Facile synthesis of novel elastomers with tunable dynamics for toughness, self-healing and adhesion

In this work, we develop a series of novel elastomers from acrylate monomers by one-step free radical copolymerization without using organic solvents. The dynamics of the elastomers, characterized by the Kuhn segment relaxation time (0), is tuned over six orders of magnitude by varying the structure and composition of the acrylate monomers. Comprehensive studies on linear rheology at small deformation and tensile/fracture behaviors at large deformation of the materials are performed. A universal ductile-brittle transition of the elastomers with the criterion of (0) similar or equal to 0.1 is observed for the diverse monomer pairs and stretch-strain rate and the elastomers exhibit maximum energy dissipation around the ductile-brittle transition reaching a work of extension at fracture of similar to 25 MJ m(-3) and a fracture energy of 20 kJ m(-2). Such toughness is comparable to that of natural rubbers and is among the highest ever reported. In addition, these elastomers possess 100% self-recovery, and a relatively high self-healing efficiency (37-70%) of the cut samples at room temperature even for relatively rigid samples and strong adhesive strength on glass and polymethylmethacrylate (PMMA) substrates. The universal ductile-brittle transition of the materials means that we can use the linear rheology dynamics as fingerprints for predicting the dynamic spectra of toughness of the materials. The wide range of tunable dynamics substantially enriches the choice of elastomers for various applications, and the facile and solvent-free synthesis of these elastomers is eco-friendly, cost-effective and scalable, which greatly lowers the barrier for practical applications.