Anti-Arrhenius cleavage of covalent bonds in bottlebrush macromolecules on substrate

摘要: Abstract Spontaneous degradation of bottlebrush macromolecules on aqueous substrates was monitored by atomic force microscopy. Scission C─C covalent bonds in the brush backbone occurred due to steric repulsion between adsorbed side chains, which generated bond tension order several nano-Newtons. Unlike conventional chemical reactions, rate scission shown decrease with temperature. This apparent anti-Arrhenius behavior caused a surface energy underlying substrate upon heating, results corresponding macromolecules. Even though dropped minimally from 2.16 1.89 nN, this sufficient overpower increase thermal (kBT) Arrhenius equation. The constant bond-scission reaction measured as function temperature and energy. Fitting experimental data perturbed Morse potential V = V0(1 - e-βx)2 fx, we determined depth width be V0 141 ± 19 kJ/mol β-1 0.18 0.03 A, respectively. Whereas value is reasonable agreement activation Ea 80–220 mechanical organic polymers, it significantly lower than dissociation De 350 kJ/mol. Moreover, Kx 2β2V0 1.45 0.36 kN/m strained along its markedly larger Kl 0.44 kN/m, attributed additional stiffness deformation chains.