Physical gelation of supramolecular hydrogels cross-linked by metal-ligand interactions: Dynamic light scattering and microrheological studies
Physical gelation of supramolecular hydrogels cross-linked by metal-ligand interactions: Dynamic light scattering and microrheological studies
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DOI：
10.1016/j.polymer.2017.01.077
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发表时间：
2017-10
期刊：
影响因子：
4.6
通讯作者：
Hiroto Ozaki;T. Indei;T. Koga;T. Narita
中科院分区：
文献类型：
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作者：
Hiroto Ozaki;T. Indei;T. Koga;T. Narita
对含有咪唑基团的聚丙烯酰胺衍生物缔合聚合物溶液进行了基于扩散波谱、动态光散射 (DLS) 和宏观流变学的微观流变学分析。通过添加Ni离子，通过金属-配体键形成物理凝胶。物理凝胶点（瞬时网络渗透应该发生的地方）是通过微流变学确定的。在显示所有研究条件下遍历性的 DLS 测量中，我们观察到自相关函数的三种模式：快速、中间和慢速模式。快速模式是集体扩散（凝胶模式），而慢速模式则归因于簇的扩散。对于中间模式，随着镍离子浓度的增加，在微流变学确定的物理凝胶点附近观察到从扩散模式到弛豫模式的转变。在凝胶后状态中，中间模式可归因于宏观弛豫，因为活化能与宏观流变学估计的弛豫能相当。
Microrheology based on diffusing-wave spectroscopy, dynamic light scattering (DLS), and macrorheology were performed on solutions of polyacrylamide-derivative associating polymer containing imidazole groups. By adding Ni ion, the physical gel is formed by metal-ligand bond. The physical gel point, where the percolation of a transient network is supposed to occur, was microrheologically determined. In the DLS measurement showing ergodicity at all the conditions studied, we observed three modes in the autocorrelation functions: fast, intermediate, and slow modes. The fast mode is the collective diffusion (gel mode), while the slow mode is attributed to the diffusion of clusters. For the intermediate mode, with increase in Ni ion concentration, the transition from diffusive mode to relaxation mode was observed near the microrheologically determined physical gel point. In postgel regime, intermediate mode can be attributed to the macroscopic relaxation since the activation energies are comparable with the relaxation energy estimated by macrorheology.