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Buildup of Polyelectrolyte Multilayers of Polyethyleneimine and Microfibrillated Cellulose Studied by in situ Dual Polarization Interferometry and Quartz Crystal Microbalance with Dissipation
KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.ORCID-id: 0000-0001-8622-0386
Visa övriga samt affilieringar
2008 (Engelska)Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, nr 6, s. 2509-2518Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Polyethyleneimine (PEI) and Microfibrillated cellulose (MFC) have been used to buildup polyelectrolyte multilayers (PEM) on silicone oxide and silicone oxynitride surfaces at different pH values and with different electrolyte and polyelectrolyte/colloid concns. of the components.  Consecutive adsorption on these surfaces was studied by in situ dual-polarization interferometry (DPI) and quartz crystal microbalance measurements.  The adsorption data obtained from both the techniques showed a steady buildup of multilayers.  High pH and electrolyte concn. of the PEI soln. was found to be beneficial for achieving a high adsorbed amt. of PEI, and hence of MFC, during the buildup of the multilayer.  On the other hand, an increase in the electrolyte concn. of the MFC dispersion was found to inhibit the adsorption of MFC onto PEI.  The adsorbed amt. of MFC was independent of the bulk MFC concn. in the investigated concn. range (15-250 mg/L).  At. force microscopy measurements were used to image a MFC-treated silicone oxynitride chip from DPI measurements.  The surface was found to be almost fully covered by randomly oriented microfibrils after the adsorption of only one bilayer of PEI/MFC.  The surface roughness expressed as the rms-roughness over 1 μm2 was calcd. to be 4.6 nm (1 bilayer).  The adsorbed amt. of PEI and MFC and the amt. of water entrapped by the individual layers in the multilayer structures were estd. by combining results from the two anal. techniques using the de Feijter formula.  These results indicate a total water content of ca. 41% in the PEM.

Ort, förlag, år, upplaga, sidor
American Chemical Society (ACS), 2008. Vol. 24, nr 6, s. 2509-2518
Nyckelord [en]
PAPER STRENGTH PROPERTIES; ADSORPTION PROPERTIES; SILICA SURFACES; WOOD FIBERS; THIN-FILMS; PROTEIN; ELLIPSOMETRY; KINETICS; GROWTH
Nationell ämneskategori
Polymerkemi
Identifikatorer
URN: urn:nbn:se:kth:diva-70183DOI: 10.1021/la7032884ISI: 000253941000036Scopus ID: 2-s2.0-42149121363OAI: oai:DiVA.org:kth-70183DiVA, id: diva2:486016
Anmärkning
QC 20120207Tillgänglig från: 2012-02-07 Skapad: 2012-01-30 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
Ingår i avhandling
1. Preparation, characterisation and wetting of fluorinated cellulose surfaces
Öppna denna publikation i ny flik eller fönster >>Preparation, characterisation and wetting of fluorinated cellulose surfaces
2007 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis deals with the wetting by oil mixtures of two different model cellulose surfaces. The surfaces studied were a regenerated cellulose (RG) surface prepared by spin-coating, and a film consisting of polyelectrolyte multilayers (PEM) of Poly(ethyleneimine) (PEI) and a carboxymethylated Microfibrillated Cellulose (MFC). After coating or covalently modifying the cellulose surfaces with various amounts of fluorosurfactants, the fluorinated cellulose films were used to follow the spreading mechanisms of the different oil mixtures. The viscosity and surface tension of the oil, as well as the dispersive surface energy of the cellulose surface, are essential parameters governing the spreading kinetics. X-ray Photoelectron Spectroscopy (XPS) and dispersive surface energy measurements were made on the cellulose films treated with fluorosurfactants. A strong correlation between the surface coverage of fluorine, the dispersive surface energy and the measured contact angle of the oil mixtures was found. For example, a dispersive surface energy less than 18 mN/m was required in order for the cellulose surface to be non-wetting (θe > 90º) by castor oil.

Significant parts of this work were devoted to the development of cellulose surfaces for the wetting studies. The formation of a PEM consisting of PEI and MFC was studied and the total layer thickness and adsorbed amount were optimized by combining Dual Polarization Interferometry (DPI) with a Quartz Crystal Microbalance with Dissipation (QCM-D). The adsorption behaviour as well as the influence of the charge density, pH and electrolyte concentration of PEI, and electrolyte concentration of the MFC dispersion on the adsorbed amount of MFC were investigated. Results indicate that a combination of a high pH, a fairly high electrolyte concentration for PEI solution together with low or zero electrolyte concentration for the MFC resulted in the largest possible adsorbed amounts of the individual PEI and MFC layers.

The structures of the two cellulose surfaces were characterised with atomic force microscopy measurements and a difference in terms of surface structure and roughness were observed. Both surfaces were however very smooth with calculated RMS roughness values in the range of a few nanometers.

