Bhadauriya Sonal, Wang Xiaoteng, Nallapaneni Asritha, Masud Ali, Wang Zongyu, Lee Jaejun, Bockstaller Michael R, Al-Enizi Abdullah M, Camp Charles H, Stafford Christopher M, Douglas Jack F, Karim Alamgir
Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States.
Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, United States.
Nano Lett. 2021 Feb 10;21(3):1274-1281. doi: 10.1021/acs.nanolett.0c02817. Epub 2021 Feb 1.
Surface-textured polymer nanocomposite (PNC) films are utilized in many device applications, and therefore understanding the relaxation behavior of such films is important. By extending an in situ wrinkle relaxation method, we observed that the thermal stability of wrinkled PNC films, both above and below the glass transition temperature (), is proportional to a film's nanoparticle (polymer grafted and bare) concentration, with a slope that changes sign at a compensation temperature () that is determined to be in the vicinity of the film's . This provides unambiguous confirmation of entropy-enthalpy compensation (EEC) as a general feature of PNC films, implying that the stability of PNC films changes from being enhanced to becoming diminished by simply passing through this characteristic temperature, a phenomenon having evident practical ramifications. We suggest EEC will also arise in films where residual stresses are associated with the film fabrication process, which is relevant to nanotech device applications.
表面纹理化的聚合物纳米复合材料（PNC）薄膜被用于许多器件应用中，因此了解此类薄膜的松弛行为很重要。通过扩展一种原位皱纹松弛方法，我们观察到，在玻璃化转变温度（）之上和之下，皱纹PNC薄膜的热稳定性与薄膜的纳米颗粒（聚合物接枝和裸露的）浓度成正比，其斜率在一个补偿温度（）处改变符号，该补偿温度被确定在薄膜的附近。这明确证实了熵 - 焓补偿（EEC）是PNC薄膜的一个普遍特征，这意味着PNC薄膜的稳定性通过简单地经过这个特征温度就会从增强变为减弱，这一现象具有明显的实际影响。我们认为，在与薄膜制造过程相关的存在残余应力的薄膜中也会出现EEC，这与纳米技术器件应用相关。
