Dilute Solution Properties of Poly(benzyl methacrylate) in Ionic Liquids
Dilute Solution Properties of Poly(benzyl methacrylate) in Ionic Liquids
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DOI：
10.1021/acs.macromol.9b02618
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发表时间：
2020-02-11
期刊：
影响因子：
5.5
通讯作者：
Lodge, Timothy P.
中科院分区：
文献类型：
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作者：
Kharel, Aakriti;Hall, Cecilia;Lodge, Timothy P.
主要使用光散射技术，在四种不同的咪唑鎓基和吡咯烷鎓基离子液体中，在宽温度范围（27-155℃）下评估了一系列分子量（2 x 10(4) 至 1.6 x 10(5) g/mol）聚（甲基丙烯酸苄酯）的静态和动态特性。所有四个系统均表现出较低临界固溶温度相行为。研究了相关的结构、动态和热力学参数作为浓度、温度和分子量的函数。一些有趣的观察结果被揭示。相界表明临界组成向富含聚合物的区域移动，这与聚合物溶液中通常观察到的聚合物的低临界浓度相反。令人惊讶的是，即使在接近相分离的温度下，第二维里系数 (A(2)) 仍然为正，其中预计 A(2) < 0。此外，A(2) 还表现出比良溶剂中聚合物通常观察到的更强的分子量依赖性。在动态方面，扩散维里系数 (k(d)) 在给定温度范围内保持正值，进一步证实了 A(2) 的明显良好溶剂行为。从流体动力学半径对分子量的依赖性获得的排除体积指数（v 近似于 0.53-0.54）也表明了良好的溶剂特性。
The static and dynamic properties of a range of molecular weights (2 x 10(4) to 1.6 x 10(5) g/mol) of poly(benzyl methacrylate) have been assessed in four different imidazolium- and pyrrolidinium-based ionic liquids over a wide temperature range (27-155 degrees C), primarily using light scattering techniques. All four systems exhibit lower critical solution temperature phase behavior. The relevant structural, dynamic, and thermodynamic parameters were examined as a function of concentration, temperature, and molecular weight. Some interesting observations were revealed. The phase boundaries suggest a shift of the critical composition toward the polymer-rich region, in contrast to the low critical concentrations for polymers commonly observed in polymer solutions. Surprisingly, the second virial coefficient (A(2)) remains positive, even at temperatures close to phase separation, where A(2) < 0 is anticipated. Furthermore, A(2) also shows stronger dependence on molecular weight than commonly observed for polymers in good solvents. On the dynamic side, the diffusion virial coefficients (k(d)) remained positive over the given temperature range, further corroborating the apparent good solvent behavior of A(2). The excluded volume exponents (v approximate to 0.53-0.54) obtained from the dependence of hydrodynamic radii on molecular weight also indicate good solvent characteristics.