Microscopic State of Polymer Network Chains upon Swelling and Deformation
Microscopic State of Polymer Network Chains upon Swelling and Deformation
复制标题
DOI：
10.1021/acs.macromol.9b00971
复制
发表时间：
2019-06
期刊：
影响因子：
5.5
通讯作者：
Anna Naumova;D. C. Agudelo;M. Villar;D. A. Vega;J. L. Valentín;K. Saalwächter
中科院分区：
文献类型：
--
作者：
Anna Naumova;D. C. Agudelo;M. Villar;D. A. Vega;J. L. Valentín;K. Saalwächter
我们使用低分辨率质子核磁共振在微观水平上探测膨胀和非线性变形的硫化橡胶和末端连接的PDMS网络中的链变形，将早期的工作重点扩展到膨胀时的单轴拉伸和各向同性膨胀，以及膨胀样品的双轴变形和变形。先前的研究表明，块状样品中的链变形最好用管模型来描述，膨胀样品中的链在初始的去分散阶段后会发生仿射变形，在这个阶段，缠结相关的堆积效应会得到缓解。我们测试了随后的变形是否也可能更接近仿射，并发现情况并非如此。出乎意料的是，膨胀样品的非各向同性变形也遵循管模型的预测，这是由结构不均匀性和在膨胀状态甚至可能是体状态中活跃的拓扑约束的显著重组所解释的。
We use low-resolution proton NMR to probe the chain deformation in swollen and nonlinearly deformed vulcanized rubber and end-linked PDMS networks on a microscopic level, extending earlier work focusing on uniaxial stretching and isotropic dilation upon swelling toward biaxial deformation and deformation of swollen samples. Previous studies have revealed that chain deformation in bulk samples is best described by tube models, and that chains in swollen samples deform affinely after an initial desinterspersion stage, upon which entanglement-related packing effects are relieved. We test whether a subsequent deformation may also be closer to affine, and find that this is not the case. Unexpectedly, nonisotropic deformation of swollen samples also follows tube-model predictions, which is explained by a dominance of structural inhomogeneities and significant reorganization of the topological constraints active in the swollen and possibly even the bulk state.