# Decoration of Polyfluorene-Wrapped Carbon Nanotubes with Photoleavable Side-Chains
## 2 Results and Discussion
### Polymer-SWNTs Dispersions and Characterization  
Having shown that cleavage of the side-chains is effective on the polymer in solution, we next investigated polymer-SWNTs complexes. Based on our previous work [64], direct dispersion of SWNTs using functionalized polyfluorene led to poorly dispersed samples. Therefore, PF-N\({}_{3}\) was functionalized post-dispersion. **PF-N\({}_{3}\)** and raw HiPco SWNTs (average tube diameter 0.8-1.2 nm) complexes were prepared following the procedures in the literature [60], Briefly, a mixture of 7.5 mg of **PF-N\({}_{3}\)** and 5 mg of SWNTs in 10 mL of THF was sonicated using a probe sonicator for 1 h. The resulting black suspension was centrifuged at 8346\(\times\)\(g\) for 30 min, and the supernatant was carefully removed to isolate the **PF-N\({}_{3}\)-SWNTs** dispersion. The side-chains were then introduced in situ by CuAAC following the procedures in the literature (Scheme 2) [60]. The reactions were monitored by IR spectroscopy via the disappearance of the polymer azide stretch at \(\sim\)2090 cm\({}^{-1}\) (Figure S6). Once the complete disappearance of the azide stretch was observed, the sample  
Figure 3: \({}^{1}\)H-NMR overlay of **PF-oNB-TEG** before irradiation (bottom), after 3 h of irradiation (middle) and after overnight irradiation (top) in CDCl3. was filtered through a Teflon membrane with 0.2 \(\upmu\)m pore diameter and thoroughly rinsed with THF until the filtrate did not fluoresce when excited with a hand-held UV lamp at 365 nm. The resulting thin films were then redispersed in 10 mL of THF. Characterization using UV-Vis--Near-Infrared (NIR) absorption spectroscopy was next performed (Figure 4). Each SWNTs species present within the polymer-SWNTs sample exhibits its own absorption signals. Three main regions are observed for HiPco SWNTs: two semiconducting regions, S\({}_{11}\) (830\(-\)1600 nm) and S\({}_{22}\) (600\(-\)800 nm), and one metallic region, M\({}_{11}\) (440\(-\)645 nm) [5]. The absorption spectra were normalized to the maximum absorption of the peak at 1140 nm to compare the different SWNTs' species. **PF-N\({}_{3}\)**-SWNTs and the post-click dispersions (**PF-TEG-SWNTs** and **PF-oNB-TEG-SWNTs**) show similar absorption features, suggesting a successful post-functionalization redesign. As shown in Figure 4, both m- and sc-SWNTs' species are present within the polymer-SWNTs complexes, suggesting a lack of selectivity for specific SWNTs' species under the dispersion conditions used. Figure 4: UV-Vis-NIR absorption spectra for **PF-SWNTs** (top), **PF-TEG-SWNTs** (middle) and **PF-oNB-TEG-SWNTs** (bottom). Spectra were normalized to the signal at 1140 cm\({}^{-1}\) and offset for clarity. To further characterize our polymer-SWNTs complexes, Raman spectroscopy was performed. In this technique, laser excitation wavelengths overlap with the Van Hove singularities present in the density of states for specific SWNTs' species [82]. Therefore, this technique allows examination of both m- and sc-SWNTs' species present in the polymer-SWNTs sample [83]. Since electronic transitions depend on SWNTs' diameter and type, multiple excitation wavelengths are needed to achieve full characterization [83]. The polymer-SWNTs samples for Raman spectroscopy were prepared by drop-casting the dispersion onto a silicon wafer, followed by evaporation at RT. A reference sample was prepared by sonicating raw SWNTs in chloroform and depositing on silicon using the same drop-casting method. For HiPco SWNTs, two excitation wavelengths were used: 633 and 785 nm. Using these wavelengths, both m- and sc-SWNTs are separately probed [84]. Figure 5 shows the radial breathing mode (RBM) for **PF-N\({}_{3}\)-SWNTs, PF-TEG-SWNTs,** and **PF-oNB-TEG-SWNTs** dispersions. The spectra were normalized to the G-band (-1590 cm\({}^{-1}\)) for comparative analysis. Using the 633 nm excitation wavelength, both m- (175\(-\)230 cm\({}^{-1}\)) and sc-SWNTs (240\(-\)300 cm\({}^{-1}\)) are in resonance and signals corresponding to both nanotube types are observed (Figure 5A) [85].