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Determining Entanglement Molar Mass of Glassy Polyphenylenes Using Mechanochromic Molecular Springs
ACS Macro Letters ( IF 5.1 ) Pub Date : 2022-05-24 , DOI: 10.1021/acsmacrolett.2c00238
Maximilian Raisch 1 , Günter Reiter 2 , Michael Sommer 1
Affiliation  

Molecular force transduction in tough and glassy poly(meta,meta,para-phenylene) (PmmpP) was investigated as a function of Mn using covalently incorporated mechanochromic donor–acceptor torsional springs based on an ortho-substituted diphenyldiketopyrrolopyrrole (oDPP). Blending oDPP-PmmpP probe chains with long PmmpP matrix chains allowed us to investigate molar-mass-dependent mechanochromic properties for a series of specimens having mechanically identical properties. In the strain-hardening regime, the mechanochromic response (Δλmax,em) was found to be a linear function of the acting stress and fully reversible, making oDPP-PmmpP a real-time and quantitative stress sensor. For entangled and nonentangled probe chains, distinctly different values of Δλmax,em were observed, yielding a critical molar mass of Mc ≈ 11 kg mol–1 for PmmpP. Once physical cross-linking of oDPP in the network of PmmpP was ensured, Δλmax,em was found to be independent of Mn. The resulting value of Mc is in very good agreement with results from rheology.

中文翻译:

使用机械变色分子弹簧测定玻璃状聚苯的纠缠摩尔质量

使用基于邻位取代的二苯基二酮吡咯并吡咯 ( o DPP)的共价结合的机械变色供体-受体扭转弹簧,研究了坚韧和玻璃状聚(- 亚苯基) (P mmp P) 中的分子力传递与M n的函数关系. 将 DPP-P mmp P 探针链与长 P mmp P基质链混合,使我们能够研究一系列具有相同机械特性的样品的摩尔质量依赖性机械变色特性。在应变硬化状态下,机械变色响应 (Δλ max,em) 被发现是作用应力的线性函数并且完全可逆,使o DPP-P mmp P 成为实时和定量的应力传感器。对于纠缠和非纠缠的探针链,观察到明显不同的 Δλ max,em值,对于 P mmp P,产生M c ≈ 11 kg mol –1的临界摩尔质量。一旦o DPP 在 P 的网络中发生物理交联确保mmp P,发现 Δλ max,em与M n无关。所得的M c值与流变学的结果非常吻合。
更新日期:2022-05-24
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