Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Surface Properties of Bottle-Brush Polyelectrolytes on Mica: Effects of Side Chain and Charge Densities
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
Department of Polymer Chemistry, Vilnius University.
Department of Polymer Chemistry, Vilnius University.
Show others and affiliations
2007 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 24, 12222-12232 p.Article in journal (Refereed) Published
Abstract [en]

Surface properties of a series of cationic bottle-brush polyelectrolytes with 45-unit-long poly(ethylene oxide) side chains were investigated by phase modulated ellipsometry and surface force measurements. The evaluation of the adsorbed mass of polymer on mica by means of ellipsometry is complex due to the transparency of mica and its birefringence and low dielectric constant. We therefore employed a new method to overcome these difficulties. The charge and the poly(ethylene oxide) side chain density of the bottle-brush polymers were varied from zero charge density and one side chain per segment to one charge per segment and no side chains, thus spanning the realm from a neutral bottle-brush polymer, via a partly charged brush polyelectrolyte, to a linear fully charged polyelectrolyte. The adsorption properties depend crucially on the polymer architecture. A minimum charge density of the polymer is required to facilitate adsorption to the oppositely charged surface. The maximum adsorbed amount and the maximum side chain density at the surface are obtained for the polymer with 50% charged segments and the remaining 50% of the segments carrying poly(ethylene oxide) side chains. It is found that brushlike layers are formed when 25-50% of the segments carry poly(ethylene oxide) side chains. In this paper, we argue that the repulsion between the side chains results in an adsorbed layer that is non-homogeneous on the molecular level. As a result, not all side chains will contribute equally to the steric repulsion but some will be stretched along the surface rather than perpendicular to it. By comparison with linear polyelectrolytes, it will be shown that the presence of the side chains counteracts adsorption. This is due to the entropic penalty of confining the side chains to the surface region.

Place, publisher, year, edition, pages
2007. Vol. 23, no 24, 12222-12232 p.
Keyword [en]
Birefringence; Charge density; Ellipsometry; Mica; Permittivity; Polyethylene oxides; Polymers; Bottle-brush polyelectrolytes; Linear polyelectrolytes; Steric repulsion
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-8142DOI: 10.1021/la701716tISI: 000250976700048Scopus ID: 2-s2.0-36649038755OAI: oai:DiVA.org:kth-8142DiVA: diva2:13387
Note
QC 20100813Available from: 2008-03-27 Created: 2008-03-27 Last updated: 2010-08-30Bibliographically approved
In thesis
1. Poly(Ethylene Oxide) Based Bottle-Brush Polymers and their Interaction with the Anionic Surfactant Sodium Dodecyl Sulphate: Solution and Interfacial Properties
Open this publication in new window or tab >>Poly(Ethylene Oxide) Based Bottle-Brush Polymers and their Interaction with the Anionic Surfactant Sodium Dodecyl Sulphate: Solution and Interfacial Properties
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The aim of this thesis work is to study the physico-chemical properties of poly(ethylene oxide), PEO, based brush polymers both in solution and at solid/aqueous interfaces. The importance of studying the surface properties of brush polymers can be related to a broad spectrum of interfacial-related applications such as colloidal stability, lubrication, detergency, protein repellency to name a few. In many applications it is desirable to form brush-like structures through simple physisorption. In this context the surface properties of PEO based brush polymers differing in molecular architecture were studied, using ellipsometry and surface force apparatus (SFA), to gain some understanding regarding the effect of molecular architecture on the formation of brush structures. The molecular architecture was varied by varying the charge/PEO ratio along the backbone. This study demonstrates that the formation of a brush structure at solid/aqueous interface is due to interplay between the attraction of the backbone to the surface and the repulsions between the PEO side chains. An optimal balance between the two antagonistic factors is required if one aims to build a well-defined brush structure at the interface. In this study the brush-like structures are formed when 25-50% of the backbone segments carry poly(ethylene oxide) side chains. Scattering techniques such as light and neutron reveal that these brush polymers are stiff-rods up to a charge to PEO ratio of 75:25. These stiff PEO brush polymer easily replace the more flexible linear PEO at the silica/water interface, the reason being that the entropy loss on adsorption is smaller for the brush polymer due to its stiff nature.  Polymer-surfactant systems play a ubiquitous role in many technical formulations. It is well known that linear PEO, which adopts random coil conformation in aqueous solution, interact strongly with the anionic surfactant, Sodium Dodecyl Sulphate (SDS). It is of interest to study the interaction between SDS and brush PEO owing to the fact that the PEO side chains have limited flexibility as compared to the linear PEO.  The interaction between brush PEO and the anionic surfactant SDS in solution are studied using different techniques such as NMR, tensiometry, SANS and light scattering. The main finding of this study is that the interaction is weaker compared to the linear PEO-SDS interactions which poses an interesting question regarding the role of chain flexibility in polymer-surfactant interactions.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. x, 68 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:17
Keyword
PEO brush polymers, brush polymers, PEO, poly(ethylene oxide), polymer-surfactant, sodium dodecyl sulphate (SDS), Ellipsomtery, PEO-SDS interactions
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-4680 (URN)978-91-7178-900-6 (ISBN)
Public defence
2008-04-11, E2, KTH, Lindstedtsvägen 26, Stockholm, 09:00
Opponent
Supervisors
Note
QC 20100813Available from: 2008-03-27 Created: 2008-03-27 Last updated: 2010-08-13Bibliographically approved
2. Polyelectrolytes: Bottle-Brush Architectures and Association with Surfactants
Open this publication in new window or tab >>Polyelectrolytes: Bottle-Brush Architectures and Association with Surfactants
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis has the dual purpose of raising awareness of the importance of the mixing protocol on the end products of polyelectrolyte-oppositely charged surfactant systems, and to contribute to a better understanding of the properties of bottle-brush polyelectrolytes when adsorbed onto interfaces.

