Pre-Terminal Cross-Linked Polyisoprene: Mimicking Natural Rubber through a Multiple-Network Strategy for Outstanding Mechanical Performance

The synthesis of a high-performance synthetic polyisoprene (IR) that simultaneously matches the superior mechanical properties and processability (specifically, high green strength) of natural rubber (NR) has been a long-standing challenge. The key difficulty lies in replicating NR’s unique terminal network architecture that combines covalent and noncovalent interactions to enhance performance. This study addresses this challenge through a biomimetic strategy. Utilizing a “one-pot, sequential feeding coordination copolymerization” method, linear polyisoprene was reacted with the multicomponent epoxy monomer glycerol triglycidyl ether (GTE) at the polymer chain termini. This process prepared a preterminally cross-linked polyisoprene (PTCPI) with a biomimetic triple-network structure, comprising covalent cross-links, hydrogen bonds, and microphase separation. This strategy resolved the key scientific problem by artificially constructing a synergistic network within synthetic rubber. Consequently, the PTCPI material achieved outstanding performance, including a green strength of 2.64 MPa (10× PI, ∼70% higher than NR), superior tensile strength (30.5 MPa) and toughness (60.85 MJ/m 3 ) over both synthetic and natural rubber vulcanizates, and improved strain-induced crystallization kinetics, effectively matching or surpassing many of the benchmark properties set by NR.