Rheological properties of phase transitions in polydisperse and monodisperse colloidal rod systems
Rheological properties of phase transitions in polydisperse and monodisperse colloidal rod systems
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DOI：
10.1002/aic.17401
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发表时间：
2021-08-25
期刊：
影响因子：
3.7
通讯作者：
Schultz, Kelly M.
中科院分区：
文献类型：
--
作者：
He, Shiqin;Pascucci, Dominic R.;Schultz, Kelly M.
流变改性剂添加到配方中以调节流变性，实现功能并驱动相变，需要了解材料结构和性能。我们表征两个胶体棒系统在相变过程中使用多粒子跟踪微观流变学，测量嵌入在样品中的探针的布朗运动。这些系统包括胶体（单分散聚酰胺或多分散氢化蓖麻油），表面活性剂（直链烷基苯磺酸盐[LAS]）和非吸收性聚合物（聚环氧乙烷[PEO]），其通过消耗相互作用驱动凝胶化。使用时间固化叠加在所有浓度下表征相变。我们确定流变演化取决于LAS：胶体。形成凝胶所需的临界PEO浓度c（c）/c* 与LAS：胶体无关，临界弛豫指数n与LAS：胶体有关，两者均与胶体多分散性无关。n表示相变时的材料结构。在LAS：胶体> 16时，支架是紧密缔合的网络，而在LAS：胶体= 16时，支架是松散缔合的网络。
Rheological modifiers are added to formulations to tune rheology, enable function and drive phase changes requiring an understanding of material structure and properties. We characterize two colloidal rod systems during phase transitions using multiple particle tracking microrheology, which measures the Brownian motion of probes embedded in a sample. These systems include a colloid (monodisperse polyamide or polydisperse hydrogenated castor oil), surfactant (linear alkylbenzene sulfonate [LAS]), and nonabsorbing polymer (polyethylene oxide [PEO]) which drives gelation by depletion interactions. Phase transitions are characterized at all concentrations using time-cure superposition. We determine that rheological evolution depends on LAS:colloid. The critical PEO concentration required to form a gel, c(c)/c*, is independent of LAS:colloid, critical relaxation exponent, n, is dependent on LAS:colloid, and both are independent of colloid polydispersity. n indicates the material structure at the phase transition. At LAS:colloid > 16, the scaffold is a tightly associated network and at LAS:colloid = 16 a loosely associated network.