Mortensen Kell, Annaka Masahiko
Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark.
Department of Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
ACS Macro Lett. 2018 Dec 18;7(12):1438-1442. doi: 10.1021/acsmacrolett.8b00792. Epub 2018 Nov 21.
Cross-linked Tetronic star block copolymer gels, based on poly(ethylene oxide) and poly(propylene oxide), behave quite regular with respect to mechanical properties, but exhibits unusual absence of structural response to strain. The elastic response is linear up to more than 100% strain, with a steady-state modulus of the order of 0.01 MPa after an initial stress relaxation. Neutron and X-ray scattering experiments show a consistent but unexpected response to uniaxial strain, with no changes in characteristic molecular dimensions. Upon strain beyond about 100%, that is, when the stress-strain curve is no longer linear, structural texture appears and becomes even more pronounced upon further strain, thus, indicating alignment of the self-assembled hexagonally ordered cylindrical micelles with the cylinder-axis perpendicular to the strain. It is proposed that the main structural response to large-amplitude strain is related to a layer-dominated structure of cross-linked star molecules.
基于聚环氧乙烷和聚环氧丙烷的交联四臂星型嵌段共聚物凝胶在力学性能方面表现出相当规则的特性，但对应变的结构响应却异常缺失。在超过100%应变之前，弹性响应呈线性，初始应力松弛后稳态模量约为0.01MPa。中子和X射线散射实验表明，对单轴应变的响应一致但出乎意料，特征分子尺寸没有变化。当应变超过约100%时，即应力-应变曲线不再呈线性时，结构纹理出现，并且在进一步应变时变得更加明显，这表明自组装六方有序圆柱形胶束的排列方向是圆柱轴垂直于应变方向。有人提出，对大幅度应变的主要结构响应与交联星型分子的层状主导结构有关。
