Université de Paris, Laboratoire Matière et Systèmes Complexes, CNRS, UMR 7057 , 10 rue A. Domon et L. Duquet , F-75013 Paris , France.
Université de Paris, ITODYS, CNRS, UMR 7086 , 15 rue J-A de Baïf , F-75013 Paris , France.
J Phys Chem B. 2020 Feb 6;124(5):900-908. doi: 10.1021/acs.jpcb.9b09590. Epub 2020 Jan 29.
We studied the assembly of nanoparticles (NPs) with oppositely charged linear and periodic copolymers (CPs), alternating ionic and polar sequences, in the dilute range of polymer concentration. For the first time, we considered CPs displaying a contour length much higher than the gold NP (AuNP) perimeter. We assumed that such CPs will enable the collection of a finite number of NPs into linear nanostructures with a gain of colloidal stability and a better structural control compared to electrostatic complexes obtained with homopolyelectrolytes. As a case study, we synthesized anionic AuNPs and CPs consisting of alternated cationic poly-l-lysine (PLL) blocks and polar sequences of poly(ethylene glycol) (PEG). We showed that complexation of AuNPs with CPs is quite similar to that observed with homo PLL. In that respect, finite size nanometric clusters, of less than 30 NPs, are formed outside the electroneutrality domain and a fast phase separation occurs at the electroneutrality. Nevertheless, the presence of PEG blocks allowed us to highlight some specific effects. First, the global charge of the positively charged clusters was found to be always lower for CP-based clusters than for homo PLL with a dependence of the charge with the number and the mass of the PEG blocks. Second, in spite of this effect which should have promoted the formation of a dense structure, the fractal dimension characterizing the structure of the clusters in bulk was found to be always below 1.8. Finally, we showed that PEG blocks influence the interparticle distance by disfavoring plasmon delocalization when the clusters are dispersed in water and collapse around the NPs when the clusters are deposited on the substrate.
我们研究了带相反电荷的线性和周期性嵌段共聚物（CPs）在聚合物浓度稀的范围内对纳米颗粒（NPs）的组装。我们首次考虑了具有比金纳米颗粒（AuNP）周长长得多的轮廓长度的 CPs。我们假设，这样的 CPs 将能够将有限数量的 NPs 收集到具有胶体稳定性的线性纳米结构中，并且与使用均聚物电解质获得的静电复合物相比具有更好的结构控制。作为案例研究，我们合成了带负电荷的 AuNPs 和由交替的阳离子聚-l-赖氨酸（PLL）块和聚（乙二醇）（PEG）的极性序列组成的 CPs。我们表明，AuNPs 与 CPs 的络合与与 homo PLL 观察到的非常相似。在这方面，小于 30 NPs 的有限尺寸纳米级簇在电中性域之外形成，并且在电中性时快速发生相分离。然而，PEG 块的存在允许我们突出一些特定的效果。首先，发现基于 CP 的簇的正电荷簇的总电荷总是比基于 homo PLL 的簇低，电荷与 PEG 块的数量和质量有关。其次，尽管这种效应应该促进密集结构的形成，但在体相中大簇的结构特征的分形维数始终低于 1.8。最后，我们表明 PEG 块通过在分散在水中的簇中不有利于等离子体离域，并且当簇沉积在基底上时围绕 NPs 坍塌，从而影响粒子间距离。
