We report irreversible, shear-activated gelation in liquid crystalline solutions of a rigid polyelectrolyte that forms rodlike assemblies (rods) in salt-free solution. At rest, the liquid crystalline solutions are kinetically stable against gelation and exhibit low viscosities. Under steady shear at, or above, a critical shear rate, a physically cross-linked, nematic gel network forms due to linear growth and branching of the rods. Above a critical shear rate, the time scale of gelation can be tuned from hours to nearly instantaneously by varying the shear rate and solution concentration. The shear-activated gels are distinct in their structure and rheological properties from thermoreversible gels. At a fixed concentration, the induction time prior to gelation decreases exponentially with the shear rate. This result indicates that shear-activated thermalization of the electrostatically stabilized rods overcomes the energy barrier for rod–rod contact, enabling rod fusion and subsequent irreversible network formation.

中文翻译：

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液晶聚电解质的不可逆剪切活化凝胶化

我们报告了在无盐溶液中形成棒状组件（棒）的刚性聚电解质液晶溶液中不可逆的剪切活化凝胶化。在静止时，液晶溶液对凝胶化具有动力学稳定性并表现出低粘度。在临界剪切速率或高于临界剪切速率的稳定剪切下，由于棒的线性生长和分支，形成物理交联的向列凝胶网络。在临界剪切速率之上，通过改变剪切速率和溶液浓度，可以将凝胶化的时间尺度从几小时调整到几乎瞬间。剪切活化凝胶的结构和流变特性与热可逆凝胶不同。在固定浓度下，凝胶化前的诱导时间随剪切速率呈指数下降。