 2 7x1-14 6x1-14 5x1-14 4x1-14 3x1-14 2x1-14 1x1-14 FEM t = nm t = 2 nm t = 4 nm t = 6 nm t = 8 nm t = 1 nm scattering cross section / m 2 7x1-14 6x1-14 5x1-14 4x1-14 3x1-14 2x1-14 1x1-14 Mie t = nm t = 2 nm t = 4 nm t = 6 nm t = 8 nm t = 1 nm (c) wavelength / nm Wavelength / nm volume ratio / % shell thickness / nm Figure S6. (a) FEM-based simulation of the LSPR scattering spectra for 1-nm-diameter Au NP core PNIPAM shell (n=1.5) structure supported on a sapphire substrate (n= 1.77) and submerged in water (n=1.33). (b) LSPR scattering spectral simulation based on the Mie calculation for comparison with (a). A concentric spherical Au NP (1-nm-diameter) core PNIPAM shell structure (n=1.45) dispersed in water (n=1.33) was assumed with various thicknesses of the shell. (c) The ratio of inaccessible volume to accessible volume dependent on the shell thickness is calculated on the basis of simple geometric consideration. S7

8 S7. SEM images Au NP-PNIPAM core-shell structure. Figure S7-1. Effect of repeated irradiations with high and low power cycles: 5.3 mw µm 2 for 2 s and.88 or.18 mw µm 2 for 6 s, on the scattering peak shifts of a 1-nm-diameter Au NP supported on a sapphire substrate in.96% aqueous PNIPAM solution and the corresponding SEM images. Figure S7-2. Effect of repeated irradiation on the scattering peak shifts of a 1-nm-diameter Au NP supported on a sapphire substrate submerged in 4.% aqueous poly (vinyl pyrrolidone) solution. Only redshifts suggesting the accumulation of the polymer and no detachment at a lower intensity were observed. S8

9 S8. Possible phase diagrams for polymers showing LCST phase separation in aqueous solution. Figure S8. LCST type II phase separation behaviour. 1 T dem is the demixing temperature, T Θ is the theta temperature, and T BP is the temperature corresponding to the Berghmans point. 2 For both polymers, T g in their solid state is well above T dem. For this UCST type polymer, T g cannot be lower than T BP. At temperatures below T BP, the polymer is frozen in, and phase morphology is preserved. 3 For the LCST-type polymer shown, partial vitrification takes place at T BP < T < T g. 4 References: 1. Aseyev, V.; Tenhu, H.; Winnik, F. M. Adv. Polym. Sci. 211, 242, Arnauts, J.; Berghmans, H.; Polym Commun. 1987, 28, Callister, S.; Keller, A.; Hikmet, R. M. Makromol. Chem. Macromol. Symp. 199, 39, Van Durme, K.; Van Assche, G.; Van Mele, B. Macromolecules 24, 37, S9

10 S9. Movies Nominal 1-nm-diameter Au NPs were used. Movie 1 Substrate: glass, laser peak power density:.88 mw μm 2,.96% PNIPAM aq. soln. Movie 2 Substrate: glass, laser peak power density: 1.8 mw μm 2,.96% PNIPAM aq. soln. Movie 3 Substrate: glass, laser peak power density: 5.3 mw μm 2,.96% PNIPAM aq. soln. Movie 4 Substrate: sapphire, laser peak power density: 5.3 mw μm 2,.96% PNIPAM aq. Soln. Movie 5 Substrate: glass, laser peak power density: 3.5 mw μm 2,.96% PNIPAM aq. soln. S1