Coil-to-Globule Transition in Polymeric Solvents
Coil-to-Globule Transition in Polymeric Solvents
复制标题
DOI：
10.1021/acs.macromol.1c01748
复制
发表时间：
2021-11
期刊：
影响因子：
5.5
通讯作者：
Yuci Xu;Zhen‐Gang Wang
中科院分区：
文献类型：
--
作者：
Yuci Xu;Zhen‐Gang Wang
我们使用自洽场理论研究了链长为 N1 的测试聚合物在链长为 N 的聚合物溶剂中的卷曲到球体 (C–G) 转变。对于短链溶剂，C-G 转变点由 (χN)tr–1/2 ∼ (pN)3/4N1–1/2 给出，与扩展的 Lifshitz 理论一致，其中 p=b2/vm2/3 是刚度参数。然而，对于长链溶剂，C-G 转变变成强一级转变，转变点由 (χN)tr–1/2 ∼pNN1–2/3 给出。标度分析表明，任何链长组合的转变点都是标度变量 x == (pN)3/2/N1 的通用函数，它可以清楚地解释为溶剂链的渗透体积与测试链的物理体积之间的比率，并且两种转变场景之间的交叉发生在 x∼ 1 处。此外，当正确无量纲化时，球体状态的密度分布以及转变时球体的中心密度和界面厚度也表现出通用行为。对于短链和长链溶剂情况，C-G 转变对应于球体界面厚度与核心尺寸相当的点。
We study the coil-to-globule (C–G) transition of a test polymer of chain lengthN1in a polymeric solvent of chain lengthNusing the self-consistent field theory. For short-chain solvents, the C–G transition point is given by (χN)tr–1/2 ∼ (pN)3/4N1–1/2, consistent with an extended Lifshitz theory, wherep=b2/vm2/3is the stiffness parameter. However, for long-chain solvents, the C–G transition becomes strongly first order, with the transition point given by (χN)tr–1/2 ∼pNN1–2/3. A scaling analysis suggests that the transition point for any chain length combination is a universal function of the scaling variablex≡ (pN)3/2/N1, which has the clear interpretation as the ratio between the pervaded volume of the solvent chain and the physical volume of the test chain and that a crossover between the two transition scenarios occurs atx∼ 1. Furthermore, when properly nondimensionalized, the density profile in the globule state and the center density and the interfacial thickness of the globule at the transition also exhibit universal behavior. For both the short-chain and long-chain solvent cases, the C–G transition corresponds to the point when the interfacial thickness of the globule becomes comparable to the core size.