Molecular mechanism of shear-induced gelation of nanocolloid/polymer mixtures

2015 Fiscal Year Final Research Report

• Project/Area Number: 25410224
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Polymer/Textile materials
• Research Institution: Kyoto University
• Principal Investigator: Koga Tsuyoshi 京都大学, 工学(系)研究科(研究院), 教授 (80303866)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 流動誘起ゲル化 / 会合性高分子 / 分子動力学シミュレーション / シア・シックニング / コンホメーション転移 / レオロジー / ナノ粒子

Outline of Final Research Achievements

We study the shear-induced gelation of mixtures of nanoparticle and associating polymers by using a molecular dynamics simulation method and transient network theory. The steady shear viscosity obtained by the simulation exhibits strong shear thickening at moderate shear rates, and shear thinning at larger shear rates. By analyzing the simulation data, it is shown that strong shear-thickening is caused by the network formation induced by shear flow. The scenario of the shear-induced network formation is as follows. In the small shear-rate regime, polymer chains take compact conformations due to strong association with a few colloid particles, which suppress the network formation. In the shear-thickening regime, such associated structures are destroyed by shear flow, leading to expanded conformations of polymer chains. This conformational change promotes the intermolecular association of polymers bridging colloid particles, and as a result, the network formation is enhanced.

Free Research Field

高分子物理化学