Supplementary Information Effect of Polymer Molecular Weight and Solution Parameters on Selective Dispersion of Single-Walled Carbon Nanotubes Florian Jakubka #, Stefan P. Schießl #, Sebastian Martin #, Jan M. Englert, Frank Hauke, Andreas Hirsch, and Jana Zaumseil # * # Institute of Polymer Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 7, 91058 Erlangen, Germany Institute of Advanced Materials and Processes (ZMP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Dr. Mack Str. 81, 90762 Fürth,Germany Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestraße 42, 91054 Erlangen, Germany S1 S2 S3 S4 S5 S6 S7 S8 Characterization of Polymer Source Material: Molecular Weight Distributions and 1 H- NMR Spectra of F8BT and PFO Polymers Characterization of Nanotube Source Material: HiPco Nanotubes Dispersed in D 2 O with Sodium Dodecyl Sulfate PL Excitation-Emission Spectra of SWNT-Polymer Dispersions and Normalized Selectivities Selectivity of (10,5) vs. (9,4) Nanotubes vs. Hansen and Hildebrand Solubility Parameters SWNT-Polymer Dispersion Absorbance Spectra with Different Solvents PL-Intensities of Nanotube Species in PFO with Different Solvents Influence of Polymer Concentration on Nanotube Dispersion Selectivity and Quantity Additional Solvent and Solution Viscosities 1
S1 Characterization of Polymer Source Materials: Molecular Weight Distributions and NMR Spectra of F8BT and PFO Polymers Figures S1a to S1c show the molar weight distributions of the used polymers determined by gel permeation chromatography (GPC). The polymers illustrated in the first two graphs were used for direct comparison of the degree of polymerization for F8BT (a) and PFO (b), while the F8BT polymers shown in (c) were used for solvent-dependent measurements (ADS, M W = 85 kg/mol) and variations of the polymer concentration (ADSn, M W = 153 kg/mol). For GPC Measurements, the polymers were dissolved in tetrahydrofuran at 1 mg/ml. A refraction index detector (Shodex, RI-101) recorded the size distribution in relation to the applied polystyrene standard (EasiCal, PS-1 polystyrene standards, M w = 580 7,500,000 g mol -1 ). For specific M W and polydispersity values see Table 1 and Table S8a. Figures S1d to S1h show 1 H-NMR-spectra of all used polymers. Measurements were performed on 400 MHz FT-NMR spectrometers (Jeol and Bruker) with the polymer dissolved in toluene-d 8 at a concentration of ~5 mg/ml. 1 H-NMR spectra show nearly identical peaks for all F8BT and PFO batches, respectively, and indicate no significant structural defects or differences. Protons of the fluorene and benzothiadiazole units are visible between 7.6 and 8.6 ppm in the aromatic low field region while aliphatic protons of the octyl chains resonate between 0.75 to 1.5 ppm at high fields. Polymers were end-capped with phenyl groups (CDT) or xylyl groups (ADS). Residual Pd and Ni catalyst amounts were in the ppm range and should not affect the structure of the polymer or dispersion selectivity. 2
Figure S1 3
Figure S1 (d) 4
Figure S1 (e) 5
Figure S1 (f) 6
Figure S1 (g) 7
Figure S1 (h) 8
