Journal Article

PreJuSER-55081

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Shrinking of anionic polyacrylate coils induced by Ca2+, Sr2+ and Ba2+: A combined light scattering and ASAXS study

Schweins, R. ; Goerigk, G.FZJ* ; Huber, K.

2006
Springer Berlin

This record in other databases:      

Please use a persistent id in citations: http://hdl.handle.net/2128/25331  doi:10.1140/epje/i2006-10047-7

Abstract: Anionic polyacrylate chains (NaPA) form precipitates if alkaline earth cations are added in stoichiometric amounts. Accordingly, precipitation thresholds were established for three different alkaline earth cations Ca(2+), Sr(2+) and Ba(2+). Close to the precipitation threshold, the NaPA chains significantly decrease in size. This shrinking process was followed by means of combined static and dynamic light scattering. Intermediates were generated by varying the ratio [MCl(2)]/[NaPA] with M denoting the respective alkaline earth cation. All experiments were performed at an inert salt level of 0.01M NaCl. Similar coil-to-sphere transitions could be observed with all three alkaline earth cations Ca(2+), Sr(2+) and Ba(2+). Based on these findings, supplementary conventional and anomalous small-angle X-ray scattering experiments using selected intermediates close to the precipitation threshold of SrPA were performed. The distribution of Sr counterions around the polyacrylate chains in aqueous solution provided the desired scattering contrast. Energy-dependent scattering experiments enabled successful separation of the pure-resonant terms, which solely stem from the counterions. The Sr(2+) scattering roughly reflects the monomer distribution of the polyacrylate chains. Different ratios of the concentrations of [ SrCl(2)]/[NaPA] revealed dramatic changes in the scattering curves. The scattering curve at the lowest ratio indicated an almost coil-like behaviour, while at the higher ratios the scattering curves supported the model of highly contracted polymer chains. Most of X-ray scattering experiments on intermediate states revealed compact structural elements which were significantly smaller than the respective overall size of the NaPA particles.

Keyword(s): Acrylic Resins: chemistry (MeSH) ; Anions (MeSH) ; Barium: chemistry (MeSH) ; Calcium: chemistry (MeSH) ; Cations, Divalent (MeSH) ; Chemical Precipitation (MeSH) ; Materials Testing (MeSH) ; Scattering, Small Angle (MeSH) ; Strontium: chemistry (MeSH) ; X-Ray Diffraction (MeSH) ; Acrylic Resins ; Anions ; Cations, Divalent ; Strontium ; Barium ; Calcium ; J

Note: Record converted from VDB: 12.11.2012

---

Contributing Institute(s):

1. Streumethoden (IFF-ISM)
2. JCNS (Jülich Centre for Neutron Science JCNS (JCNS) ; JCNS)
3. Neutronenstreuung (IFF-INS)

Research Program(s):

1. Kondensierte Materie (P54)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Appears in the scientific report 2006

---

Database coverage:

---