Roopnarine Brittany K, Adedeji Adediwura Deborah, Dhakal Sujata, Suresh Sneha, Morozova Svetlana
Department of Macromolecular Science and Engineering, Case Western Reserve University 2100 Adelbert Rd, Cleveland, Ohio 44106, United States.
ACS Polym Au. 2025 Mar 28;5(3):261-269. doi: 10.1021/acspolymersau.4c00099. eCollection 2025 Jun 11.
To determine the impact of the interface material properties on hydrodynamic interactions and transport, we have investigated how "soft" gel surfaces influence the local diffusion of polystyrene nanoparticles in deionized water in convex lens-induced confinement (CLiC). The gel coatings are created by polymerizing polyacrylamide onto glass surfaces, resulting in surfaces with varying moduli of 60, 1300, 2620, and 8400 Pa that are 30-100 nm in height. We analyze the diffusion using differential dynamic microscopy (DDM) as a function of proximity to the surface. We find that diffusion depends on the material properties of the surface. The gel layers are too thin to impact the hydrodynamic interactions experienced on the surface, mirroring the contact angle measurements. However, near softer, more hydrated layers, the nanoparticles can permeate into or between the gel surfaces. As the modulus increases, the partition into the gel is lower, and we observe absorption of the particles into the gel, but no discernible motion in the gel layers. No additional effects are observed as a function of the height of the surface coatings within the experimental range. We postulate that these findings contribute to understanding polymer dynamics at complex interfaces and can potentially lead to a transformative understanding of biofouling and polymer-based separations.
为了确定界面材料特性对流体动力相互作用和传输的影响，我们研究了“软”凝胶表面如何在凸透镜诱导限制（CLiC）条件下影响聚苯乙烯纳米颗粒在去离子水中的局部扩散。凝胶涂层是通过将聚丙烯酰胺聚合到玻璃表面形成的，得到了模量分别为60、1300、2620和8400 Pa且高度在30 - 100 nm的不同表面。我们使用差分动态显微镜（DDM）分析扩散情况，并将其作为与表面距离的函数。我们发现扩散取决于表面的材料特性。凝胶层太薄，无法影响表面上经历的流体动力相互作用，这与接触角测量结果一致。然而，在较软、水合程度更高的层附近，纳米颗粒可以渗透到凝胶表面内部或之间。随着模量的增加，进入凝胶的分配比例降低，并且我们观察到颗粒被吸收到凝胶中，但在凝胶层中没有可察觉的运动。在实验范围内，未观察到作为表面涂层高度函数的其他影响。我们推测这些发现有助于理解复杂界面处的聚合物动力学，并可能潜在地带来对生物污垢和基于聚合物的分离的变革性理解。
