Abstract:
The production of Schiff bases by the reversible condensation of primary amine and reactive carbonyl, such as aldehyde and ketone, is one of the most common reactions used for the construction of self-healing materials. It is desirable to develop self-healing conductive hydrogels with outstanding mechanical properties and satisfactory healing efficiency at the same time by integrating dynamic Schiff bases and hydrogen bonds. Here, a self-healing conductive hydrogel based on poly(acrylamide-
N-2-amino ethylacrylamide hydrochloride-
N-acryloyloxy succinimide)-BORAX/LiCl was synthesized from acrylamide (AM), N-2-aminoethyl acrylamide hydrochloride (AEAM) and N-acryloxysuccinimide (ASI) by the free-radical polymerization in a mixed solution of BORAX/LiCl. 2-Hydroxy-1-(4-(2-hydroxyethoxy)phenyl)-2-methyl-1-propanon (I2959) was used as photoinitiator under a UV irradiation of 284 nm. The conductive hydrogel is characteristic of two types of dynamic healing mechanisms base on Schiff bases and hydrogen bonds, endowing the hydrogel with excellent mechanical stability and strength. The chemical structure of N-2-aminoethyl acrylamide hydrochloride and N-acryloxysuccinimide was confirmed by
1H-NMR, and the formation of Schiff base in hydrogels was confirmed by Fourier infrared spectroscopy. The high elongation at break and self-healing efficiency of hydrogel were tested by the universal tension machine (a maximum elongation of up to 1495.2%, a strength of 328.9 kPa, and a strain healing efficiency of 56.1% within 48 h were determined). Electrochemical analysis demonstrated that the conductive hydrogel had an excellent electrical conductivity of 3.11 S/m.