We investigate the self-organization of PSS in brushes and polyelectrolyte multilayers with X-ray, neutron and optical reflectivity. The electrostatic force dominates brush phases and adsorption behavior, additionally we find evidence of a strong hydrophobic force: (i) within amphiphilic diblock copolymer monolayers, a PSS monolayer adsorbs flatly to the hydrophobic block, (ii) on temperature increase (and with screened electrostatic forces), more PSS is adsorbed onto oppositely charged surfaces, and (iii) a polyelectrolyte multilayers shrinks when heated at 100% r.h. The latter two effects are consistent with the well-known increase of the hydrophobic force on heating: The increased PSS surface coverage can be attributed to deteriorating solvent conditions. Within a polyelectrolyte multilayer, an increase of the hydrophobic force maximizes the local contact of hydrophobic polymer segments, causing a reduction of swelling and an increased mass density.
Colloidal gold adsorbed onto positively charged substrates forms a two-dimensional layer with a maximum coverage of I colloid/1000 nm(2) as shown by optical absorption spectroscopy, small-angle X-ray scattering, and atomic force microscopy. Positively charged substrates are obtained by either chemisorption of end-group-functionalized silanes or by polycation adsorption. Bulk diffusion controls the gold adsorption; thus lower coverages can also be achieved. The optical spectra not only contain information on single colloids but also on their mutual interactions, as well as on the polymeric and solvent environments. Absorption spectra based on Mie and Maxwell-Garnett theory are calculated. The films remain stable on exchange of the external solvent. The local dielectric environment is shown to not only influence the position of the absorption band but also, more drastically, the intensity (by a factor of 2.5), in agreement with theoretical predictions (+/-15%). Particle aggregation induced by branched polycations causes an additional low-energy absorption peak.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEvidence against the putative E2C mechanism of olefin-forming eliminationDavid Eck and J. F. BunnettCite this: J. Am. Chem. Soc. 1969, 91, 11, 3099–3100Publication Date (Print):May 1, 1969Publication History Published online1 May 2002Published inissue 1 May 1969https://pubs.acs.org/doi/10.1021/ja01039a053https://doi.org/10.1021/ja01039a053research-articleACS PublicationsRequest reuse permissionsArticle Views37Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts