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Using jet mixing to prepare polyelectrolyte complexes: Complex properties and their interaction with silicon oxide surfaces
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.ORCID iD: 0000-0001-8622-0386
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
2010 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 351, no 1, 88-95 p.Article in journal (Refereed) Published
Abstract [en]

The influence of mixing procedure on the properties of polyelectrolyte complexes (PECs) was investigated using two complexation techniques, polyelectrolyte titration and jet mixing, the latter being a new method for PEC preparation. For the low-molecular-weight polyelectrolytes polyacrylic acid (PAA) and polyallyl amine hydrochloride (PAH), shorter mixing times produced smaller PECs, whereas for higher molecular weights of the same polyelectrolytes, PEC size first decreased with decreasing mixing time to a certain level, after which it started increasing again. This pattern was likely due to the diffusion-controlled formation of "pre-complexes", which, in the case of low-molecular-weight polymers, occurs sufficiently quickly to form stable complexes; when polyelectrolytes are larger, however, non-equilibrium pre-complexes, more prone to aggregation, are formed. Comparing the techniques revealed that jet mixing produced smaller complexes, allowing PEC size to be controlled by mixing time, which was not the case with polyelectrolyte titration. Higher polyelectrolyte concentration during jet mixing led to the formation of larger PECs. It was also demonstrated that PEC size could be changed after preparation: increasing the pH of the PEC dispersion led to an irreversible increase in PEC size, whereas lowering the pH did not influence PEC size. The adsorption behavior of PECs formed from weak polyelectrolytes on model substrates was studied using QCM-D, SPAR, and AFM imaging; the results indicated that increasing the pH increased the amount of PECs adsorbed to model surfaces. However, the amount of PECs adsorbed to the model surfaces was low compared with other systems in all studied cases.

Place, publisher, year, edition, pages
2010. Vol. 351, no 1, 88-95 p.
Keyword [en]
Adsorption, Jet mixing, Mixing time, Polyelectrolytes, Polyelectrolyte complex
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-26660DOI: 10.1016/j.jcis.2010.07.027ISI: 000282252700013ScopusID: 2-s2.0-77956228955OAI: diva2:373912
QC 20101202Available from: 2010-12-02 Created: 2010-11-26 Last updated: 2012-05-08Bibliographically approved
In thesis
1. Polyelectrolyte complexes: Preparation, characterization, and use for control of wet and dry adhesion between surfaces
Open this publication in new window or tab >>Polyelectrolyte complexes: Preparation, characterization, and use for control of wet and dry adhesion between surfaces
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis examines polyelectrolyte complex (PEC) preparation, adsorption behaviour, and potential use for control of wet and dry adhesion between surfaces.

PEC formation was studied using a jet-mixing method not previously used for mixing polyelectrolytes. The PECs were formed using various mixing times, and the results were compared with those for PECs formed using the conventional polyelectrolyte titration method. The results indicated that using the jet mixer allowed the size of the formed PECs to be controlled, which was not the case with the polyelectrolyte titration method, and a two-step mechanism for PEC formation was suggested.

Adsorption experiments comparing two types of PECs, both produced from PAA and PAH, but with different molecular weights, demonstrated that surface-induced aggregation occurred in the high-molecular-weight PECs, whereas the adsorption stopped at a low level in the low-molecular-weight PECs. It was suggested that the latter PECs consisted of two fractions of complexes and that the fraction with lower polymer density exerted a site-blocking effect, hindering further adsorption.

It was also demonstrated that particle-PECs (PPECs), in which one polyion was replaced with a silica nanoparticle, could be prepared. The purpose of preparing PPECs was to create a PEC structure that could create a joint with a special failure pattern referred to as disentanglement behaviour. Using the colloidal probe AFM technique, the expected disentanglement could be detected in PPECs, though the joint strength was low. Adhesion experiments demonstrated significantly higher pull-off values with polymer–polymer complexes than with PPECs. However, there was large spread in the data, possibly due to the surface inhomogeneity.

Experiments using low-molecular-weight PECs as a paper strength agent demonstrated that PECs can indeed increase paper strength. Comparing the PEC results with those for polyelectrolyte multilayers (PEMs) prepared from the same polyelectrolytes indicated that, since the PEM strategy enables higher adsorption levels than does the PEC strategy, greater absolute strength improvements could be achieved using PEMs. However, PEC treatment resulted in the greatest effect per adsorbed amount of polymer.

Abstract [sv]

Denna avhandling behandlar tillverkning av polyelektrolytkomplex (PEC), deras adsorption och potentiella användning för att öka adhesionen mellan ytor i vått och torrt.

PEC bildades med hjälp av jetmixningsmetoden, en metod som inte tidigare använts för PEC‑tillverkning. Resultaten av tillverkningen jämfördes med resultat för PEC bildade genom den tidigare ofta använda polyelektrolyt­titrerings­metoden. Jämförelsen visade att med jetmixningsmetoden kunde storleken på de bildade PECen styras med hjälp av blandningstiden, något som inte var möjligt med polyelektrolyttitreringsmetoden. Utifrån resultaten föreslås en två-stegsmekanism för PEC-bildandet.

Adsorptionsexperiment med två typer av PEC, båda tillverkade av PAA och PAH fast med olika molekylvikter, visade att för högmolekylära PEC skedde en ytinducerad aggregation, medan adsorptionen stannade på en låg nivå för de lågmolekylära PECen. De senare PECen antogs bestå av två olika fraktioner, av vilka en fraktion med lägre polymerdensitet föreslogs ha en ytblockerande effekt, och därigenom hindrades vidare adsorption.

Det visades också att partikel-PEC (PPEC), där ena polymerkomponenten bytts ut mot anjoniska nanopartiklar av kiseloxid, kunde tillverkas. Syftet var att skapa strukturer som kan åstadkomma ett brottmönster med uttrassling mellan ytor. Med hjälp av kolloidalprobs-AFM (atomkraftsmikroskopi) kunde det önskade uttrasslingsbeteendet påvisas, men fogstyrkan var låg. Adhesionsexperiment med polymer-polymer-PEC visade på högre styrkor än PPECen, men också stor spridning i data, troligen på grund av inhomogenitet i ytornas struktur.

Experiment där lågmolekylära PEC använts som styrkekemikalie för papper visade att tillsats av PEC kan öka pappersstyrkan. Jämförelse med resultat för poly­elektrolytmultilager (PEM) av samma komponenter visade att eftersom högre adsorptionsnivåer kan uppnås med PEM så kan större styrkeökningar erhållas med PEM. Däremot visades att den högsta styrkeökningen per adsorberad mängd polymer erhölls med PEC-behandlingen.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 50 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2012:12
National Category
Paper, Pulp and Fiber Technology
urn:nbn:se:kth:diva-94138 (URN)978-91-7501-333-6 (ISBN)
Public defence
2012-05-31, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
QC 20120508Available from: 2012-05-08 Created: 2012-05-08 Last updated: 2012-05-08Bibliographically approved

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