Results and Discussion
The synthetic routes of monomers M1 and M3 are shown in Scheme S1 and the structures were characterized by1H NMR, 13C NMR, and high-resolution mass spectrometry analyses (Figure S1–S3, S5-S7). M2 could be directly by purchased and 1H NMR spectra was shown in Figure S4.
In previous work, we had shown that M1 could self-assemble in chloroform to form SPs.[20] To explore the process for adding small molecule M2 and M3 into theM1 solution (Figure 1a), the corresponding 1H NMR spectra of the M3 (Figure S8), and a mixture of M2 and M3 (Figure S9) at different time were recorded. As shown in Figure 1b, 0.1 equiv. of M3 were added to 50 mmol M1 . Due to the small amount addition of M3 , SPs were not crosslinked to a high enough degree and therefore formed a network rather than a gel. By comparing the 1H NMR spectra of the mixed solution at 2 h, 4 h, 8 h, 20 h, it could be determined that the reaction was essentially complete after 8 h. The peak of the aldehyde group of M3 at 10.05 ppm was significantly weakened, but the peak did not disappear completely. This was due to the fact that H2O was generated from the reaction of amine aldehyde condensation causing the hydrolysis of newly formed imine bond, thus leading to incomplete reaction.[21] In addition, a new peak appeared in the range of 8.20-8.28 ppm, which also proved that the imine bond were generated through the reaction between the amino groups at the ends of M1 and the aldehyde groups ofM3 .[22]