pH-Controlled assembly of polyelectrolyte layers on silica nanoparticles in concentrated suspension
Artikel i vetenskaplig tidskrift, 2022

Hypothesis: Preparation of suspensions of nanoparticles (>1 wt%) coated with a polyelectrolyte multilayers is a challenging task because of the risk of flocculation when a polyelectrolyte is added to a suspension of oppositely charged nanoparticles. This situation can be avoided if the charge density of the polymers and particles is controlled during mixing so as to separate mixing and adsorption events. Experiments: The cationic polyethylenimine (PEI) and the anionic carboxymethylcellulose (CMC) were used as weak polyelectrolytes. Polyelectrolyte multilayers build-up was conducted by reducing the charge of one of the components during the addition of the next component. Charge density was controlled by tuning pH. Analysis of the suspension of coated nanoparticles was done by means of dynamic light scattering, electrophoresis and small angle x-ray scattering measurements, while quartz crystal microbalance was used to study the build-up process on flat silica surfaces. Findings: Charge density, controlled through pH, can be used as a tool to avoid flocculation during layer-by-layer deposition of polyelectrolytes on 20 nm silica particles at high concentration (∼40 wt%). When added to silica at pH 3, PEI did not induce flocculation. Adsorption was triggered by raising the pH to 11, pH at which CMC could be added. The pH was then lowered to 3. The process was repeated, and up to five polyelectrolyte layers were deposited on concentrated silica nanoparticles while inducing minimal aggregation.



Polyelectrolyte layers


Controlled assembly

Concentrated suspension




Krzysztof Kolman

Teknisk ytkemi

Nouryon Surface Chemistry AB

Giovanna Poggi

Universita degli Studi di Firenze

M. Baglioni

Universita degli Studi di Firenze

D. Chelazzi

Universita degli Studi di Firenze

P. Baglioni

Universita degli Studi di Firenze

Michael Persson

Chalmers, Kemi och kemiteknik, Energi och material

Nouryon Pulp and Performance Chemicals AB

Krister Holmberg

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Romain Bordes

Chalmers, Kemi och kemiteknik, Tillämpad kemi

Journal of Colloid and Interface Science

0021-9797 (ISSN) 1095-7103 (eISSN)

Vol. 615 265-272

NANOmaterials for the REStoration of works of ART (NANORESTART)

Europeiska kommissionen (EU) (EC/H2020/646063), 2015-06-01 -- 2018-12-31.


Fysikalisk kemi


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