Experimental study of substrate roughness on the local glass transition of polystyrene
Experimental study of substrate roughness on the local glass transition of polystyrene
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DOI：
10.1063/5.0011380
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发表时间：
2020-06-28
影响因子：
4.4
通讯作者：
Roth, Connie B.
中科院分区：
文献类型：
--
作者：
Huang, Xinru;Thees, Michael F.;Roth, Connie B.
许多计算机模拟表明，与光滑界面相比，与玻璃化转变相关的局部动力学在粗糙界面附近可能较慢。尽管表面粗糙度的影响经常被认为是计算和理论上，几乎没有实验研究存在调查这些影响。使用氟化氢蒸汽处理，我们创造了二氧化硅衬底，粗糙度增加，表面化学性质不变。用荧光法测量了粗糙度增加的二氧化硅衬底附近的局部玻璃化转变温度T-g，发现随着均方根粗糙度R-rms从0.5 nm增加到11 nm，局部T-g增加了10 K。发现创建局部T-g的实验变化所需的衬底粗糙度的表征是相当大的，使得这种观察到的行为的机制不确定。我们讨论了可能的原因与聚合物链更容易能够使表面接触和吸附粗糙的界面。
Numerous computer simulations have shown that local dynamics associated with the glass transition can be slower next to rough interfaces compared with smooth interfaces. Even though the impact of surface roughness has been frequently considered computationally and theoretically, almost no experimental studies exist investigating these effects. Using a hydrogen fluoride vapor treatment, we created silica substrates with an increase in roughness that left the surface chemistry unchanged. The local glass transition temperature T-g near silica substrates with an increase in roughness was measured using fluorescence, finding an increase in local T-g of 10 K with an increase in the root-mean-square roughness R-rms from 0.5 nm to 11 nm. Characterization of the substrate roughness needed to create an experimental change in local T-g was found to be quite large, leaving the mechanism for this observed behavior uncertain. We discuss possible causes associated with polymer chains being more readily able to make surface contacts and adsorb to roughened interfaces.