Unraveling the molecular magic: AI explains the formation of the most stretchable hydrogel

Abstract

We synthesize a novel hydrogel with exceptional stretchability, capable of extending up to 260 times its original length. Its synthesis is guided by systematic optimization of key components: ammonium persulfate (APS), methylenebisacrylamide, dimethylacrylamide, and polyethylene oxide (PEO). We hypothesize that this extreme stretchability arises from a unique architecture—termed span networks—in which the primary dimethylacrylamide-based polymer network is cross-linked by methylenebisacrylamide and connected by linear PEO chains capable of undergoing random chain scission. Given the intractability of exhaustively analyzing all possible reaction pathways, we employ an AI-based reaction prediction system to investigate the underlying chemistry. This approach reveals a novel network formation mechanism involving PEO chains that link polymer networks through scission–prone interactions. These predicted mechanisms, including chain scission events between PEO and carboxyl groups, are experimentally validated using Fourier-transform infrared (FTIR) spectroscopy.