Diffusion of Sites versus Polymers in Polyelectrolyte Complexes and Multilayers.
It has long been assumed that the spontaneous formation of materials such as complexes and multilayers from charged polymers depends on (inter)diffusion of these polyelectrolytes. Here, we separately examine the mass transport of polymer molecules and extrinsic sites-charged polyelectrolyte repeat u...
| Publicado en: | Journal of the American Chemical Society Vol. 139; no. 41; pp. 14656 - 14668 |
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| Autores principales: | , |
| Formato: | Artículo |
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American Chemical Society
10/18/2017
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=125891793&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 125891793 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 10/18/2017 vid: 139 iid: 41 pid: 997 pub: American Chemical Society artinfo: ui: 125891793 10.1021/jacs.7b07905 ppf: 14656 ppct: 12 formats: tig: atl: Diffusion of Sites versus Polymers in Polyelectrolyte Complexes and Multilayers. aug: au: Fares, Hadi M. Schlenoff, Joseph B. affil: Department of Chemistry and Biochemistry, The Florida State University, Tallahassee, Florida 32306-4390, United States su: Polyelectrolytes Polymers Diffusion control Depolymerization Mass transfer Thin film crystallography Macromolecules sug: subj: Polyelectrolytes Polymers Diffusion control Depolymerization Mass transfer Thin film crystallography Macromolecules ab: It has long been assumed that the spontaneous formation of materials such as complexes and multilayers from charged polymers depends on (inter)diffusion of these polyelectrolytes. Here, we separately examine the mass transport of polymer molecules and extrinsic sites-charged polyelectrolyte repeat units balanced by counterions-within thin films of polyelectrolyte complex, PEC, using sensitive isotopic labeling techniques. The apparent diffusion coefficients of these sites within PEC films of poly(diallyldimethylammonium), PDADMA, and poly(styrenesulfonate), PSS, are at least 2 orders of magnitude faster than the diffusion of polyelectrolytes themselves. This is because site diffusion requires only local rearrangements of polyelectrolyte repeat units, placing far fewer kinetic limitations on the assembly of polyelectrolyte complexes in all of their forms. Site diffusion strongly depends on the salt concentration (ionic strength) of the environment, and diffusion of PDADMA sites is faster than that of PSS sites, accounting for the asymmetric nature of multilayer growth. Site diffusion is responsible for multilayer growth in the linear and into the exponential regimes, which explains how PDADMA can mysteriously "pass through" layers of PSS. Using quantitative relationships between site diffusion coefficient and salt concentration, conditions were identified that allowed the diffusion length to always exceed the film thickness, leading to full exponential growth over 3 orders of magnitude thickness. Both site and polymer diffusion were independent of molecular weight, suggesting that ion pairing density is a limiting factor. Polyelectrolyte complexes are examples of a broader class of dynamic bulk polymeric materials that (self-) assemble via the transport of cross-links or defects rather than actual molecules. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2017 holdings: @attributes: islocal: N |
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