Polymer mechanochemistry

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Wiggins KM, Brantley JN, Bielawski CW (2012) Polymer mechanochemistry force enabled transformations. ACS Marco Lett 1 623... 

Larsen MB, Boydston AJ (2013) Flex-activated mechanophores using polymer mechanochemistry to direct bond bending activation. J Am Chem Soc 135 8189... 

Wang J, Kouznetsova TB, Kean ZS, Fan L, Mar BD, Martmez TJ, Craig SL (2014) A reanote stereochemical lever arm effect in polymer mechanochemistry. J Am Chem Soc 136 15162... 

Konda SSM, Brantley JN, Varghese BT, Wiggins KM, Bielawski CW, Makarov DE (2013) Molecular catch bonds and the anti-Hammond effect in polymer mechanochemistry. J Am Chem Soc 135 12722-12729... 

Keywords Bead-rod model Complex topology Mechanophore Polymer mechanochemistry... 

This review is organized on the basis of polymer architecture and highlights its effect on polymer mechanochemistry. The topic is restricted mostly to CST, chain degradation, and activation of mechanophores in dilute solution because more experimental and theoretical literature is available than that relating to the solid state. Solution or solid phenomena in which no CST or mechanochemical reaction occurs are therefore excluded. 

To make this review self-contained and to provide a foundatitMi for further discussion, we have included the experimental methods and theoretical models of mechanical degradation for linear chains in the second and third sections, respectively. From the fourth to seventh sections, the mechanochemistry of cyclic polymers, graft polymers, star-shaped polymers (star-shaped polymers), dendrimers, and hyperbranched polymers is summarized. In the eighth section, we survey the mechanochemistry of supramolecular aggregates and knotted polymers, where the topology constraints are temporal. We hope our overview can serve as a guideline for the future work in the field of polymer mechanochemistry. 

Design of mechanophore for nonlinear topologies. As we mentioned in the previous section, the development of polymer mechanochemistry in the last decade is largely promoted by the discovery of mechanophores. The current design of mechanophores in linear polymers is not perfect. We have proposed several adequate positions for mechanophores in nonlinear topologies. These designs are based on the computer simulations of CST and can be tested in the future. 

Brantley JN, Wiggins KM, Bielawski CW (2013) Polymer mechanochemistry the design and study of mechanophores. Polym Int 62 2-12... 

May PA, Moore JS (2013) Polymer mechanochemistry techniques to generate molecular force via elongational flows. Chem Soc Rev 42 7497-7506... 

Abstract The past 10 years have seen a resurgence of interest in the field of polymer mechanochemistry. Whilst the destructive effects of mechanical force on polymer chains have been known for decades, it was only recently that researchers tapped into these forces to realize more useful chemical transformations. The current review discusses the strategic incorporation of weak covalent bonds in polymers to create materials with stress-sensing and damage-repairing properties. Firstly, the development of mechanochromism and mechanoluminescence as stress reporters is considered. The second half focuses on the net formation of covalent bonds as a response to mechanical force, via mechanocatalysis and mechanically unmasked chemical reactivity, and concludes with perspectives for the field. 

Much of the work done in recent years on polymer mechanochemistry has made use of the high elongational strain rates observed around collapsing cavitation bubbles in sonicated solutions, as outlined in the section on mechanoluminescence [27]. In addition to the distinctive features of sonochemically-induced mechanical reactivity described above, further attention needs to be paid to the sonication conditions in the case of mechanochemical catalysis, because catalyst lifetime and turnover number are reduced by sonochemical byproducts. Implosion of cavitation bubbles is essentially an adiabatic process which leads to formation of local hotspots within the bubble in which temperature and pressure increases drastically. The content of cavitation bubbles pyrolyses under these extreme conditions and results in formation of reactive species, such as radicals and persistent secondary byproducts acidic byproducts may also form from the degradation of the substrates [75]. Chemical impurities deactivate the reactive catalyst partially if not completely. Recent studies in our group have shown that heat capacity of gas... 

To understand the current state of polymer mechanochemistry and to try to guess the directions of its evolution, it is useful to divide the phenomena studied by polymer mechanochemists (Fig. 1) into those where ... 

The vast majority of reported studies in polymer mechanochemistry are on linear polymers. Mechanochemistry of topologically complex polymers, which is of increasing industrial importance (see chapter Mechanochemistry of Topologically... 

The development of a general, quantitative conceptual framework which can guide the evolution of polymer mechanochemistry would revolutionize polymer... 

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