玻璃过渡的动态和表面层的移动性在不纠的聚乙烯薄膜
Zhaohui Yang1, Yoshihisa Fujii, Fuk Kay Lee
1Department of Physics, Boston University, Boston, MA 02215, USA.
Science (New York, N.Y.)
|June 26, 2010
概括
聚合物薄膜的玻璃化过渡温度 (T ((g)) 随着薄膜厚度的减少而降低. 这种现象归因于移动的表面液层,它影响了薄膜中的聚合物流动.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
背景情况:
- 聚合物通常在其玻璃过渡温度 (T) 下固化为玻璃状无形状态.
- 关于薄膜厚度对聚合物T (g) 和底层机制的影响存在重大辩论.
- 了解这些厚度依赖的效应对于薄膜技术中的聚合物应用至关重要.
研究的目的:
- 为了研究聚合物薄膜厚度和玻璃过渡温度 (T ((g)) 之间的关系.
- 为了阐明观察到的变化T的起源 (g) 随着薄膜厚度的减少.
- 量化薄膜厚度对聚合物粘度和动态的影响.
主要方法:
- 在不同温度下对基板上的未纠的短链聚烯薄膜的粘度测量.
- 对温度依赖的粘度数据进行分析,以确定过渡温度.
- 应用水力动力学方程来模拟薄膜行为和表面效应.
主要成果:
- 随着聚合物薄膜厚度的下降,观察到粘度过渡温度的下降.
- 这种观察到的过渡温度变化与之前报告的聚合物薄膜玻璃过渡温度 (T ((g)) 的变化一致.
- 水力动力学建模表明,在研究的最薄薄膜中,高度移动的表面液层占主导地位.
结论:
- 该研究证实,聚合物T (g) 取决于薄膜厚度,较薄的薄膜呈现较低的过渡温度.
- 一个移动的表面液体层,呈现阿雷尼乌斯动态,被确定为薄聚合物薄膜中改变流动行为的主要原因.
- 这一表面层显著影响并可以主导纳米级聚合物薄膜的流动动力学.
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