Rheological and mechanical comparison of di-and tri-block copolymer imine vitrimers

Vitrimers' tendency to creep over time under stress poses a significant challenge to their widespread industrial use. Recently, nanoscale self-assembly has emerged as a promising route to control creep in vitrimers; however, mechanical robustness of such phase-separated materials requires further enhancement and investigation. Herein, we explored how the prepolymer architecture influences the structure-property relationships in vitrimers made of statistical copolymers, AB hard-soft diblock copolymers, and ABA hard-soft-hard triblock copolymers. Reversible addition fragmentation chain-transfer (RAFT) polymerization was employed to control the length, sequence, and morphology of the precursors. Dynamic imine functionalities were localized within the soft segment, which consisted of a bio-based copolymer of long-chain alkyl methacrylate and aldehyde-functional vanillin methacrylate. Compared to the statistical vitrimers, the triblock copolymer vitrimers exhibited approximately 60 % improved creep resistance, a 400 % increase in hardness, a higher tensile modulus, and ∼ 57 % higher stress at break. In contrast, vitrimers derived from diblock copolymers exhibited much weaker tensile properties with approximately 30 % lower stress at break. Our findings suggest that by controlling the chain architecture in block copolymers and optimizing the order–disorder transition, we can enhance vitrimers' creep resistance and tune their viscoelastic properties while tailoring their mechanical strength.