## 3 Results and Discussion  
### Polymerization of PNAMAm-p and the Deprotection Study  
The monomer NAMAMm-_p_ was synthesized via Mitsunobu reaction (Scheme 1a) and its molecular structure was confirmed by \({}^{1}\)H NMR (Figure S1a, Supplementary Material). Then the PNAMAm was prepared by traditional free radical polymerization of NAMAm-_p_ and one-step deprotection (Scheme 1b). Compared with the \({}^{1}\)H NMR spectrum of NAMAm-_p_, the PNAMAm-_p_ (Figure 1a) gives the peaks at 9.30, 5.17 and 7.84 ppm, which could be ascribed to secondary amine, methylene and phthalimide, respectively, while the peaks of the -CH=CH\({}_{2}\) protons (6.10 and 5.67 ppm) was not observed. The result confirmed the obtained PNAMAm-_p_ structure, and also, it well agreed with that found in the FT-IR spectra, wherein the stretching peaks of C=C at 1633 cm\({}^{-1}\) disappeared due to the polymerization of NAMAMm-_p_ monomer (Figure 1f-I, II).  
Deprotection of the PNAMAm-\(p\) was accomplished by hydrazine hydrate in DMF at room temperature for 2 h. As shown in Figure 1b, the phthalimide peak at 7.84 ppm disappears, the methylene peak shifts from 5.17 to 4.50 ppm, and a new peak is found at 5.90 ppm, which is attributed to the -O-NH\({}_{2}\) protons. The integral area ratio of peaks at 4.50 and 5.90 ppm is about 1:1, which is well consistent with the theory value. The results reveal that the PNAMAm-\(p\) is completely deprotected and the alkoxyamine groups are formed. Again, FT-IR spectra (Figure 1f) proved the deprotection due to disappearance of the stretching peaks of C=O at 1790 cm\({}^{-1}\), C=C at 1735 cm\({}^{-1}\). The high efficient deprotection ensures the precise control of functional group density on the polymers. According to GPC measurement (Figure 1d), the \(M_{\rm n}\) of PNAMAm-\(p\) is 3630 and the \(M_{\rm w}\) is 3940, the PDI is 1.36. A small difference in PDI (Figure 1d,e) was found, implying the molecular weight distribution of polymer chains did not change much in the deprotection process, and only the side groups were changed. However, the GPC results could not provide more information because the polymer polarity was greatly changed.  
We estiinated the reactivity of the side alkoxyamine groups by the model reaction. Acetone was used to react with PNAMAm to form oxime bonds. As shown in Figure 1c, the peak of -O-NH\({}_{2}\) protons at 5.90 ppm disappears, and the peak of methylene protons shifts from 4.50 to 4.90 ppm. This change is owing to the formation of oxime bonds. The product yield, which could be calculated by comparing the integration of the peak at 4.90 ppm, was about 95%. It means that the acetone is efficiently linked to the PNAMAm under the mild conditions. The results demonstrate that the  
Figure 1: \({}^{1}\)H NMR spectra of (**a**) PNAMAm-\(p\); (**b**) PNAMAm, and; (**c**) PNAMAm-m; GPC spectra of; (**d**) PNAMAm-\(p\) (PDI = 1.36), and; (**e**) PNAMAm (PDI = 1.37); (**f**) FT-IR spectra of (I) NAMAMm-\(p\); (II) PNAMAm-\(p\); and (III) PNAMA. The labelled peaks are (i) 1790 cm\({}^{-1}\); (ii) 1735 cm\({}^{-1}\) and (iii) 1633 cm\({}^{-1}\).  
PNAMAm not only possesses a high reaction activity, but also provides possibility for bioconjugation with aldehyde/ketone-based glycoproteins and glycopeptides in complex physiological environment.