Colloidal Gelation through Thermally Triggered Surfactant Displacement
Colloidal Gelation through Thermally Triggered Surfactant Displacement
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DOI：
10.1021/acs.langmuir.9b00596
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发表时间：
2019-07-23
期刊：
影响因子：
3.9
通讯作者：
Doyle, Patrick S.
中科院分区：
文献类型：
--
作者：
Cheng, Li-Chiun;Sherman, Zachary M.;Doyle, Patrick S.
胶体体系的凝胶化过程在基础研究和实际应用中都引起了广泛的关注。合理调整粒子间的相互作用使研究人员能够精确地设计胶体材料的特性和微观结构。在这里，相反的传统方法，其中调制吸引力的相互作用是主要的焦点，我们提出了一个平台，其中胶体凝胶化是通过调整排斥相互作用控制。通过在胶体悬浮液中包括两亲性低聚物，胶体上的离子表面活性剂在升高的温度下被非离子低聚物表面活性剂取代，导致静电排斥的降低。该机制进行检查仔细表征的胶体，并随后允许构建粒子间电位捕捉材料的行为。随着热触发表面活性剂置换，分散体组装成大孔粘弹性网络，并且胶凝机制在宽范围的组合物、胶体尺寸和组分化学性质上是稳健的。这种刺激响应性凝胶化平台是通用的，并为设计复杂的粘弹性软材料提供了新的策略。
Colloidal systems that undergo gelation attract much attention in both fundamental studies and practical applications. Rational tuning of interparticle interactions allows researchers to precisely engineer colloidal material properties and microstructures. Here, contrary to the traditional approaches where modulating attractive interactions is the major focus, we present a platform wherein colloidal gelation is controlled by tuning repulsive interactions. By including amphiphilic oligomers in colloidal suspensions, the ionic surfactants on the colloids are replaced by the nonionic oligomer surfactants at elevated temperatures, leading to a decrease in electrostatic repulsion. The mechanism is examined by carefully characterizing the colloids, and subsequently allowing the construction of interparticle potentials to capture the material behaviors. With the thermally triggered surfactant displacement, the dispersion assembles into a macroporous viscoelastic network and the gelling mechanism is robust over a wide range of compositions, colloid sizes, and component chemistries. This stimulus-responsive gelation platform is general and offers new strategies to engineer complex viscoelastic soft materials.