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Neutron Reflectometry Study of Swelling of Polyelectrolyte Multilayers in Water Vapors : Influence of Charge Density of the Polycation

Title data

Köhler, Ralf ; Dönch, Ingo ; Ott, Patrick ; Laschewsky, Andre ; Fery, Andreas ; Krastev, Rumen:
Neutron Reflectometry Study of Swelling of Polyelectrolyte Multilayers in Water Vapors : Influence of Charge Density of the Polycation.
In: Langmuir. Vol. 25 (2009) Issue 19 . - pp. 11576-11585.
ISSN 1520-5827
DOI: https://doi.org/10.1021/la901508w

Official URL: Volltext

Abstract in another language

We studied the swelling of polyelectrolyte (PE) multilayers (PEM) in water (H2O) vapors. The PEM were made from polyanion poly(styrene sulfonate) (PSS) and polycation poly(diallyldimethylammonium chloride)-N-methyl-N-vinylacetamide (pDADMAC-NMVA). While PSS is a fully charged polyanion, pDADMAC-NMVA is a random copolymer made of charged pDADMAC and uncharged NMVA monomer units. Variation of the relative amount of these two units allows for controlling the charge density of pDADMAC-NMVA. The degree of swelling was studied as it function of the relative humidity in the experimental chamber (respectively water concentration in the gas phase) for PEM prepared from PSS and pDADMAC-NMVA with their different charge densities - 100, 89 and 75. The films were prepared by means of spraying technique and consisted of six PE couples-PSS/pDADMAC-NMVA. Neutron reflectometry was applied as main tool to observe the swelling process. The technique allows to obtain in a single experiment information about film thickness and amount of water in the film. The experiments were complemented with AFM measurements to obtain the thickness of the films. It was found that the Film thickness increases when the charge density of the polycation decreases. The swelling of the PEM increases with the relative humidity and it depends on the charge density of pDADMAC-NMVA. The swelling behavior is 2-fold, splitting up in a charge dependent mode with relatively little volume increase, and a second mode With high volume expansion, which is independent from charge density of PEM. The "swelling transition" occurs for all samples at a relative humidity about 60 and a volume increase of ca. 20. The results were interpreted according to the Flory-Huggins theory which assumes a phase separation in PEM network at higher water contents.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors > Chair Physical Chemistry II - Univ.-Prof. Dr. Andreas Fery
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Physical Chemistry II
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 500 Natural sciences
500 Science > 530 Physics
500 Science > 540 Chemistry
Date Deposited: 08 Dec 2014 09:58
Last Modified: 18 Feb 2015 14:09
URI: https://eref.uni-bayreuth.de/id/eprint/4004