Peihan Lyu, Zhaoyu Ding, Masao Doi* and Xingkun Man*,
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引用次数: 0
Abstract
A sheet of glassy polymers placed in a solvent shows swelling behaviors quite different from that of soft polymers (rubbers and gels). (1) Non-Fickian diffusion (called case II diffusion): As solvent permeates into the sample, a sharp front is created between the swollen part and the glassy part, and it moves toward the center at constant speed. (2) Nonmonotonous swelling: The thickness of the sample first increases and then decreases toward the equilibrium value. Here we propose a theory to explain such anomalous behavior by extending the previous theory for swelling of soft gels. We regard the material as a continuum mixture of a glassy polymer network and solvent. We assume that the polymer network is a viscoelastic gel of glassy polymers, and its relaxation time depends strongly on solvent concentration. We show that this theory explains the above two characteristics of glassy polymers in a simple and unified framework. The theory predicts how the permeation speed of the solvent and the characteristic times of the swelling process depend on material parameters and experimental conditions, which can be checked experimentally.
将玻璃状聚合物薄片置于溶剂中,其膨胀行为与软聚合物(橡胶和凝胶)的膨胀行为截然不同。(1) 非费克式扩散(称为情况 II 扩散):当溶剂渗入样品时,在膨胀部分和玻璃状部分之间会形成一个锋面,并以恒定的速度向中心移动。(2) 非单调膨胀:样品的厚度先是增加,然后向平衡值减小。在此,我们通过扩展之前的软凝胶膨胀理论,提出一种理论来解释这种反常行为。我们将材料视为玻璃态聚合物网络和溶剂的连续混合物。我们假设聚合物网络是玻璃态聚合物的粘弹性凝胶,其弛豫时间与溶剂浓度密切相关。我们的研究表明,这一理论可以在一个简单而统一的框架内解释玻璃态聚合物的上述两个特性。该理论预测了溶剂的渗透速度和溶胀过程的特征时间如何依赖于材料参数和实验条件,这些都可以通过实验来验证。
期刊介绍:
ACS Macro Letters publishes research in all areas of contemporary soft matter science in which macromolecules play a key role, including nanotechnology, self-assembly, supramolecular chemistry, biomaterials, energy generation and storage, and renewable/sustainable materials. Submissions to ACS Macro Letters should justify clearly the rapid disclosure of the key elements of the study. The scope of the journal includes high-impact research of broad interest in all areas of polymer science and engineering, including cross-disciplinary research that interfaces with polymer science.
With the launch of ACS Macro Letters, all Communications that were formerly published in Macromolecules and Biomacromolecules will be published as Letters in ACS Macro Letters.