In the first part of this thesis work, the effects of the mixing protocol and the mixing procedure on formed polyelectrolyte-oppositely charged surfactant aggregates were investigated. It was shown that the initial properties of the aggregates were highly dependent on the mixing parameters, and that the difference between the resulting aggregates persisted for long periods of time.

The second part of the studies was devoted to the surface properties of a series of bottle-brush polyelectrolytes made of charged segments and segments bearing poly(ethylene oxide) side chains; particular attention was paid to the effect of side chain to charge density ratio of the polyelectrolytes. It was shown that the adsorbed mass of the polyelectrolytes, and the corresponding number of poly(ethylene oxide) bearing segments at the interface, went through a maximum as the charge density of the polyelectrolyte was increased. Also, it was found that bottle-brush polyelectrolyte layers were desorbed quite easily when subjected to salt solutions. This observation was rationalized by the unfavourable excluded volume interactions between the side chains and the entropic penalty of confining them at an interface, which weaken the strength of the binding of the polyelectrolytes to the interface. However, it was shown that the same side chains effectively protect the adsorbed layer against desorption when the layer is exposed to solutions containing an oppositely charged surfactant. Investigation of the lubrication properties of the bottle-brush polyelectrolytes in an asymmetric (mica-silica) system also related the observed favourable frictional properties to the protective nature of the side chains. The decisive factor for achieving very low coefficients of friction was found to be the concentration of the side chains in the gap between the surfaces. Interestingly, it was shown that a brush-like conformation of the bottle-brush polyelectrolyte at the interface has little effect on achieving favourable lubrication properties. However, a brush-like conformation is vital for the resilience of the adsorbed layer against the competitive adsorption of species with a higher surface affinity.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 39 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:18
Keyword
Polyelectrolyte, Surfactant, Bottle-Brush Polyelectrolyte, Comb Polyelectrolyte, Non-Equilibrium State, Polymer Architecture, Adsorption, Desorption, Association, Excluded Volume, Light Scattering, SFA, AFM, QCM-D, Turbidimeter, Mica, Silica, Surface Forces
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-4683 (URN)978-91-7178-903-7 (ISBN)
Public defence
2008-04-18, F3, Lindstedsvägen 28 100 44, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100830Available from: 2008-03-27 Created: 2008-03-27 Last updated: 2012-01-20Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Naderi, AliIruthayaraj, JosephClaesson, Per M.
By organisation
Surface Chemistry
In the same journal
Langmuir
Physical Chemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 111 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf