Controlled Transport and Assembly of Soft Complex Matter

这项建议侧重于胶体-聚合物混合物在平衡和非平衡状态下的定向组装，这些体系在许多科学和工业应用中发挥着重要作用。例如，聚合物通常以低浓度加入以操纵胶体悬浮液，而固体纳米颗粒经常被用作填料以增强致密聚合物熔体和玻璃的性能。拟议的研究计划分为两个工作包(WPS)，分别关注两亲性聚合物-胶体混合物(WP1)的结构和流变学，以及聚合物接枝纳米粒子(WP2)系统的包装和传输。WP1：在过去的几十年里，人们进行了广泛的研究，以了解良好溶剂条件下二元胶体-聚合物混合物的平衡和流动特性，其中相互作用是纯排斥的，物理行为由熵效应主导。然而，许多实际系统在这两个物种的溶剂质量上存在轻微的不匹配，这已经足以在胶体和聚合物之间产生相当大的吸引力。与非热极限相比，这种情况要复杂得多，因为胶体和/或聚合物可以形成(可逆)聚集体。为了更好地理解这些复杂的体系，我们计划模拟静止和剪切状态下两亲性Janus球体和疏水或两亲性聚合物的混合物。吸附聚合物的加入可以显著影响自组装结构和对剪切的响应，因为聚合物能够在单个颗粒之间形成桥梁，从而延缓剪切诱导的团簇破裂。WP2：胶体-聚合物混合物的另一个有趣的表现是GNPs，其中软(有机)大分子附着在刚性(无机)NPs的表面。与传统的本体聚合物或传统的纳米复合材料相比，这些有效的单组分杂化材料可以改善材料的性能。块体材料的宏观响应特性强烈依赖于GNPs的微观结构特征。因此，我们计划开发理论模型和进行模拟，以更好地了解聚合物冠层的大小、形状和互穿程度如何取决于微观GNP属性，如接枝密度和接枝长度。此外，我们将研究自由聚合物和/或小分子通过刷子颗粒组件的聚合物基质的传输。

This proposal focuses on the directed assembly of colloid-polymer mixtures in and out of equilibrium, systems that play a significant role for many scientific and industrial applications. For example, polymers are routinely added in low concentrations to manipulate colloidal suspensions, while solid nanoparticles are often used as fillers to enhance the properties of dense polymer melts and glasses. The proposed research plan is divided into two work packages (WPs), which focus on the structure and rheology of amphiphilic polymer-colloid mixtures (WP1), and on the packaging and transport in polymer-grafted nanoparticle (GNP) systems (WP2).WP1: Over the past decades, extensive research was conducted to understand the equilibrium and flow properties of binary colloid-polymer mixtures under good solvent conditions, where the interactions are purely repulsive and the physical behavior is dominated by entropic effects. However, many real systems have a slight mismatch in solvent quality for the two species, which is already sufficient to cause a sizable attraction between the colloids and polymers. This situation is considerably more involved compared to the athermal limit, because the colloids and/or polymers can form (reversible) aggregates. To better understand these complex systems, we plan to simulate mixtures of amphiphilic Janus spheres and either hydrophobic or amphiphilic polymers at rest and under shear. The addition of adsorbing polymers could dramatically influence the self-assembled structures and the response to shear, as the polymers are able to form bridges between the individual particles and thus delay the shear-induced cluster breakup. WP2: Another intriguing manifestation of colloid-polymer mixtures are GNPs, where soft (organic) macromolecules are attached to the surface of rigid (inorganic) NPs. These effectively one-component hybrid materials allow for improved material properties compared to conventional bulk polymers or traditional nanocomposites. The macroscopic response characteristics of the bulk materials strongly depend on the microstructural features of the GNPs. Thus, we plan to develop theoretical models and perform simulations to better understand how the size, shape, and interpenetration of the polymer coronas depend on the microscopic GNP properties such as grafting density and graft length. Further, we will study the transport of free polymers and/or small molecules through the polymer matrix of the brush particle assemblies.