Distinct interactions with pentaalanine tuned by terminal structures of polyisoprene that determine their mechanical properties

The terminal aggregates of natural rubber exhibit multi-scale reinforcing effects, but the synthetic counterpart still lacks of readily available terminal functionalized polymers, and the corresponding terminal structure-function correlation remains obscure. In this work, by utilizing commercial raw materials, four kinds of polyisoprene (PIP) derivatives with different terminal structures (PEO, ene-PEO, COOH, H) were prepared and blended with pentaalanine to investigated the change of terminal structures and impact on rubber performance. It is revealed that the tight hydrogen-bonded β-sheet in the terminal nanoconfinements is correlated to the overall performance of the elastomers. As the polarity of the terminal group of the main chain increases, the content of the β-sheet formed with 5A also increases, and the corresponding properties such as tensile strength, dimensional stability, strain recovery, apparent activation energy and cross-linking density are all enhanced. Among them, two elastomers (PIP-PEO, PIP-ene-PEO) have high tensile strength and great dimensional stability, which are comparable to Malaysian natural rubber. These results present the multi-scale reinforcement process of terminal H-bonding aggregates due to the synergistic changes and stable co-assembly of polar main chains and peptide, giving an inspiration for the development of large-scale, high strength and creep resistant synthetic elastomers. Four polyisoprene derivatives of different terminal structures are prepared from commercial raw materials and mixed with pentaalanine to form nanoaggregates, aiming to develop a way to harvest large-scale, high-strength and creep resistant synthetic rubbers, and establish the correlation between terminal structures and rubber performance. [Display omitted] •Polyisoprenes with different polar terminal groups were constructed.•Polar terminal groups and pentaalanine form stable assembly.•The stable terminal nanoconfinements dissipated stress and reorganize repeatedly.•Terminal H-bonding crosslinking determined the multi-scale strengthening effects.