Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, Brno 61200, Czech Republic.
Soft Matter. 2018 Mar 14;14(11):2094-2103. doi: 10.1039/c8sm00150b.
Polymer nanocomposites (PNCs) hold great promise as future lightweight functional materials processable by additive manufacturing technologies. However, their rapid deployment is hindered by their performance depending strongly on the nanoparticle (NP) spatial organization. Therefore, the ability to control nanoparticle dispersion in the process of PNC preparation is a crucial prerequisite for utilizing their potential in functional composites. We report on the bulk processing technique of tailored NP spatial organization in a model glass forming polymer matrix controlled by structural and kinetic variables of the preparation protocol. Namely, we studied the impact of solvent on the NP arrangement, which was already known as a tuning parameter of the solid-state structure. We emphasized the qualitative differences between "poorly dispersed" NP arrays, which, by combination of rheological assessment and structural analysis (TEM, USAXS), we identified as chain bound clusters and aggregates of either thermodynamic or kinetical origin. They are characterized by substantially distinct formation kinetics and mismatched properties compared to each other and individually dispersed NPs. We quantitatively linked all the currently observed types of NP dispersion with their rheological properties during the solution blending step and the amount of polymer adsorption and depletion attraction. We propose the ratio of NP-polymer and NP-solvent enthalpy of adsorption as a parameter capable of the quantitative prediction of NP arrangement in systems similar to our current model PNC. Finally, we bring forth the comparison of glass transition temperatures to further demonstrate the importance of NP spatial organization in PNCs.
聚合物纳米复合材料 (PNC) 有望成为未来可通过增材制造技术加工的轻量化功能材料。然而，其快速应用受到限制，因为其性能强烈依赖于纳米颗粒 (NP) 的空间组织。因此，在 PNC 制备过程中控制纳米颗粒分散的能力是充分发挥其在功能复合材料中潜力的关键前提。我们报告了在模型玻璃形成聚合物基体中通过结构和动力学变量控制的、具有定制 NP 空间组织的整体加工技术。也就是说，我们研究了溶剂对 NP 排列的影响，这已经是调节固态结构的参数之一。我们强调了“分散不良”NP 阵列之间的定性差异，通过流变评估和结构分析（TEM、USAXS），我们将其识别为链结合的簇和热力学或动力学起源的聚集体。它们的形成动力学和性能与彼此以及单独分散的 NPs 有很大不同。我们将所有目前观察到的 NP 分散类型与其在溶液混合步骤中的流变性能以及聚合物吸附和耗尽吸引力的量定量相关联。我们提出 NP-聚合物和 NP-溶剂吸附焓的比值作为能够定量预测类似于我们当前模型 PNC 的系统中 NP 排列的参数。最后，我们比较了玻璃化转变温度，以进一步证明 NP 空间组织在 PNC 中的重要性。
