Mechanochemical and supramolecular self-healing polymers

目前的项目将通过封装原理结合两种自愈原理来解决自愈系统的产生，从而产生具有多个“自愈周期”的自愈聚合物。填充多价叠氮化物/炔-聚合物的胶囊将形成“一次愈合周期”系统，而第二（超分子）愈合系统将形成材料内部多次愈合周期的基础。后一种原理将基于两种氢键系统，一种具有较长的结合/解离寿命（汉密尔顿受体/巴比妥酸），另一种具有较短的结合/解离寿命（2,6-二氨基三嗪/胸腺嘧啶）。这两种治疗原理都将依赖于在其链端具有多个（反应性或缔合性）功能部分的液体聚合物。因此，多臂星形、枝晶和接枝聚合物将被用作封装（聚合物）试剂，其玻璃化转变温度（Tg）显著低于室温，以保持其在室温及以下的液体流动行为。两种主要的聚合物被预测用于此目的：(a)聚异丁烯（Tg ~（-70℃））和(b)（氧）降冰片烯与丁二烯的共聚物（Tg ~（- 90℃））。为了增加交联密度，从而提高“愈合”材料的最终机械强度，需要所有相互作用或反应基团的多价性。提出的概念将扩展到基于多价（炔）轴承聚合物和“荧光”染料的裂缝形成可视化，这将允许通过共聚焦激光显微镜（视觉）检测机械裂缝形成的位置。

The current project will address the generation of a self-healing system by combination of two principles of self-healing via encapsulation principles, thus generating self-healing polymers with more than one “self-healing-cycle”. Capsules filled with either a multivalent azide/alkyne-polymer will form the "one-healing-cycle" system, whereas a second (supramolecular) healing system will form the basis for multiple healing cycles within the material. The latter principle will be based on two hydrogen bonding systems, one with a relatively long lifetime of association/dissociation (Hamilton-receptor/barbituric acid), the other displaying a short lifetime of association/dissociation (2,6-diaminotriazine/thymine). Both healing principles will rely on liquid polymers bearing multiple (reactive or associative) functional moieties on their chain-ends. Thus multiarm-star-, dendritic- and graft-polymers will be used as encapsulated (polymeric) reagents, with a glass transition-temperature (Tg) significantly below room temperature, so as to retain their liquid flow behavior at room temperature and below. Two main polymers are projected to this purpose: (a) polyisobutylenes (Tg ~ (-70°C)) and (b) copolymers of (oxy)norbornenes with butadiene (Tg ~ (- 90 °C)). Multivalency of all interacting or reactive groups is needed in order to increase the crosslinking density and thus the final mechanical strength of the "healed" material. The presented concept will be extended towards the visualization of crack-formation based on multivalent (alkyne) bearing-polymer and "fluorogenic" dyes that will allow the (visual) detection of the position of mechanical crack-formation via confocal laser microscopy.