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Dynamic and Equilibrium Properties of Adsorbed Polyelectrolyte Layers
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 66 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:25
Keyword [en]
adsorption; cellulose; conformation; flocculation; kinetics; model surfaces; polyelectrolytes; pulp fibres; Quartz Crystal Microbalance with Dissipation; silicon oxide; Stagnation Point Adsorption Reflectometry
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-4697ISBN: 978-91-7178-938-9 (print)OAI: oai:DiVA.org:kth-4697DiVA: diva2:13494
Public defence
2008-04-25, STFI-salen, STFI-Packforsk, Drottning Kristinas väg 61, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100720Available from: 2008-04-18 Created: 2008-04-18 Last updated: 2010-07-20Bibliographically approved
List of papers
1. Adsorption Kinetics of cationic Polyelectrolytes studied with Stagnation Point Adsorption Reflectometry and Quartz Crystal Microgravimetry
Open this publication in new window or tab >>Adsorption Kinetics of cationic Polyelectrolytes studied with Stagnation Point Adsorption Reflectometry and Quartz Crystal Microgravimetry
2008 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 14, 7329-7337 p.Article in journal (Refereed) Published
Abstract [en]

The effects of charge density, pH, and salt concentration on polyelectrolyte adsorption onto the oxidized surface of silicon wafers were studied using stagnation point adsorption reflectometry and quartz crystal microgravimetry. Five different polyelectrolytes-cationic polyacrylamides of four charge densities and one cationic dextran-were examined. The adsorption kinetics was characterized using each technique, and the adsorption kinetics observed was in line with the impinging jet theory and the theory for one-dimensional diffusion, respectively. The polyelectrolyte adsorption increased with pH as an effect of the increased silica surface charge. A maximum in the saturation adsorption for both types of polyelectrolytes was found at 10 mM NaCl concentration. A significant adsorption also occurred at I M NaCl, which indicated a significant nonionic contribution to the adsorption mechanism. The fraction of solvent in the adsorbed layer was determined to be 70-80% by combining the two analysis techniques. This indicated a loose structure of the adsorbed layer and an extended conformation at the surface, favoring loops and tails. However, considering the solution structure with a hydrodynamic diameter larger than 100 nm for the CPAM and a thickness of the adsorbed layer on the order of 10 nm, the results showed that the adsorption is accompanied by a drastic change in polymer conformation. Furthermore, this conformation change takes place on a time scale far shorter than seconds.

Keyword
Charge density; Concentration (process); Curve fitting; Electrolytes; Fluid dynamics; Fluid mechanics; Glucose; Nonmetals; Oxide minerals; pH effects; Polyelectrolytes; Polymers; Powders; Quartz; Reflection; Reflectometers; Silica; Silicate minerals; Silicon; Silicon compounds; Silicon wafers; Sodium alloys; Surface charge
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-6014 (URN)10.1021/la800198e (DOI)000257468300042 ()2-s2.0-47949120059 (Scopus ID)
Note
QC 20100719. Uppdaterad från manuskript till artikel (20100719).Available from: 2006-06-21 Created: 2006-06-21 Last updated: 2010-07-20Bibliographically approved
2. Conformation of preadsorbed Polyelectrolyte Layers on Silica studied by secondary Adsorption of Colloidal Silica
Open this publication in new window or tab >>Conformation of preadsorbed Polyelectrolyte Layers on Silica studied by secondary Adsorption of Colloidal Silica
2008 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 325, no 1, 84-92 p.Article in journal (Refereed) Published
Abstract [en]

The conformation of cationic polyelectrolytes preadsorbed on macroscopic silica surfaces was studied before and after addition of colloidal silica (CS) and compared to the fixation capacity of CS. The Study included two polyelectrolytes of equal charge density, cationic polyacrylamide and cationic dextran. Adsorbed amounts were determined with stagnation point adsorption reflectometry (SPAR) and quartz crystal microgravimetry (QCM). Unsaturated layers of polyelectrolyte were formed in SPAR by stopping the adsorption at a fractional coverage relative to saturation adsorption. These layers were probed by secondary saturation adsorption of colloidal silica (CS). At low salt concentrations a high fractional coverage of polyelectrolyte was required to attain adsorption of CS, while significant adsorption of CS was found also for low fractional coverages of polyelectrolyte at salt concentrations above 10 mM NaCl. Saturation adsorption of cationic polyacrylamide (CPAM) and cationic dextran (Cdextran) onto the silica surface was found to be similar, while the secondary adsorption of CS was significantly higher onto preadsorbed CPAM compared with Cdextran. The QCM and SPAR data together indicated that the adsorbed layer of Cdextran was thinner than CPAM, and that a loose, expanded layer was formed after adsorption of CS on CPAM but not on Cdextran.

