By a News Reporter-Staff News Editor at Science Letter -- Researchers detail new data in Macromolecular Research. According to news originating from Urbana, Illinois, by NewsRx correspondents, research stated, "Microstructure of particles and polymers in concentrated polymer solutions are examined. Silica nanoparticles with diameters of 44 nm are suspended in concentrated poly(ethylene glycol) (PEG) solutions working with PEG molecular weights from 300 to 20 000."
Our news journalists obtained a quote from the research from the University of Illinois, "Using time-domain NMR, we explore the effects of PEG adsorption on the silica particles on the mobility of polymer segments. Our results reveal that polymer mobility varies from the particle surface to the bulk with different relaxation times; polymers are glassy near the particle surface and mobile in the bulk. While polymer segments adsorb to the particle surfaces to form a glassy layer in a molecular weight independent manner, the number of polymer segments with intermediate mobility between that of the glassy state and the bulk increases with molecular weight Systematic variations in the nanoparticle and polymer microstructure in concentrated polymer solutions are explored using contrast matching small angle neutron scattering techniques demonstrating that the thickness of adsorption layer of polymer segments increases with increasing PEG molecular weights supporting NMR observations. However, the particle microstructure evolves in a manner suggesting attractive interactions increase with molecular weight We compare experimental observations and predictions by the polymer reference interaction site model (PRISM) revealing the limits of the theory when applied to the silica concentrated PEG solution system.."
According to the news editors, the research concluded: "While PRISM predicts experimental observations in polymer and particle microstructure quantitatively at low molecular weight, it fails as molecular weight increases, suggesting that polymer configurations are not able to sample equilibrium configurations."
For more information on this research see: Molecular Weight Effects on Particle and Polymer Microstructure in Concentrated Polymer Solutions. Macromolecules, 2013;46(16):6634-6643. Macromolecules can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Macromolecules - www.pubs.acs.org/journal/mamobx)
The news correspondents report that additional information may be obtained from S.Y. Kim, University of Illinois, Dept. of Chem & Biomol Engn, Urbana, IL 61801, United States (see also Macromolecular Research).
Keywords for this news article include: Urbana, Illinois, United States, Macromolecular Research, North and Central America
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