Modification of surfaces with adsorption of amphiphilic polymers

Katri Kontturi

Modification of surfaces with adsorption of amphiphilic polymers

Julkaisun otsikon käännös: Pintaominaisuuksien muokkaaminen amfifiilisten polymeerien adsorptiolla

Katri Kontturi

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Tässä työssä tutkittiin amfifiilisten polymeerien adsorptiota ja hyödyntämistä tasomaisten pintojen muokkauksessa. Aihetta lähestyttiin tarkastelemalla systemaattisesti monien erityyppisten polymeerien adsorptiota ja adsorption vaikutuksia erilaisten tarkoin tunnettujen mallipintojen ominaisuuksiin. Tutkitut polymeerit olivat kationisen tärkkelyksen johdannaisia sekä erilaisia liukoisuudeltaan vaihtelevia varattuja ja neutraaleja synteettisiä lohkorakenteisia amfifiilisiä polymeerejä. Käsiteltävistä pinnoista keskeisessä roolissa olivat selluloosapohjaiset ohutkalvot, ja tutkimusta täydennettiin muilla tunnetuilla hydrofiilisilla ja hydrofobisilla mallipinnoilla. Riippumatta amfifiilisen polyelektrolyytin molekyylirakenteesta, molekyylin korkea hydrofobointiaste ja tai riittävä elektrostaattisen repulsion varjostaminen lisäämällä polymeeriliuokseen yksinkertaista elektrolyyttiä kasvattivat merkittävästi anionisille pinnoille adsorboituvan polymeerikerroksen paksuutta. Hydrofobiset pinnat pyrkivät minimoimaan rajapintansa veden kanssa, mistä johtuen erilaiset polymeerit adsorboituivat vesiliuoksesta hydrofobisille pinnoille riippumatta siitä, oliko polymeerin ja pinnan välillä affiniteettia. Vaikka amfifiilisten polyelektrolyyttien hydrofobointiaste vaikutti adsorboituvan polymeerikerroksen peittävyyteen, ei täysin peittävää kerrosta hydrofobiselle pinnalle yleensä muodostunut. Selluloosan amfifiilinen luonne tuli esiin systeemeissä, joissa adsorptio ei ollut voimakkaiden elektrostaattisten vuorovaikutusten ajamaa. Hydrofobisesti päätemodifioitu polyeteeniglykoli pystyi kiinnittymään amfifiiliseen selluloosapintaan vähemmän rajoitetussa konformaatiossa kuin puhtaasti hydrofiiliseen tai hydrofobiseen pintaan, minkä vuoksi verkkomaisen kerrosrakenteen muodostuminen selluloosapinnalle oli mahdollista. Elektrostaattisten voimien vallitessa selluloosa erottui muista käytetyistä anionisista mallipinnoista (piidioksidi ja kiille) varaustiheytensä ja huokoisuutensa vuoksi. Regeneroidun selluloosan matalan varauksen vuoksi korkeasti varatut polymeerit eivät voineet adsorboitua pinnalle ojentuneeseen konformaatioon. Toisaalta adsorboituvat molekyylit tunkeutuivat huokoisten selluloosafilmien sisään. Kationisten (amfifiilisten) molekyylien adsorptio vaikutti voimakkaasti selluloosapohjaisten materiaalien pinnan kastuvuuteen ja turpoamiseen. Voimakkaasti hydrofobisten veteen liukenemattomien misellien muodostama paksu ja karhea kerros vähensi pinnan hydrofiilisyytta tehokkaimmin. Misellien hydrofobointiteho kasvoi voimakkaasti, kun adsorboitunutta kerrosta hehkutettiin misellin ytimen lasiutumislämpötilan yläpuolella.

