域大小对局部玻璃过渡扰乱的长度尺度的影响 由于不可混合的玻璃-接口引起的局部玻璃过渡扰乱
Alexander A Couturier1, Connie B Roth1
1Department of Physics, Emory University, Atlanta, Georgia 30322, United States.
ACS macro letters
|August 18, 2025
概括
薄聚烯 (PS) 薄膜中的玻璃过渡温度 (Tg) 减少了附近的表面. 这项研究表明,聚合物接口和自由表面对封闭的PS膜中的Tg具有类似的影响.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学是一种材料科学.
- 物理化学 物理化学
背景情况:
- 聚合物的玻璃化过渡温度 (Tg) 对其机械和热性能至关重要.
- 表面和接口效应可以显著改变薄聚合物薄膜的Tg,这种现象被称为Tg抑郁.
研究的目的:
- 在封闭的聚烯 (PS) 薄膜中研究深度依赖的Tg配置 (Tg (z)) .
- 为了比较聚合物接口 (聚甲基酸/聚乙烯) 与PS薄膜Tg上的自由表面的影响.
- 了解域大小如何影响Tg梯度.
主要方法:
- 使用Pyrene光谱法测量了当地的Tg.
- 制备了玻璃状聚乙烯 (PS,75 nm) 的薄膜.
- 聚乙烯薄膜要么被聚乙烯基甲酸 (PnBMA,600 nm) 覆盖,要么暴露在一个空白的表面上.
- 一个中性基板限制了PS域大小.
主要成果:
- 无论是PNBMA/PS接口还是自由表面,都将PS薄膜的局部Tg降低了大约30K.
- 这种Tg减小从接口/表面延伸到距离接口/表面约30nm的深度.
- PnBMA/PS接口的干扰影响与这些受约束系统中自由表面的影响相当.
- 这与以前对不受约束,半无限系统的发现形成鲜明对比,其中接口效应扩展得更远.
结论:
- 总域大小对薄聚合物薄膜中的Tg梯度的大小和范围都有显著影响.
- 即使是薄的聚合物接口也可以对局部Tg产生强烈的影响,类似于自由表面,当聚合物领域足够有限时.
- 这些发现突出了限制和接口接近在确定近表面的聚合物动态的重要性.
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