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Polyelectrolyte Multilayers from Cationic and Anionic Starch: Influence of Charge Density and Salt Concentration on the Properties of the Adsorbed Layers
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0001-8622-0386
2010 (English)In: Starke (Weinheim), ISSN 0038-9056, E-ISSN 1521-379X, Vol. 62, no 2, 102-114 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of the present work was for identify limits for the formation of stable polyelectrolyte multilayers (PEMs) from cationic and anionic starches (with degrees of substitution of 0.04-0.09) on SiO2 surfaces, taking account of the effect of the charge density of the starches and the salt concentration in the surrounding water phase. The experiments were performed at a pH of 6.3 using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). From these experiments it was concluded that it is possible to form PEMs by the adsorption of oppositely charged starches on SiO2 surfaces; it was also found that adsorption of the first layer is controlled both by electrostatic, non-ionic interactions and by pure steric restrictions, Le, geometrical restrictions, at the surface. The results also indicate that the charge density of the starch must exceed a certain value to allow multilayer formation and that this critical charge density increases with increasing salt concentration. The combination of charge densities of the cationic/anionic starches was also found to influence the adsorption behaviour, and the formed polyelectrolyte multilayers had a high water content of 69-92%.

Place, publisher, year, edition, pages
2010. Vol. 62, no 2, 102-114 p.
Keyword [en]
Model surfaces, Polyelectrolyte multilayer, Stagnation point adsorption, reflectometry, Starch, Quartz crystal microbalance, paper strength properties, wood fibers, adhesive properties, ionic-strength, adsorption, size, flow
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-19287DOI: 10.1002/star.200900176ISI: 000275242000005Scopus ID: 2-s2.0-77249173310OAI: oai:DiVA.org:kth-19287DiVA: diva2:337334
Note
QC 20100525, QC 20110930.Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Polyelectrolyte multilayers of cationic and anionic starch and their use for improving the strength of papers made from mechanical pulps
Open this publication in new window or tab >>Polyelectrolyte multilayers of cationic and anionic starch and their use for improving the strength of papers made from mechanical pulps
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Graphic paper is experiencing severe competition from other materials and, most of all, from other media. This means there is a great need to improve paper quality while reducing raw material and production costs. Polyelectrolyte multilayer (PEM) treatment (i.e., consecutively adding cationic and anionic polyelectrolytes to the charged surface of wood fibres and fines, to form layers of these polyelectrolytes on the fibres/fines) has in recent years been found to offer great potential both to introduce new properties and to improve the mechanical properties of papers made of the treated fibres.

The main objective of this thesis was to develop a strategy for the PEM treatment of cationic and anionic starch to improve the mechanical properties of paper made of thermomechanical pulp (TMP), since PEM treatment of fibres has displayed great potential to improve the mechanical properties of sheets made of chemical pulp. Mechanical pulp, however, has a large fine material content. Since the fine material is highly charged, polyelectrolyte consumption would be unacceptably high if the entire pulp were PEM treated, so we applied PEM treatment only to a fibre fraction of the pulps in most trials in the present work. The polyelectrolytes used for PEMs have so far mostly been well-defined, expensive ones unsuitable for use in standard paper grades; to develop a more economically realistic alternative, we used cationic and anionic starches.

PEM formation on SiO2 surfaces from three differently charged cationic and anionic starches was first evaluated at three different salt levels using quartz crystal microbalance with dissipation (QCM-D) and stagnation point adsorption reflectometry (SPAR). The starch combinations displaying the highest potential for stable PEM formation at higher salt concentrations were then evaluated on an entire TMP pulp, as well as on a fraction of the pulp to reduce the amount of starch needed for PEM formation.

The results indicate that it is possible to form PEMs from cationic and anionic starch on a SiO2 surface. The charge density, salt concentration, and combination of starches all influenced PEM formation. PEM formation on mechanical fibres produced large improvements in the mechanical properties of the sheets made of the treated fibres, and the tensile index, stretch-at-break, Z-strength, and Scott bond values all increased. Fractionating the pulp and PEM treating only a fraction of the pulp, the long fibre and middle fraction, produced large decreases in the amount of starch needed and large improvements in the mechanical properties of the sheets when no fine material was subsequently added. As untreated fine material was subsequently added, the improvement in mechanical properties decreased. PEM formation produced almost no reduction in formation and only a slight increase in sheet density.

Abstract [sv]

Grafiskt papper är under hård konkurrens från andra material och, framför allt, andra media.  På grund av detta finns det ett stort behov av att förbättra papperskvalitén samtidigt som råmaterial- och produktionskostnader sänks. Polyelektrolyt-multiskikt (multiskikt) på massa (dvs. växelvis adsorption av katjoniska och anjoniska polyelektrolyter till träfibrer och finmaterial) har på senare år visat sig ha bra potential både för att ge nya egenskaper och för att förbättra de mekaniska egenskaperna hos papper gjorda av behandlad fiber.

Huvudsyftet med denna avhandling var att utveckla en strategi för multiskiktsbehandling med katjonisk och anjonisk stärkelse för att förbättra de mekaniska egenskaperna hos papper gjort av behandlad termomekanisk massa (TMP). Multiskiktsbehandling av fiber har visat stor potential för att ge förbättrade mekaniska egenskaper till ark gjorda av behandlad kemisk massa. Mekanisk massa innehåller dock en stor andel högladdat finmaterial som kan öka mängden polyelektrolyt som krävs för multiskiktsbehandling, därför multiskiktsbehandlas bara en fraktion av massan i de flesta experiment i detta arbete. De polyelektrolyter som använts för multiskikt har hittills mest varit väldefinierade och dyra, och därmed opassande för användning i vanliga papperskvalitéer. För att utveckla ett mer realistiskt alternativ så användes katjonisk och anjonisk stärkelse i detta arbete.

Multiskiktsuppbyggnad på SiO2-ytor av tre katjoniska och tre anjoniska stärkelser med olika laddningsdensitet utvärderades först vid tre olika saltnivåer genom att använda kvartskristal‑mikrogravimetri (QCM-D) och reflektometri (SPAR). Stärkelsekombinationerna som uppvisade störst potential för en stabil multiskiktsuppbyggnad på högre saltkoncentrationer blev sedan utvärderade på en hel TMP-massa, men även på en fraktion av massan för att minska mängden stärkelse som krävdes för multiskiktsuppbyggnad.

Resultaten visar på att det är möjligt att bygga upp multiskikt av katjonisk och anjonisk stärkelse på en SiO2-yta. Laddningsdensiteten, saltkoncentrationen och kombinationen av stärkelser var faktorer som påverkade multiskiktsuppbyggnaden. Multiskiktsuppbyggnad på mekaniska fibrer gav stora förbättringar av de mekaniska egenskaperna hos ark gjorda av behandlad fiber, och dragindex, töjning, Z-styrka och Scott bond-värde ökade. Fraktionering av massan och multiskiktsbehandling av endast en del av massan, långfiber- och mellanfraktion, innebar att mycket mindre stärkelse behövdes och gav stora förbättringar av de mekaniska egenskaperna hos arken om inget obehandlat finmaterial tillsattes efteråt. Då obehandlat finmaterial tillsattes så blev förbättringarna hos de mekaniska egenskaperna mindre. Multiskitsuppbyggnad gav nästan ingen reduktion av formationen och endast en liten ökning i arkdensitet.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 57 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:16
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-10537 (URN)978-91-7415-294-4 (ISBN)
Presentation
2009-05-26, STFI-salen, STFI-Packforsk, KTH, Drottning Kristinas väg 61, Stockholm, 10:00 (Swedish)
Opponent
Supervisors
Available from: 2009-05-25 Created: 2009-05-25 Last updated: 2010-10-27Bibliographically approved
2. Molecular Interactions in Thin Films of Biopolymers, Colloids and Synthetic Polyelectrolytes
Open this publication in new window or tab >>Molecular Interactions in Thin Films of Biopolymers, Colloids and Synthetic Polyelectrolytes
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The development of the layer-by-layer (LbL) technique has turned out to be an efficient way to physically modify the surface properties of different materials, for example to improve the adhesive interactions between fibers in paper. The main objective of the work described in this thesis was to obtain fundamental data concerning the adhesive properties of wood biopolymers and LbL films, including the mechanical properties of the thin films, in order to shed light on the molecular mechanisms responsible for the adhesion between these materials.

LbLs constructed from poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA), starch containing LbL films, and LbL films containing nanofibrillated cellulose (NFC) were studied with respect to their adhesive and mechanical properties. The LbL formation was studied using a combination of stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D) and the adhesive properties of the different LbL films were studied in water using atomic force microscopy (AFM) colloidal probe measurements and under ambient conditions using the Johnson-Kendall-Roberts (JKR) approach. Finally the mechanical properties were investigated by mechanical buckling and the recently developed SIEBIMM technique (strain-induced elastic buckling instability for mechanical measurements).

From colloidal probe AFM measurements of the wet adhesive properties of surfaces treated with PAH/PAA it was concluded that the development of strong adhesive joints is very dependent on the mobility of the polyelectrolytes and interdiffusion across the interface between the LbL treated surfaces to allow for polymer entanglements.

Starch is a renewable, cost-efficient biopolymer that is already widely used in papermaking which makes it an interesting candidate for the formation of LbL films in practical systems. It was shown, using SPAR and QCM-D, that LbL films can be successfully constructed from cationic and anionic starches on silicon dioxide and on polydimethylsiloxane (PDMS) substrates. Colloidal probe AFM measurements showed that starch LbL treatment have potential for increasing the adhesive interaction between solid substrates to levels beyond those that can be reached by a single layer of cationic starch. Furthermore, it was shown by SIEBIMM measurements that the elastic properties of starch-containing LbL films can be tailored using different nanoparticles in combination with starch.

LbL films containing cellulose I nanofibrils were constructed using anionic NFC in combination with cationic NFC and poly(ethylene imine) (PEI) respectively. These NFC films were used as cellulose model surfaces and colloidal probe AFM was used to measure the adhesive interactions in water. Furthermore, PDMS caps were successfully coated by LbL films containing NFC which enabled the first known JKR adhesion measurements between cellulose/cellulose, cellulose/lignin and cellulose/glucomannan. The measured adhesion and adhesion hysteresis were similar for all three systems indicating that there are no profound differences in the interaction between different wood biopolymers. Finally, the elastic properties of PEI/NFC LbL films were investigated using SIEBIMM and it was shown that the stiffness of the films was highly dependent on the relative humidity.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. ix, 56 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2011:50
Keyword
Polyelectrolyte multilayers, Layer-by-Layer assembly, Adhesion, Adsorption, Young's modulus, Mechanical buckling, AFM, JKR, SPAR, QCM-D, SIEBIMM, PAH, PAA, Starch, NFC, Nanocellulose
National Category
Materials Chemistry Paper, Pulp and Fiber Technology Nano Technology
Identifiers
urn:nbn:se:kth:diva-41023 (URN)978-91-7501-098-4 (ISBN)
Public defence
2011-10-14, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20110923

Available from: 2011-09-23 Created: 2011-09-23 Last updated: 2014-10-03Bibliographically approved

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