4.7 Article

Tilting or Twisting? Using Anisotropic Solvent Diffusion in Polymeric Thermo-Responsive LLC Phases for the Distinction of Spatial Reorientation versus Inversion of the Helical Polymer Backbone

期刊

MACROMOLECULES
卷 56, 期 8, 页码 2947-2954

出版社

AMER CHEMICAL SOC
DOI: 10.1021/acs.macromol.2c02021

关键词

-

向作者/读者索取更多资源

We studied the temperature-dependent LLC behavior of helically chiral polypeptides, specifically PBPMLG and PBLA-co-PPLA. We observed a characteristic jump in the quadrupolar splittings Delta nu Q of the solvent's 2H signal during the transition of polymer rods from perpendicular to parallel orientation with respect to the magnetic field. By correlating Delta nu Q with the diffusion coefficients measured parallelly (D parallel to) and perpendicularly (D perpendicular to) to the magnetic field, we found a significant change in the D parallel to/D perpendicular to ratio at the transition temperature of the LLC phases.
We have recently investigated lyotropic liquid crystalline (LLC) phases from the class of helically chiral polypeptides, which exhibit temperature-dependent changes in their LLC behavior. Both poly-gamma-p-biphenylmethyl-L-glutamate (PBPMLG) and p oly-beta-(b enzyl )-co-(beta-phenethyl)-L-asp art ate (PBLA-co-PPLA) exhibit a transition at which the polymer rods rearrange from a perpendicular orientation to a parallel orientation with respect to the magnetic field. A characteristic jump of the quadrupolar splittings Delta nu Q of the solvent's 2H signal is observed in the deuterium spectra. In this work, we present NMR diffusometry in three spatial dimensions as a promising method to obtain information about the spatial arrangement of polymers in LLC phases by making use of the anisotropy of solvent translational diffusion. By correlating Delta nu Q with the diffusion coefficients measured parallelly (D parallel to) and perpendicularly (D perpendicular to) to the magnetic field, we find a significant change of the D parallel to/D perpendicular to ratio at the transition temperature of the LLC phases. This confirms previous results from experiments on deuterated polymers, which showed that a flipping of the alignment director with respect to the magnetic field is the process responsible for the observed transition.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.7
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据