Fig. 7: A boroxine-based hydrogel with high acid–base stability and reversible gel–sol transition.
From: Water-stable boroxine structure with dynamic covalent bonds
a Molecular structures of poly(PEGMEA-co-AMA-PBA) (1), poly(PEGMEA-co-AMA-(CH3O-PBA)) (2), and poly(PEGMEA-co-AMA-(HO-PBA)) (3). b Photos of 1, 2, and 3 in water, as well as 3 in acidic (pH=2) or alkaline (pH=10) solution, concentrations: 50 mg mL−1. c T2 distribution curves of 1 (black), 2 (red), and 3 (blue) in water at room temperature, recorded by LF–NMR, concentrations: 50 mg mL‒1. d Photos of 3 in the presence (triangle) and absence (circle) of HO-PBA trimer, as well as 3 in the presence of PBA (square) in a water–THF (v/v: 2:1) mixture. The molar ratios of PBA and HO-PBA trimer to HO-PBA fragments in 3 are approximately 3:1 and 1:1, respectively. e Illustration of the reversible gel–sol transition of 3 regulated by HO‑PBA trimer.
