Connecting Pressure-Dependent Dynamics to Dynamics under Confinement: The Cooperative Free Volume Model Applied to Poly(4-chlorostyrene) Bulk and Thin Films
Connecting Pressure-Dependent Dynamics to Dynamics under Confinement: The Cooperative Free Volume Model Applied to Poly(4-chlorostyrene) Bulk and Thin Films
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DOI：
10.1021/acs.macromol.8b01392
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发表时间：
2018-10
期刊：
影响因子：
5.5
通讯作者：
Ronald P White;J. Lipson
中科院分区：
文献类型：
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作者：
Ronald P White;J. Lipson
我们应用我们的合作自由体积（CFV）速率模型的压力依赖性动力学描述的弛豫时间聚（4-氯苯乙烯）（P4 ClS）散装和薄膜。CFV模型将链段弛豫时间τ表示为温度T和热力学自由体积Vfree = V-Vhc的函数，其中极限硬核体积Vhc通过使用局部相关晶格（LCL）模型状态方程分析聚合物的实验PVT数据获得。在适应CFV来描述薄膜，我们假设的限制的主要影响是，该接口用于改变平均自由体积（平均密度）相比，散装。我们制定了一个简单的加权平均表达式（仅涉及单个界面相关参数）来描述薄膜的自由体积作为厚度h的函数，并在CFV模型表达式中使用此h相关的Vfree。仅使用P4 ClS体材料的环境压力弛豫时间数据，沿着PVT数据，我们对CFV模型进行了参数化。
We apply our cooperative free volume (CFV) rate model for pressure-dependent dynamics to describe the relaxation times for poly(4-chlorostyrene) (P4ClS) bulk and thin films. The CFV model expresses segmental relaxation times, τ, as a function of temperature, T, and thermodynamic free volume, Vfree = V – Vhc, where the limiting hard core volume, Vhc, is obtained via analysis of a polymer’s experimental PVT data using the locally correlated lattice (LCL) model equation of state. In adapting CFV to describe thin films, we assume that the main effect of confinement is that the interface serves to change the average free volume (average density) compared to bulk. We formulate a simple weighted average expression (involving just a single interface related parameter) to describe the free volume of a film as a function of thickness, h, and use this h-dependent Vfree within the CFV model expression. Using just ambient pressure relaxation time data on bulk P4ClS, along with PVT data, we parametrize the CFV model, w...