Concentration dependent effects of urea binding to poly(N-isopropylacrylamide) brushes: a combined experimental and numerical study
dc.contributor.author | Micciulla, Samantha | |
dc.contributor.author | Michalowsky, Julian | |
dc.contributor.author | Schroer, Martin A. | |
dc.contributor.author | Holm, Christian | |
dc.contributor.author | Klitzing, Regine von | |
dc.contributor.author | Smiatek, Jens | |
dc.date.accessioned | 2017-10-24T06:17:20Z | |
dc.date.available | 2017-10-24T06:17:20Z | |
dc.date.issued | 2016 | |
dc.description.abstract | The binding effects of osmolytes on the conformational behavior of grafted polymers are studied in this work. In particular, we focus on the interactions between urea and poly(N-isopropylacrylamide) (PNIPAM) brushes by monitoring the ellipsometric brush thickness for varying urea concentrations over a broad temperature range. The interpretation of the obtained data is supported by atomistic molecular dynamics simulations, which provide detailed insights into the experimentally observed concentration-dependent effects on PNIPAM-urea interaction. In particular, in the low concentration regime (c(u) <= 0.5 mol L-1) a preferential exclusion of urea from PNIPAM chains is observed, while in the high concentration regime (2 <= c(u) <= 7 mol L-1) a preferential binding of the osmolyte to the polymer surface is found. In both regimes, the volume phase transition temperature (T-tr) decreases with increasing urea concentration. This phenomenon derives from two different effects depending on urea concentration: (i) for c(u) <= 0.5 mol L-1, the decrease of T-tr is explained by a decrease of the chemical potential of bulk water in the surrounding aqueous phase; (ii) for c(u) >= 2 mol L-1, the lower T-tr is explained by the favorable replacement of water molecules by urea, which can be regarded as a cross-linker between adjacent PNIPAM chains. Significant effects of the concentration-dependent urea binding on the brush conformation are noticed: at c(u) <= 0.5 mol L-1, although urea is loosely embedded between the hydrated polymer chains, it enhances the brush swelling by excluded volume effects. Beyond 0.5 mol L-1, the stronger interaction between PNIPAM and urea reduces the chain hydration, which in combination with cross-linking of monomer units induces the shrinkage of the polymer brush. | en |
dc.description.sponsorship | DFG, EXC 310, Simulationstechnik | en |
dc.description.sponsorship | DFG, SFB 716, Dynamische Simulation von Systemen mit großen Teilchenzahlen | en |
dc.description.sponsorship | DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interfaces | en |
dc.identifier.eissn | 1463-9084 | |
dc.identifier.issn | 1463-9076 | |
dc.identifier.pmid | 26817960 | |
dc.identifier.uri | https://depositonce.tu-berlin.de/handle/11303/6883 | |
dc.identifier.uri | http://dx.doi.org/10.14279/depositonce-6222 | |
dc.language.iso | en | |
dc.rights.uri | https://creativecommons.org/licenses/by-nc/3.0/ | |
dc.subject.ddc | 540 Chemie und zugeordnete Wissenschaften | de |
dc.title | Concentration dependent effects of urea binding to poly(N-isopropylacrylamide) brushes: a combined experimental and numerical study | en |
dc.type | Article | en |
dc.type.version | publishedVersion | en |
dcterms.bibliographicCitation.doi | 10.1039/c5cp07544k | |
dcterms.bibliographicCitation.issue | 7 | |
dcterms.bibliographicCitation.journaltitle | Physical chemistry, chemical physics | en |
dcterms.bibliographicCitation.originalpublishername | Royal Society of Chemistry | de |
dcterms.bibliographicCitation.originalpublisherplace | Cambridge | de |
dcterms.bibliographicCitation.pageend | 5335 | |
dcterms.bibliographicCitation.pagestart | 5324 | |
dcterms.bibliographicCitation.volume | 18 | |
tub.accessrights.dnb | free | |
tub.affiliation | Fak. 2 Mathematik und Naturwissenschaften::Inst. Chemie | de |
tub.affiliation.faculty | Fak. 2 Mathematik und Naturwissenschaften | de |
tub.affiliation.institute | Inst. Chemie | de |
tub.publisher.universityorinstitution | Technische Universität Berlin |
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