S2 Characterization of Nanotube Source Material: HiPco Nanotubes Dispersed in D 2 O with Sodium Dodecyl Sulfate HiPco nanotubes from Unidym Inc. (Batch P0261) were dispersed at 1 mg/ml in D 2 O with sodium dodecyl sulfate as surfactant (1.26 wt%). Figure S2a shows the PL excitation-emission map of the sample with identified nanotube species (n,m). The corresponding graphene sheet shows the uncorrected (for PL efficiency) and normalized (versus (7,6) signal) distribution (see Figure S2b). Individual maximum PL-intensities of the detected nanotube species are presented in Table S2 together with specific excitation and emission wavelengths. Figure S2 (a) Figure S2 (b) 9
Table S2 Detected carbon nanotube species of the HiPco nanotube source with respective PL-intensities Chirality n,m Excitation Wavelength (nm) Emission Wavelength (nm) PL-intensity - backgroundcorrected (counts) 6,5 565 970 3397 7,5 645 1016 7525 7,6 645 1113 9577 8,3 665 943 4840 8,4 590 1106 6783 8,6 715 1166 5872 8,7 703 1260 3025 9,4 715 1097 9557 9,5 670 1239 3653 9,7 790 1320 1097 10,2 735 1047 6400 10,3 630 1244 3575 10,5 790 1249 2153 11,1 610 1254 2667 11,4 730 1260 3025 10
S3 PL Excitation-Emission Spectra of SWNT-Polymer Dispersions and Normalized Selectivities Figures S3a to S3d show PL maps of carbon nanotubes dispersed in F8BT and PFO together with the normalized semiconductor nanotube distribution compared to the source distribution in graphene sheets. The background-corrected PL intensities of all observed types of nanotubes are presented in Table S3a (F8BT) and Table S3b and S3c (PFO). All PL maps are scaled for maximum range. The absolute, background-corrected intensities vary between 1500 and 16000 counts for F8BT and from 1000 to 49000 counts for PFO. Maximum PL-values for the ADS polymer with toluene, o-xylene and mesitylene have been averaged over two samples. PLintensities and thus amount of individualized nanotubes tend to increase with molecular weight (also seen in the corresponding absorption spectra, Figure S5a). Medium M W PFO is the exception, showing a higher SWNT yield than the high M W PFO, which might be due to its high polydispersity (PD = 6.25) compared to the other polymers (PD = 1.78-3.86). Using empirical data by Weisman and Bachilo 1 and taking into account the usual emission redshift of several nm for polymer-wrapped nanotubes, most of the present peaks in the PL-sheets could be assigned to a specific chirality. Few phantom peaks usually correlate with FRETbased E 22 -E 11 transfer patterns between different nanotube species 2 and indicate either re-bundled nanotubes or closely grouped polymer-swnt complexes. The relative selectivity RS, illustrated in the graphene sheets, gives an overview of all detected nanotubes. RS was calculated by dividing the peak intensity of the individual nanotube by the respective nanotube intensities of the SDS reference sample (see Figure S2) and then normalizing to the maximum value. This way the specific nanotube selectivity of the solution can be extracted with minimal interference by the species distribution of the source material. 1. Weisman, R. B.; Bachilo, S. M. Nano Lett. 2003, 3, 1235-1238. 2. Lefebvre, J.; Finnie, P. J. Phys. Chem. C 2009, 113, 7536-7540. 11
Figure S3 (a) 12
Figure S3 (b) 13
Figure S3 (c) 14
Figure S3 (d) 15
