Mechanochemical strengthening of a synthetic polymer in response to typically destructive shear forces.
Mechanochemical strengthening of a synthetic polymer in response to typically destructive shear forces.
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已知高剪切应力会引发聚合物中的破坏性断键反应。最近的工作表明，相同的剪切力可以用于加速沿沿着聚合物主链的机械载体中的非破坏性反应，并且这里证明了这种机械化学反应可以用于增强经受否则破坏性剪切力的聚合物。聚丁二烯官能化与二溴环丙烷机械，其机械活化生成烯丙基溴，通过亲核取代反应与羧酸酯原位交联。在溶剂化体系和本体材料中，通过剪切力有效地活化交联，并且所得的共价聚合物网络具有比未活化的聚合物大几个数量级的模量。这些分子水平的响应及其对聚合物性能的影响对材料的设计具有影响，这些材料与生物材料一样，根据其物理环境的功能在局部积极重塑。
High shear stresses are known to trigger destructive bond-scission reactions in polymers. Recent work has shown that the same shear forces can be used to accelerate non-destructive reactions in mechanophores along polymer backbones, and it is demonstrated here that such mechanochemical reactions can be used to strengthen a polymer subjected to otherwise destructive shear forces. Polybutadiene was functionalized with dibromocyclopropane mechanophores, whose mechanical activation generates allylic bromides that are crosslinked in situ by nucleophilic substitution reactions with carboxylates. The crosslinking is activated efficiently by shear forces both in solvated systems and in bulk materials, and the resulting covalent polymer networks possess moduli that are orders-of-magnitude greater than those of the unactivated polymers. These molecular-level responses and their impact on polymer properties have implications for the design of materials that, like biological materials, actively remodel locally as a function of their physical environment.
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