The FTIR spectra of four phosphazenium salts and P5+ are shown in Figure S1. Four phosphazenium salts have characteristic absorptions at 2850 and 2930 cm-1, belonging to the stretching vibration of -CH2- and -CH-, respectively, and this peak in the P5+ represents the absorption of –CH3. All the five compounds exhibit absorption at 960, 1230, and 1442 cm-1 corresponding to the stretching vibrations of P–N. In the FTIR spectrum of Cy4P1+BF4-, the peaks at 1633 and 3432 cm-1 belong to water because of its strong hygroscopic nature.
In the 1H-NMR spectrum of Cy4P1+BF4- (Figure S2), δ = 2.95 and 2.63 ppm are attributed to the CH and CH3 protons; the peaks in the region δ =1.00–1.90 ppm are assignable to the CH2 protons in cyclohexane. The integrated areas of three protons indicate the presence of CH3 and cyclohexane groups. The single peak …show more content…
P5+ has a higher catalytic activity even with 0.5 wt% loading, and the Mn of PPO reached 4,080, 7,770, and 15,000 g/mol after 5, 13, and 28 h, respectively. The PDI of polyether from Pi4P1+ and P5+ was narrow in the range 1.027–1.036, but was higher (1.059–1.093) for Cy4P1+. Noteworthy, PPO catalyzed with Pi4P1+ displayed an extremely low unsaturation degree (0.004–0.008 mmol/g) and high average functionality (2.93–2.98).
In Table 2, the by-product, which has a great influence on the application of polyether, could not be identified. However, the GPC spectra in Figure 7 clearly show the composition of polyether, including the main polyether and other minor by-products. The GPC curves of PPOs obtained from Pi4P1+ and P5+ are smooth, and no other impurity peaks except the polyether main peak appeared; however, the GPC curves from Cy4P1+ have more impurity peaks, with two bumps appearing close to the main peak.
3.3 Analysis of the microstructure of
In the 1H-NMR spectrum of Cy4P1+BF4- (Figure S2), δ = 2.95 and 2.63 ppm are attributed to the CH and CH3 protons; the peaks in the region δ =1.00–1.90 ppm are assignable to the CH2 protons in cyclohexane. The integrated areas of three protons indicate the presence of CH3 and cyclohexane groups. The single peak …show more content…
P5+ has a higher catalytic activity even with 0.5 wt% loading, and the Mn of PPO reached 4,080, 7,770, and 15,000 g/mol after 5, 13, and 28 h, respectively. The PDI of polyether from Pi4P1+ and P5+ was narrow in the range 1.027–1.036, but was higher (1.059–1.093) for Cy4P1+. Noteworthy, PPO catalyzed with Pi4P1+ displayed an extremely low unsaturation degree (0.004–0.008 mmol/g) and high average functionality (2.93–2.98).
In Table 2, the by-product, which has a great influence on the application of polyether, could not be identified. However, the GPC spectra in Figure 7 clearly show the composition of polyether, including the main polyether and other minor by-products. The GPC curves of PPOs obtained from Pi4P1+ and P5+ are smooth, and no other impurity peaks except the polyether main peak appeared; however, the GPC curves from Cy4P1+ have more impurity peaks, with two bumps appearing close to the main peak.
3.3 Analysis of the microstructure of