Table S3 (a) Detected nanotube species with background-corrected PL-intensities for F8BT polymers Polymer F8BT low MW F8BT med. MW F8BT high MW F8BT low MW F8BT med. MW F8BT high MW Solvent Toluene Toluene Toluene o-xylene o-xylene o-xylene Chirality PL-intensity Chirality PL-intensity Polymer Solvent n,m (counts) n,m (counts) 8,7 806 8,7 1390 9,5 676 9,4 513 10,5 1390 9,5 1792 F8BT ADS Toluene 8,7 1438 10,3 699 9,4 904 10,5 4970 9,5 1886 11,1 667 10,3 1563 7,6 1383 10,5 4814 8,4 1831 7,6 1205 8,7 854 8,7 1204 F8BT ADS m-xylene 9,4 5063 9,4 3641 9,5 817 9,5 1413 10,5 2751 10,3 1133 11,1 663 10,5 3050 7,6 843 11,1 1245 8,4 1235 7,5 324 9,4 3598 F8BT ADS p-xylene 7,6 652 9,5 731 8,4 688 10,5 2154 8,6 352 11,1 601 8,7 873 7,5 722 9,4 1407 7,6 1597 9,5 989 8,4 3849 10,3 605 8,6 785 10,5 1297 F8BT ADS Mesitylene 8,7 1082 11,1 841 9,4 9570 7,6 2368 9,5 707 8,4 2632 10,5 2279 8,7 1446 11,1 1031 9,4 9228 7,6 3528 9,5 1879 8,4 4553 10,3 1573 8,7 1981 10,5 3485 9,4 11535 F8BT ADS o-xylene 11,1 1548 9,5 2132 7,6 7942 10,3 1134 8,4 13683 10,5 4705 8,7 2991 11,1 1192 9,4 28515 9,5 1790 10,3 1305 10,5 3711 11,1 2545 16
Table S3 (b) Detected nanotube species with background-corrected PL-intensities for PFO polymers Polymer Solvent Chirality n,m Intensity (counts) Polymer Solvent Chirality n,m Intensity (counts) PFO low MW Toluene PFO med. MW Toluene PFO high MW Toluene PFO low MW o-xylene PFO med. MW o-xylene PFO high MW o-xylene 7,5 610 7,5 106600 7,6 401 7,6 167600 8,6 516 8,4 39200 PFO med. 8,7 553 m-xylene 8,6 73600 MW 7,5 48370 8,7 42800 7,6 38730 9,4 38000 8,4 9648 10,3 22000 8,6 38034 7,5 55700 8,7 29009 7,6 46600 9,4 7680 8,4 10500 PFO med. 9,7 4206 p-xylene 8,6 23400 MW 11,1 7314 8,7 8700 7,5 16482 9,4 13080 7,6 14727 10,3 9900 8,4 3936 7,5 33700 8,6 17527 7,6 81000 8,7 9894 8,4 19800 PFO med. 9,4 3445 Mesitylene 8,6 40100 MW 9,7 2095 8,7 33300 11,1 2813 9,4 16480 7,5 6428 10,3 11610 7,6 1388 8,6 2323 8,7 862 7,5 40365 7,6 17533 8,4 2342 8,6 35663 8,7 10240 9,4 1939 7,5 19728 7,6 10858 8,4 3144 8,6 32955 8,7 3641 9,4 1976 17
S4 Selectivity of (10,5) vs. (9,4) Nanotubes vs. Hansen and Hildebrand Solubility Parameters Hildebrand and Hansen solubility parameters (Table S4) are widely used to estimate the solubility and interaction of different molecules and solvents with each other. The Hildebrand solubility parameter δ is the square root of the (total) cohesive energy density (E C /V) of the material: δ = V. The difference between the Hildebrand parameters of a solute (A) and a E C 2 solvent (B) determines the enthalpy of mixing: ( δ δ ) φ( 1 φ) H with φ being the volume fraction. Hansen solubility parameters are more complex with factors derived from dispersive (δ D ), dipole (δ P ) and hydrogen-bonding forces (δ H ). The correlation between Hansen and Hildebrand parameters is given by δ 2 = δ D 2 + δ P 2 + δ H 2. Figure S4 shows the selectivity S of (10,5) vs. (9,4) nanotubes (extracted from PL spectra in S3) in relation to the Hansen and Hildebrand parameters of various solvents. The dispersing polymer was medium molecular weight F8BT (ADS, M W = 85 kg/mol). mix A B Table S4: Hansen and Hildebrand parameters of the used solvents (from Hansen, C. M., Hansen Solubility Parameters - A Users Handbook 2 nd Edition. CRC Press: Boca Raton, Fl, USA, 2007). Solvent δ (MPa) 1/2 δ D (MPa) 1/2 δ P (MPa) 1/2 δ H (MPa) 1/2 Toluene 18.2 18.0 1.4 2.0 o-xylene 18.1 17.8 1.0 3.1 p-xylene 17.9 17.6 1.0 3.1 m-xylene 18.0 17.7 1.0 3.1 Mesitylene 18.5 18.0 0.0 0.6 Styrene 19.1 18.6 1.0 4.1 Ethylbenzene 17.9 17.8 0.6 1.4 18