Julkaisun otsikon käännös	Pintaominaisuuksien muokkaaminen amfifiilisten polymeerien adsorptiolla
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Laine, Janne, Vastuuprofessori Laine, Janne, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-5442-1
Sähköinen ISBN	978-952-60-5443-8
Tila	Julkaistu - 2013
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

polymeeriadsorptio
amfifiiliset polymeerit
polyelektrolyytit
pinnan muokkaaminen
mallipinnat
selluloosa

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-5443-8

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@phdthesis{125476003cbd49969b84fc0dcfd3c65c,

title = "Modification of surfaces with adsorption of amphiphilic polymers",

abstract = "In this work the adsorption of amphiphilic polymers and their utilization in the modification of planar surfaces were examined. The approach was to systematically explore adsorption of very different types of polymers, including derivatives of cationic starch (CS), both charged and neutral synthetic block-structured polymers with amphiphilic character and different levels of solubility, on different well-defined model surfaces and the consequential changes in the properties of the surfaces. Cellulosic substrates were in the main role, complemented with other surfaces of hydrophilic or hydrophobic nature. Independent of the molecular architecture of an amphiphilic polyelectrolyte, a high degree of hydrophobic modification and/or sufficient screening of repulsive charges by added simple electrolyte significantly increased the thickness of the layer adsorbed on anionic surfaces. When it came to hydrophobic surfaces, the adsorption of different polymers from aqueous solution was favored regardless of the actual affinity, due to the tendency of the system to minimize the contact between the hydrophobic substrate and water. Although the degree of hydrophobic modification of amphiphilic polyelectrolytes correlated with the resulting surface coverage, formation of a uniform polymer layer was rarely obtained. The intrinsic amphiphilic nature of cellulose became efficient in a system where adsorption was not ruled by strong electrostatic forces. Due to its amphiphilicity, cellulose allowed hydrophobically end-modified poly(ethylene glycol) to attach onto the surface in a less strict conformation than on merely hydrophilic or hydrophobic surfaces, enabling formation of a network-structured layer. As a substrate for electrostatically driven adsorption, the cellulose substrate diverges from other studied hydrophilic substrates (silica and mica) due to its low charge density and porosity. Low charge of regenerated cellulose hinders highly charged molecules from adapting flat conformations on the surface. On the other hand, the porous structure allows penetration of the molecules into cellulosic films. The wettability and swelling properties of cellulosic materials were strongly affected by adsorption of cationic (amphiphilic) substances. A thick and rough layer of highly hydrophobic, kinetically trapped micelles decreased the hydrophilicity of the surface most efficiently. The hydrophobizing potential of the micelles was strongly strengthened by annealing above the glass transition temperature of the micellar core.",

keywords = "polymer adsorption, amphiphilic polymers, polyelectrolytes, surface modification, model surfaces, cellulose, polymeeriadsorptio, amfifiiliset polymeerit, polyelektrolyytit, pinnan muokkaaminen, mallipinnat, selluloosa, polymer adsorption, amphiphilic polymers, polyelectrolytes, surface modification, model surfaces, cellulose",

author = "Katri Kontturi",

year = "2013",

language = "English",

isbn = "978-952-60-5442-1",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "189",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Modification of surfaces with adsorption of amphiphilic polymers

