S2.3. Hydroxyl titration record of HBPSi-R
The concentration of hydroxyl group (-OH) was obtained according to a titrimetric method (GB/T 7383-2007, Chinese standard). Firstly, ~1.00 g of HBPSi-R was mixed with 25 ml phthalic anhydride pyridine solution (140.00 g to 1 L pyridine). The mixture was heating upon 115 oC for 60 min in a flask with condensing reflux. Then adding 4 ~ 5 drops of phenolphthalein indicator, the solution was titrated by 0.5 M sodium hydroxide solution (repeating 3 times) until the pink color maintaining more than 15 s. The control test was carried out for also 3 times without adding HBPSi-R. The Q(OH) can be calculated using Eqn (1).[6]
\begin{equation} Q_{(OH)}=\frac{c\times\left(V_{0}-V_{1}\right)}{m_{0}}\mathrm{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (1)}\nonumber \\ \end{equation}
Where c is the concentration of sodium hydroxide solution (0.50 mol·L-1); V0 andV1 are consumed volume of sodium hydroxide solution, respectively; m0 is the mass of HBPSi-R.
Table. S1 Titration experimental records for HBPSi-NH2, HBPSi-EP, HBPSi-V