Figure S4 19
S5 SWNT-Polymer Dispersion Absorption Spectra with Different Solvents Figures S5a and S5b show the absorption spectra of polymer-nanotube dispersions with different solvents (cuvette length 1 cm). The dispersing polymer is F8BT ADS with medium M W = 85 kg/mol in all cases. The different plots in Figure S5a focus on solvents that show distinct selectivity toward (10,5)-nanotubes (E 11 : 1275 nm), (9,4)-nanotubes (E 11 : 1122 nm) and (8,6)-nanotubes (E 11 : 1186 nm), while Figure S5b shows solvents that are rather unselective with no distinct preference for certain chiralities. An absorption spectrum of SDS-dispersed HiPco-SWNTs in D 2 O is shown as reference. Note, that the background was subtracted from all spectra to compare the relative peak heights. The graphs give an overview, which F8BT solutions disperse selectively and how much. Especially benzene and styrene show, similar to toluene, very good selectivity toward (10,5) nanotubes. Figure S5 (a) 20
Figure S5 (b) 21
S6 PL-Intensities of Nanotube Species in PFO with Different Solvents Figure S6 shows the PL intensities of individual nanotube species versus the kinematic viscosities of PFO solutions. The viscosity is varied by using different solvents while keeping polymer type molecular weight (M W = 90 kg/mol) and concentration constant. PL intensities were corrected by chirality-specific fluorescence action cross sections per number of carbon atoms (Φ) in the same way as for Figure 3 in the main text. Figure S6 22
S7 Influence of Polymer Concentration on Nanotube Dispersion Selectivity and Quantity Figures S7a to S7c show the influence of different F8BT polymer concentrations (ADSn, M W = 153 kg/mol) in toluene on selective nanotube dispersion. With increasing polymer content and thus viscosity not only the selectivity S [(10,5) vs. (9,4)] decreases from 0.91 to 0.66 (see Figure S7e), but also the total amount of nanotubes in the solution increases strongly, as shown in the corresponding absorption spectra in Figure S7d. For kinematic and dynamic viscosities, see Table S8a. Figure S7 23
S8 Additional Solvent and Solution Viscosities Table S8 (a) Viscosities of polymer solutions depending on solvent (constant concentration 2 mg/ml) and concentration Polymer Molecular Weight M w (g/mol) Polydispersity Solvent Density ρ (g/cm³) Kinematic Viscosity ν (mm²/s) Dynamic Viscosity η (mpa s) F8BT ADS 84,910 3.86 F8BT ADSn 2 mg/ml F8BT ADSn 5 mg/ml F8BT ADSn 10 mg/ml PFO medium MW 153,860 3.79 Toluene 90,300 6.25 Toluene 0.84 0.815 0.688 Mesitylene 0.83 0.955 0.793 o-xylene 0.82 1.057 0.873 m-xylene 0.82 0.836 0.686 p-xylene 0.82 0.865 0.715 0.86 0.924 0.795 0.88 1.591 1.400 0.90 3.310 2.979 m-xylene 0.84 0.822 0.690 p-xylene 0.84 0.872 0.739 Mesitylene 0.85 0.941 0.805 Table S8 (b) Viscosities of pure solvents Solvent Density (g/cm³) Kinematic Viscosity ν (mm 2 /s) Dynamic Viscosity η (mpa s) Toluene 0.86 0.657 0.568 o-xylene 0.87 0.886 0.779 m-xylene 0.86 0.692 0.600 p-xylene 0.86 0.715 0.616 Mesitylene 0.86 0.779 0.673 24