论文标题
通过改变聚合物浓度来探测物理组装的凝胶系统的大变形和断裂行为
Probing Large Deformation and Fracture Behavior of Physically Assembled Gel System by Varying Polymer Concentration
论文作者
论文摘要
物理组装的凝胶由于其可调的机械性能而在许多领域都有希望的应用。在这里，我们报告了机械性能作为物理凝胶系统的聚合物体积分数（$ ϕ $）的函数，由矿物油中的聚（苯乙烯） - poly（异戊二烯）-poly（styrene）[PS-PI-PS]组成。 Pi-Block分子量高于纠缠分子量，这导致较高$ ϕ $的Pi-Blocks的纠缠。所有凝胶的胶束微观结构都会产生相似的应力松弛机制，这是由应力 - 释放结果的叠加所捕获的。拉伸测试实验揭示了纠缠凝胶的应变率依赖性响应。为了在$ ϕ $范围内捕获关键的能量释放速率（$γ_0$），进行了空化流变性和断裂实验，我们获得了$γ_0\ sim ϕ^{2.0} $。凝胶模量比例为$ ϕ^{2.39} $，其中指数可能由循环到桥分数的变化随增加$ ϕ $而决定。
Physically assembled gels have promising applications in many fields because of their tunable mechanical properties. Here, we report the mechanical properties as a function of polymer volume fraction ($ϕ$) for a physical gel system consists of poly(styrene)-poly(isoprene)-poly(styrene) [PS-PI-PS] in mineral oil. The PI-block molecular weight is higher than the entanglement molecular weight, which leads to the entanglement of PI-blocks at higher $ϕ$. The micellar microstructure for all gels results in a similar stress relaxation mechanism, as captured by the superposition of stress-relaxation results. Tensile testing experiments reveal a strain-rate dependence mechanical response for the entangled gels. To capture the critical energy release rate ($Γ_0$) over a range of $ϕ$, both cavitation rheology and fracture experiments were performed and we obtain $Γ_0\simϕ^{2.0}$. The gel moduli scale with the volume fraction as $ϕ^{2.39}$, where the exponent is likely dictated by the change in loop-to-bridge fraction with increasing $ϕ$.
