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Effect of intramolecular crosslinker properties on the mechanochemical fragmentation of covalently folded polymers

“…Polymer CL3-5, folded in TFE, was not included in this plot since a rate constant could not be obtained from plotting all the data obtained from sonications. Instead, this polymer, the only one with RV relatively similar to its linear precursor, exhibited a unique behavior, resembling those of folded polymers that have been sonicated in oil, 13 and polymers with very high M n . 8 Instead of observing a single rate of fragmentation, two rate constants can be extracted: during the first 45 min of the pulsed sonication, an initial slower rate constant (1.06 × 10 −6 min −1 ) was measured.…”

“…11,12 In recent studies, we demonstrated that SCPNs folded by covalent bonds, while thermoplastic in nature, respond to mechanical stress in a similar way to thermosets, presenting significantly higher rate of mechanochemistry, but demonstrating a significant slower loss in properties. 8,13 This effect depends on the molecule length, and becomes more pronounced in higher degrees of polymerization. 14 More recently, we have also shown that reversible noncovalent interactions used for intramolecular collapse present an additional advantage-due to entropic spring effects, these sacrificial bonds can reform after mechanical unfolding, leading to even longer property lifetimes.…”

“…There are numerous applications which depend on mechanical resiliency, such as structural materials as well as polymer additives such as viscosity modifiers. 13 Based on the initial fundamental results described above, 8,14 the models on the effect of shear on SCPNs 18,19 and the numerous options of CLs developed through the years 11 ; in this manuscript, we define the scientific basis for the role of the intramolecular CLs and their properties on the mechanochemical fragmentation of SCPNs; namely we study, for the first time, how intramolecular CL length, valency, positioning along the main chain, and mechanical strength affect the SCPN unique mechanical resiliency in solution by measuring how each of these parameters influence the mechanochemical fragmentation rate of the SCPNs. Importantly, these different physical and chemical parameters of the CL affect the SCPN structure (which can affect the transduction efficiency) as well as the rate of mechanochemistry, but the combination of results allows us to distinguish between the different effects.…”