AU - Kontturi, Katri

PY - 2013

Y1 - 2013

N2 - In this work the adsorption of amphiphilic polymers and their utilization in the modification of planar surfaces were examined. The approach was to systematically explore adsorption of very different types of polymers, including derivatives of cationic starch (CS), both charged and neutral synthetic block-structured polymers with amphiphilic character and different levels of solubility, on different well-defined model surfaces and the consequential changes in the properties of the surfaces. Cellulosic substrates were in the main role, complemented with other surfaces of hydrophilic or hydrophobic nature. Independent of the molecular architecture of an amphiphilic polyelectrolyte, a high degree of hydrophobic modification and/or sufficient screening of repulsive charges by added simple electrolyte significantly increased the thickness of the layer adsorbed on anionic surfaces. When it came to hydrophobic surfaces, the adsorption of different polymers from aqueous solution was favored regardless of the actual affinity, due to the tendency of the system to minimize the contact between the hydrophobic substrate and water. Although the degree of hydrophobic modification of amphiphilic polyelectrolytes correlated with the resulting surface coverage, formation of a uniform polymer layer was rarely obtained. The intrinsic amphiphilic nature of cellulose became efficient in a system where adsorption was not ruled by strong electrostatic forces. Due to its amphiphilicity, cellulose allowed hydrophobically end-modified poly(ethylene glycol) to attach onto the surface in a less strict conformation than on merely hydrophilic or hydrophobic surfaces, enabling formation of a network-structured layer. As a substrate for electrostatically driven adsorption, the cellulose substrate diverges from other studied hydrophilic substrates (silica and mica) due to its low charge density and porosity. Low charge of regenerated cellulose hinders highly charged molecules from adapting flat conformations on the surface. On the other hand, the porous structure allows penetration of the molecules into cellulosic films. The wettability and swelling properties of cellulosic materials were strongly affected by adsorption of cationic (amphiphilic) substances. A thick and rough layer of highly hydrophobic, kinetically trapped micelles decreased the hydrophilicity of the surface most efficiently. The hydrophobizing potential of the micelles was strongly strengthened by annealing above the glass transition temperature of the micellar core.

AB - In this work the adsorption of amphiphilic polymers and their utilization in the modification of planar surfaces were examined. The approach was to systematically explore adsorption of very different types of polymers, including derivatives of cationic starch (CS), both charged and neutral synthetic block-structured polymers with amphiphilic character and different levels of solubility, on different well-defined model surfaces and the consequential changes in the properties of the surfaces. Cellulosic substrates were in the main role, complemented with other surfaces of hydrophilic or hydrophobic nature. Independent of the molecular architecture of an amphiphilic polyelectrolyte, a high degree of hydrophobic modification and/or sufficient screening of repulsive charges by added simple electrolyte significantly increased the thickness of the layer adsorbed on anionic surfaces. When it came to hydrophobic surfaces, the adsorption of different polymers from aqueous solution was favored regardless of the actual affinity, due to the tendency of the system to minimize the contact between the hydrophobic substrate and water. Although the degree of hydrophobic modification of amphiphilic polyelectrolytes correlated with the resulting surface coverage, formation of a uniform polymer layer was rarely obtained. The intrinsic amphiphilic nature of cellulose became efficient in a system where adsorption was not ruled by strong electrostatic forces. Due to its amphiphilicity, cellulose allowed hydrophobically end-modified poly(ethylene glycol) to attach onto the surface in a less strict conformation than on merely hydrophilic or hydrophobic surfaces, enabling formation of a network-structured layer. As a substrate for electrostatically driven adsorption, the cellulose substrate diverges from other studied hydrophilic substrates (silica and mica) due to its low charge density and porosity. Low charge of regenerated cellulose hinders highly charged molecules from adapting flat conformations on the surface. On the other hand, the porous structure allows penetration of the molecules into cellulosic films. The wettability and swelling properties of cellulosic materials were strongly affected by adsorption of cationic (amphiphilic) substances. A thick and rough layer of highly hydrophobic, kinetically trapped micelles decreased the hydrophilicity of the surface most efficiently. The hydrophobizing potential of the micelles was strongly strengthened by annealing above the glass transition temperature of the micellar core.

KW - polymer adsorption

KW - amphiphilic polymers

KW - polyelectrolytes

KW - surface modification

KW - model surfaces

KW - cellulose

KW - polymeeriadsorptio

KW - amfifiiliset polymeerit

KW - polyelektrolyytit

KW - pinnan muokkaaminen

KW - mallipinnat

KW - selluloosa

KW - polymer adsorption

KW - amphiphilic polymers

KW - polyelectrolytes

KW - surface modification

KW - model surfaces

KW - cellulose

M3 - Doctoral Thesis

SN - 978-952-60-5442-1

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Modification of surfaces with adsorption of amphiphilic polymers

Abstrakti

Tutkimusalat

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