Reversible Thermal Stiffening in Polymer Nanocomposites

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• 作者：Erkan Senses ; Andrew Isherwood ; Pinar Akcora
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：July 15, 2015
• 年：2015
• 卷：7
• 期：27
• 页码：14682-14689
• 全文大小：568K
• ISSN：1944-8252

文摘

Miscible polymer blends with different glass transition temperatures (T_g) are known to create confined interphases between glassy and mobile chains. Here, we show that nanoparticles adsorbed with a high-T_g polymer, poly(methyl methacrylate), and dispersed in a low-T_g matrix polymer, poly(ethylene oxide), exhibit a liquid-to-solid transition at temperatures above T_g鈥檚 of both polymers. The mechanical adaptivity of nanocomposites to temperature underlies the existence of dynamically asymmetric bound layers on nanoparticles and more importantly reveals their impact on macroscopic mechanical response of composites. The unusual reversible stiffening behavior sets these materials apart from conventional polymer composites that soften upon heating. The presented stiffening mechanism in polymer nanocomposites can be used in applications for flexible electronics or mechanically induced actuators responding to environmental changes like temperature or magnetic fields.