Nanoparticle Aggregation Controlled by Desalting Kinetics
Nanoparticle Aggregation Controlled by Desalting Kinetics
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DOI：
10.1021/jp904665u
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发表时间：
2009-09-17
影响因子：
3.7
通讯作者：
Berret, J. -F.
中科院分区：
文献类型：
--
作者：
Fresnais, J.;Lavelle, C.;Berret, J. -F.
我们报告的形成稳定的纳米粒子的聚合物簇通过静电络合。置于仔细检查下的纳米氧化铈（CeO2）涂有短聚（丙烯酸）部分，而聚合物是阳离子中性嵌段共聚物。使用不同的配制途径监测簇形成，包括直接混合、透析、稀释和淬灭。在第一种方法中，通过混合聚合物和纳米颗粒的储备溶液获得杂化物。根据分子生物学开发的方法，透析和稀释基于受控的生物动力学。第四个过程由盐分散体的快速稀释组成，因此它被认为是簇动力学的淬灭。我们已经发现，控制静电簇形成动力学的一个关键参数是从溶液中除去盐的速率dI（s）/dt，其中Is表示离子强度。随着Is的减小，静电屏蔽的聚合物和纳米颗粒系统经历了一个突然的转变之间的非关联和聚集状态。通过调节反应动力学，团簇的尺寸从100 nm变化到1 μ m以上。在低离子强度，集群被发现是动力学冻结。据建议，聚集的发病是由聚合物的脱附-吸附到颗粒表面上的转变驱动的。
We report the formation of stable nanoparticle-polymer clusters obtained by electrostatic complexation. The nanoparticles placed under scrutiny were nanoceria (CeO2) coated with short poly(acrylic acid) moieties, whereas the polymers were cationic-neutral block copolymers. The cluster formation was monitored using different formulation pathways, including direct mixing, dialysis, dilution and quenching. In the first process, the hybrids were obtained by mixing stock solutions of polymers and nanoparticles. Dialysis and dilution were based on controlled desalting kinetics according to methods developed in moelcular biology. The fourth process consisted of a rapid dilution of the salted dispersions and as such it was regarded as a quench of the cluster kinetics. We have found that one key parameter that controlled the kinetics of formation of electrostatic clusters was the rate dI(s)/dt at which the salt was removed from the solution, where Is denotes the ionic strength. With decreasing Is, the electrostatically screened polymers and nanoparticles system underwent an abrupt transition between an unassociated and a clustered state. By tuning the desalting kinetics, the size of the clusters was varied from 100 nm to over 1 mu m. At low ionic strength, the clusters were found to be kinetically frozen. It is proposed that the onset of aggregation was driven by the desorption-adsorption transition of the polymers onto the surfaces of the particles.