The adsorption behaviour of water-dispersible fluorosurfactants physically adsorbed at various concentrations onto the two model cellulose surfaces was investigated using DPI. The aggregate structure of an anionic fluorosurfactant, perfluorooctadecanoic acid, dispersed in water was studied by Cryo Transmission Electron Microscopy (Cryo-TEM). The fluorosurfactants had an adsorption and desorption behaviour in water which was dependent on the fluorinated chain length and the aggregation form of the fluorosurfactant. Perfluorooctanoic acid and a commercial cationic fluorosurfactant with a formal composition of CF3 (CF2)nSO2NH(CH2)3-4N(CH3)3+I- was found to desorb from the MFC and RG surfaces upon rinsing with water, whereas perfluorooctadecanoic acid was strongly adsorbed to the surfaces. It is essential for a fluorosurfacatant to be strongly adsorbed to the cellulose surface even after rinsing to yield hydrophobic and lipophobic (oleophobic) properties with a large contact angle for oils and water.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2007. s. 27
Serie
Trita-CHE-Report, ISSN 1654-1081 ; 2007:71
Nationell ämneskategori
Pappers-, massa- och fiberteknik
Identifikatorer
urn:nbn:se:kth:diva-4587 (URN)
Presentation
2007-11-30, STFI-salen, STFI-Packforsk, KTH, Dorottning Kristinas väg 61, Stockholm, 10:00
Opponent
Handledare
Anmärkning
QC 20101103Tillgänglig från: 2007-12-18 Skapad: 2007-12-18 Senast uppdaterad: 2012-03-13Bibliografiskt granskad
2. Novel oil resistant cellulosic materials
Öppna denna publikation i ny flik eller fönster >>Novel oil resistant cellulosic materials
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The aim of this study has been to prepare and characterise oil resistant cellulosic materials, ranging from model surfaces to papers and aerogels. The cellulosic materials were made oil resistant by chemical and topographic modifications, based on surface energy, surface roughness and barrier approaches. Detailed wetting studies of the prepared cellulosic materials were made using contact angle measurements and standardised penetration tests with different alkanes and oil mixtures.

A significant part of the activities were devoted to the development of model cellulosic surfaces with different degrees of crystalline ordering for the wetting studies. Crystalline cellulose I, II and amorphous cellulose surfaces were prepared by spin-coating of cellulose nanocrystal or microfibrillated cellulose (MFC) dispersions, with Langmuir-Schaefer (LS) films or by a layer-by-layer (LbL) deposition technique. The formation of multilayers consisting of polyethyleneimine (PEI)/anionic MFC or cationic MFC/anionic MFC was further studied and optimized in terms of total layer thickness and adsorbed amount by combining Dual Polarization Interferometry (DPI) or Stagnation Point Adsorption Reflectrometry (SPAR) with a Quartz Crystal Microbalance with Dissipation (QCM-D).

The smooth cellulosic surfaces prepared had different molecular and mesostructure properties and different surface energies as shown by X-ray diffraction, Atomic Force Microscopy (AFM) imaging, ellipsometry measurements and contact angle measurements.

The cellulose model surfaces were found to be ideal for detailed wetting studies, and after the surface has been coated or covalently modified with various amounts of fluorosurfactants, the fluorinated cellulose films were used to follow the spreading mechanisms of different oil mixtures. The viscosity and surface tension of the oil mixtures, as well as the dispersive surface energy of the cellulose surfaces, were found to be essential parameters governing the spreading kinetics. A strong correlation was found between the surface concentration of fluorine, the dispersive surface energy and the measured contact angle of the oil mixtures.

Silicon surfaces possessing structural porous characteristics were fabricated by a plasma etching process. The structured silicon surfaces were coated with sulfate-stabilized cellulose I nanocrystals using the LbL technique. These artificial intrinsically oleophilic cellulose surfaces were made highly oleophobic when coated with a thin layer of fluorinated silanes. By comparison with flat cellulose surfaces, which are oleophilic, it is demonstrated that the surface energy and the surface texture are essential factors preventing oil from spreading on the surface and, thus, inducing the observed macroscopic oleophobic properties.

The use of the MFC for surface coating on base papers demonstrated very promising characteristics as packaging materials. Environmental-Scanning Electron Microscopy (E-SEM) micrographs indicated that the MFC layer reduced the sheet porosity, i.e. the dense structure formed by the nanofibers resulted in superior oil barrier properties. Attempts were made to link the procedure for preparation of the MFC dispersions to the resulting microstructure of the coatings, and film porosity and the film moisture content to the resulting permeability properties.

Finally, MFC aerogels were successfully prepared by freeze-drying. The surface texture of the porous aerogels was carefully controlled by adjusting the concentration of the MFC dispersion used for the freeze-drying. The different scales of roughness of the MFC aerogels were utilised, together with the very low surface energy created by fluorination of the aerogel, to induce highly oleophobic properties.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2009. s. ix, 55
Serie
Trita-CHE-Report, ISSN 1654-1081 ; 2009:57
Nyckelord
oleophobic, MFC, cellulose, oil resistant, contact angle, XPS, SEM
Nationell ämneskategori
Pappers-, massa- och fiberteknik
Identifikatorer
urn:nbn:se:kth:diva-11494 (URN)978-91-7415-476-4 (ISBN)
Disputation
2009-12-04, F3, Lindstedtvägen 26, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning
QC 20100623Tillgänglig från: 2009-11-17 Skapad: 2009-11-17 Senast uppdaterad: 2012-03-13Bibliografiskt granskad

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