Keyword
polyelectrolyte adsorption; conformation; cationic polyacrylamide; cationic dextran; colloidal silica; nanoparticles; reflectometry; quartz crystal microbalance
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-6015 (URN)10.1016/j.jcis.2008.05.023 (DOI)000258791800010 ()2-s2.0-47749100395 (Scopus ID)
Note
QC 20100720. Uppdaterad från manuskript till artikel (20100720).Available from: 2006-06-21 Created: 2006-06-21 Last updated: 2011-07-06Bibliographically approved
3. Polyelectrolyte Adsorption on Thin Cellulose Films Studied with Reflectometry and Quartz Crystal Microgravimetry with Dissipation
Open this publication in new window or tab >>Polyelectrolyte Adsorption on Thin Cellulose Films Studied with Reflectometry and Quartz Crystal Microgravimetry with Dissipation
2009 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 1, 134-141 p.Article in journal (Refereed) Published
Abstract [en]

Thin cellulose films were prepared by dissolving carboxymethylated cellulose fibers in N-methyl morpholine oxide and forming thin films on silicon wafers by spin-coating. The adsorption of cationic polyacrylamides and polydiallyldimethylammonium chloride onto these films was studied by stagnation point adsorption reflectometry (SPAR) and by quartz crystal microgravimetry with dissipation (QCM-D). The polyelectrolyte adsorption was studied by SPAR as a function of salt concentration, and it was found that the adsorption maximum was located at 1 mM NaCl for polyelectrolytes of low charge density and at 10 mM NaCl for polyelectrolytes of high charge density. Electrostatic screening led to complete elimination of the polyelectrolyte adsorption at salt concentrations of 300 mM NaCl. According to the QCM-D analysis, the cellulose films showed a pronounced swelling in water that took several hours to complete. Subsequent adsorption of polyelectrolytes onto the cellulose films led to a release of water from the cellulose, an effect that was substantial for polyelectrolytes of high charge density at low salt concentrations. The total mass change including water could therefore show either an increase or a decrease during adsorption onto the cellulose films, depending on the experimental conditions.

Keyword
Adsorption; Cellulose; Cellulose derivatives; Chlorine compounds; Dewatering; Dissolution; Electrolytes; Oxide films; Oxide minerals; Plastic films; Polyelectrolytes; Polymers; Quartz; Quartz crystal microbalances; Reflection; Reflectometers; Semiconducting silicon compounds; Silicon wafers; Sodium chloride; Spinning (fibers); Water analysis
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-14143 (URN)10.1021/bm8010193 (DOI)000262399600018 ()2-s2.0-58549093765 (Scopus ID)
Note
QC 20100720Available from: 2010-07-20 Created: 2010-07-20 Last updated: 2010-07-20Bibliographically approved
4. The adsorption of hyperbranched polymers on silicon oxide surfaces
Open this publication in new window or tab >>The adsorption of hyperbranched polymers on silicon oxide surfaces
2006 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 301, no 1, 32-39 p.Article in journal (Refereed) Published
Abstract [en]

The electrostatic interaction between quarternised hyperbranched polymers (polyesteramides) and a silicon oxide (SiO2) surface has been studied via adsorption studies with quartz crystal microbalance instrument with dissipation (QCM-D). Frequency shift (Delta f) results show that the increase in both pH and salt concentration positively affect the adsorbed amount of these polymers, calculated by Sauerbrey equation, on the QCM crystal. The adsorbed amount of HA1 (with lower molecular weight and higher charge density) was lower than that of HA2 (with higher molecular weight and lower charge density) in all experiments. It was also observed that there are no significant changes in the dissipation after adsorption of these polymers. This indicated that both hyperbranched polymers formed rigid adsorbed layers on the negative SiO2 surface. Additionally, the results were compared with adsorption of poly-DADMAC and the results showed that the hyperbranched polymers formed thicker and more rigid layers as compared with the poly-DADMAC.

Keyword
hyperbranched polymers, quartz crystal microbalance, adsorption, Sauerbrey equation, layer thickness, silicon oxide
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-14144 (URN)10.1016/j.jcis.2006.04.052 (DOI)000239538300004 ()2-s2.0-33746189858 (Scopus ID)
Note
QC 20100720Available from: 2010-07-20 Created: 2010-07-20 Last updated: 2010-07-20Bibliographically approved
5. Hyperbranched polymers as a fixing agent for dissolved and colloidal substances on fiber and SIO2 surfaces
Open this publication in new window or tab >>Hyperbranched polymers as a fixing agent for dissolved and colloidal substances on fiber and SIO2 surfaces
2007 (English)In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 46, no 7, 2212-2219 p.Article in journal (Refereed) Published
Abstract [en]

Hyperbranched polymers (polyesteramides) were used as a cationic fixing agent to remove dissolved and colloidal substances (DCS) from the water phase in a fiber suspension. The relative turbidity, electrophoretic mobility, and average diameter of the colloidal particles were determined as a function of polyelectrolyte concentration. The results indicated that maximum removal of DCS was achieved at about zero electrophoretic mobility of the suspension where the negative surface charges of particles were neutralized by the oppositely charged hyperbranched polymer. The amount of hyperbranched polymers needed to maximize DCS fixation on the fibers was higher than the amount of poly-DADMAC (diallyldimethylammonium chloride) needed to reach the same effect. This was found to be due to the lower molecular weight and lower charge density of hyperbranched polymers. The lower molecular mass allowed penetration of these polymers into pores of fibers that resulted in higher polymer consumption before removal of the dissolved and colloidal substances from the fiber suspensions. A lower charge density further resulted in a higher saturation adsorption of the hyperbranched polymer. Experiments with both DCS and model-latex particles showed that the initial increase in relative turbidity was due to the aggregation of particles before fixation to fibers. The results from quartz crystal microbalance with dissipation (QCM-D) experiments showed that the efficiency of hyperbranched polymer and poly-DADMAC was similar even if they had different structure. Therefore, this study highlights the importance of molecular mass and charge density of the polymers as well as the surface structure of polymer layers which in turn gives implications for development of new structures of fixing agents.

