We have located links that may give you full text access.
Effect of Ca 2+ ion concentration on adsorption of poly(carboxylate ether)-based (PCE) superplasticizer on mica.
Journal of Colloid and Interface Science 2018 October 2
HYPOTHESIS: Poly(carboxylate ether)-based (PCE) superplasticizers consist of a carboxylic acid backbone and grafted poly(ethylene glycol) (PEG) side chains. Ca2+ ion bridging mechanism is commonly purported to control PCE's adsorption on negatively charged cement particle surfaces in cement suspension, thus PCE was expected to adsorb on negatively charged surfaces in synthetic pore solutions via Ca2+ /COO- interactions.
EXPERIMENTS: Adsorption behaviors of a commercial PCE on negatively charged mica were studied in aqueous electrolyte solutions by a surface forces apparatus.
FINDINGS: Direct force measurements indicated that the PCE adsorbed onto mica from 0.1 M K2 SO4 due to K+ ion chelation by the ether oxygen units CH2 CH2 O on the PEG chains, but surprisingly did not adsorb from either 0.1 M K2 SO4 with saturated Ca(OH)2 or 0.1 M Ca(NO3 )2 . The adsorption in K2 SO4 was weak, enabling the adsorbed PCE layers to be squeezed out under modest compression. Upon separating the surfaces, the PCE immediately achieved an identical re-adsorption. In high-calcium conditions, the PCE was highly positively charged due to Ca2+ ion chelation by PEG chains and backbone carboxylic groups COO- , and mica also underwent charge reversal due to electrostatic adsorption/binding of Ca2+ ions. Consequently, the interaction between mica and PCE was electrostatically repulsive and no PCE adsorption occurred. These findings can be explained by the complex interplay of ion chelation by PEG chains, electrostatic binding and screening interactions with charged surfaces in the presence of monovalent and divalent counterions, and ultimately charge reversal of both the charged surfaces and polyelectrolyte in high divalent ion conditions.
EXPERIMENTS: Adsorption behaviors of a commercial PCE on negatively charged mica were studied in aqueous electrolyte solutions by a surface forces apparatus.
FINDINGS: Direct force measurements indicated that the PCE adsorbed onto mica from 0.1 M K2 SO4 due to K+ ion chelation by the ether oxygen units CH2 CH2 O on the PEG chains, but surprisingly did not adsorb from either 0.1 M K2 SO4 with saturated Ca(OH)2 or 0.1 M Ca(NO3 )2 . The adsorption in K2 SO4 was weak, enabling the adsorbed PCE layers to be squeezed out under modest compression. Upon separating the surfaces, the PCE immediately achieved an identical re-adsorption. In high-calcium conditions, the PCE was highly positively charged due to Ca2+ ion chelation by PEG chains and backbone carboxylic groups COO- , and mica also underwent charge reversal due to electrostatic adsorption/binding of Ca2+ ions. Consequently, the interaction between mica and PCE was electrostatically repulsive and no PCE adsorption occurred. These findings can be explained by the complex interplay of ion chelation by PEG chains, electrostatic binding and screening interactions with charged surfaces in the presence of monovalent and divalent counterions, and ultimately charge reversal of both the charged surfaces and polyelectrolyte in high divalent ion conditions.
Full text links
Related Resources
Trending Papers
Challenges in Septic Shock: From New Hemodynamics to Blood Purification Therapies.Journal of Personalized Medicine 2024 Februrary 4
Molecular Targets of Novel Therapeutics for Diabetic Kidney Disease: A New Era of Nephroprotection.International Journal of Molecular Sciences 2024 April 4
The 'Ten Commandments' for the 2023 European Society of Cardiology guidelines for the management of endocarditis.European Heart Journal 2024 April 18
A Guide to the Use of Vasopressors and Inotropes for Patients in Shock.Journal of Intensive Care Medicine 2024 April 14
Diagnosis and Management of Cardiac Sarcoidosis: A Scientific Statement From the American Heart Association.Circulation 2024 April 19
Essential thrombocythaemia: A contemporary approach with new drugs on the horizon.British Journal of Haematology 2024 April 9
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app