Fig. 1. (a) Swelling behavior of the poly(DMAEMA-co-AA) hydrogels with time under different pH conditions. (b) pH dependence of the equilibrium swelling ratio (ESR) for the poly(DMAEMA-co-AA) hydrogels

Fig. 1. The reaction route to prepare the poly(DMAEMA-co-AA) hydrogels.

Fig. 2. Swelling kinetic in the poly(DMAEMA-co-AA) hydrogels under different pH conditions. The solid lines are the fitting curves with the expression of ln(SR) = ln\begin{document}$ K $\end{document}+\begin{document}$ n $\end{document}ln\begin{document}$ t $\end{document}

Fig. 3. Normalized FTIR spectra of CN stretching in the SCN^- anionic probe dissolved in the poly(DMAEMA-co-AA) hydrogels with different pH. The solid lines are the fitting curves using a pseudo-Voigt function [25, 38]. The background signal of poly(DMAEMA-co-AA) without the addition of SCN^- has been subtracted

Fig. 4. (a) Vibrational relaxation for the CN stretching of the SCN^- anionic probe in the poly(DMAEMA-co-AA) hydrogels under different pH conditions. The solid lines are the fitting curves using a biexponential decay function. (b) pH dependent vibrational lifetime constants of SCN^- probe in the poly(DMAEMA-co-AA) hydrogels

Fig. 5. (a) Rotational anisotropy decay of SCN^- anionic probe in the poly(DMAEMA-co-AA) hydrogels under different pH conditions. The solid lines are the fitting curves using a biexponential decay function. (b) pH dependence of the rotational time constants of the SCN^- probe in the poly(DMAEMA-co-AA) hydrogels.

Table 1. Swelling parameters of the poly(DMAEMA-co-AA) hydrogels under different pH conditions

Table 2. Rotational time constants of the SCN^- anion in the poly(DMAEMA-co-AA) hydrogels under different pH conditions