Keyword
Colloids; Dissolution; Electrophoretic mobility; Molecular weight; Suspensions (fluids); Turbidity; Cationic fixing agent; Hyperbranched polymers; Polyesteramides; Polymer consumption
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-14145 (URN)10.1021/ie061108b (DOI)000245041400043 ()2-s2.0-34247099335 (Scopus ID)
Note
QC 20100720Available from: 2010-07-20 Created: 2010-07-20 Last updated: 2010-07-20Bibliographically approved
6. Tailoring the chemistry of polyelectrolytes to control their adsorption on cellulosic surfaces
Open this publication in new window or tab >>Tailoring the chemistry of polyelectrolytes to control their adsorption on cellulosic surfaces
2009 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, Vol. 340, no 1-3, 135-142 p.Article in journal (Refereed) Published
Abstract [en]

The adsorption of two types of cationic polyacrylamides in the presence of a background electrolyte was studied on substrates including silicon oxide, kraft pulp fibres and thin films of regenerated cellulose. One of the polyelectrolytes was a conventional cationic polyacrylamide (MeCPAM) and the other was a benzyl-containing derivative of cationic polyacrylamide (BzCPAM). It was found that the aromatic substituents of BzCPAM strongly enhanced the adsorption on substrates of hydrophobically modified silicon oxide when a background electrolyte was present. A similar effect was also seen in the case of BzCPAM adsorption on unbleached pulp fibres, but in this case MeCPAM also exhibited a strong adsorption at high background electrolyte concentrations. On bleached pulp fibres, BzCPAM maintained a high adsorption up to a concentration of 100 mM NaCl whereas MeCPAM adsorption showed a significant decrease at this salt concentration. On model cellulose films, the adsorption of BzCPAM was similar to that of MeCPAM and the non-ionic interactions with cellulose appeared weak, since there was no adsorption of either polyelectrolyte in 300 mM NaCl.

Keyword
Cationic polyacrylamide, Hydrophobic modification, Polyelectrolyte adsorption, Non-ionic interactions, Silicon oxide, Pulp fibres, Model cellulose surface
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-14146 (URN)10.1016/j.colsurfa.2009.03.017 (DOI)000266227600019 ()2-s2.0-64849116930 (Scopus ID)
Note
QC 20100720Available from: 2010-07-20 Created: 2010-07-20 Last updated: 2010-07-20Bibliographically approved
7. Kinetics of sequential adsorption of polyelectrolyte multilayers on pulp fibres and their effect on paper strength
Open this publication in new window or tab >>Kinetics of sequential adsorption of polyelectrolyte multilayers on pulp fibres and their effect on paper strength
2007 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 22, no 2, 258-266 p.Article in journal (Refereed) Published
Abstract [en]

Conditions for sequential adsorption of polyelectrolyte multilayers (PEM) onto pulp fibres were investigated in terms of appropriate addition levels and adsorption times. The objective was a technical application for improved tensile strength of paper. Two common polyelectrolytes (PE) in papermaking, polyamideamine epichlorolrydrin (PAE) and carboxymethyl cellulose (CMC), were consecutively adsorbed onto long fibres from a bleached softwood kraft pulp, adding up to four PE layers on the fibre surfaces. Adsorption isotherms and adsorption kinetics were studied layer by layer, giving recommended addition levels and adsorption times for each layer. PAE adsorbed in larger amounts than CMC, 4 and 1 mg/g, respectively on fractionated pulp free of fines. For the kinetics, longer times were required to reach saturation adsorption for PAE compared to CMC, corresponding to three and two minutes, respectively. Tensile testing of handsheets based on both fractionated and beaten pulp showed that four PE layers increased the tensile index by about 50%, reaching levels of 34 (unbeaten) and 88 Nm/g (beaten), respectively. The effect of PEM on strain at break depended on the beating level as the fractionated pulp showed an improvement from 2.5 to 4.1% while beaten pulp showed a reduction from 6.1 to 4.5%.

Keyword
polyelectrolyte adsorption, adsorption kinetics, polyelectrolyte multilayers, adsorption isotherms, tensile strength, polyamide amine epichlorohydrine, carboxymethyl cellulose, bleached softwood kraft pulp
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-14147 (URN)10.3183/NPPRJ-2007-22-02-p258-266 (DOI)000248057800016 ()2-s2.0-34547335809 (Scopus ID)
Note
QC 20100720Available from: 2010-07-20 Created: 2010-07-20 Last updated: 2010-07-20Bibliographically approved

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