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Entropy-Enhanced Mechanochemical Activation for Thermal Degrafting of Surface-Tethered Dry Polystyrene Brushes
ACS Macro Letters ( IF 5.1 ) Pub Date : 2022-08-03 , DOI: 10.1021/acsmacrolett.2c00263
Fengliang Wang 1 , Wenqing Liu 1 , Rongxing Lu 1 , Jian-Hua Huang 1 , Biao Zuo 1 , Xinping Wang 1
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Dry polymer brushes have attracted great attention because of their potential utility in regulating interface properties. However, it is still unknown whether dry polymer brushes will exhibit degrafting behavior as a result of thermal annealing. Herein, a study of the conformational entropy effect on thermal degrafting of dry polystyrene (PS) brushes is presented. For PS brushes with an initial grafting density (σpini) of 0.61 nm–2, degrafting behavior was observed at 393 K, and the equilibrium σp was approximately 0.14 nm–2 at 413 K. However, for brushes with σpini ≤ 0.14 nm–2, thermal degrafting was not observed even if the temperature was increased to 453 K. Furthermore, we found that the degrafting rate was faster for PS brushes with higher σpini and higher molecular weights when σpini > 0.14 nm–2. Our findings confirmed that degrafting is a mechanochemical activation process driven by tension imposed on bonds that anchor the chains to the surface, and the process is amplified by conformational entropy.

中文翻译:

熵增强机械化学活化用于表面连接干式聚苯乙烯刷的热脱枝

干聚合物刷因其在调节界面性能方面的潜在用途而引起了极大的关注。然而,仍然未知干聚合物刷是否会因热退火而表现出脱接行为。本文研究了构象熵对干聚苯乙烯 (PS) 刷子热脱枝的影响。对于初始接枝密度 (σ p ini ) 为 0.61 nm –2的 PS 刷,在 393 K 时观察到脱接行为,在 413 K 时平衡 σ p约为 0.14 nm –2。然而,对于具有 σ pini的刷子≤ 0.14 纳米–2,即使温度升高到 453 K,也没有观察到热脱接。此外,我们发现当 σ pini > 0.14 nm –2 时,具有较高 σ pini 和较高分子量的PS速率更快。我们的研究结果证实,去接枝是一种机械化学活化过程,由施加在将链锚定到表面的键上的张力驱动,并且该过程被构象熵放大。
更新日期:2022-08-03
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