Effect of counterions on comb-like polycarboxylate conformation in aqueous solutions |
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Authors: | Qian Zhang Hongxia Zhao Xin Shu Yong Yang |
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Institution: | 1. State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Research Institute of Building Science, Nanjing, Jiangsu, China;2. Jiangsu Sobute New Materials Co. Ltd., Nanjing, Jiangsu, China |
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Abstract: | Laser light scattering (LLS) and conductivity experiments were performed to investigate the effect of counterions on the conformation of polycarboxylate comb-like copolymers (PCEs) in aqueous solutions. The addition of monovalent ions (i.e., Na+ and K+) to dilute polycarboxylate comb-like copolymer solutions induced a slight shrinking of the molecular chains because of the screening of electrostatic intramolecular repulsion. Varying complexation phenomena, such as the formation of intramolecular complexation at certain Ca2+ concentrations and a transition between intermolecular and intramolecular complexations at different Ca2+ concentrations, were closely associated with Ca2+ concentration. Therefore, Ca2+ exerted a more complex influence on the conformation of PCEs with side chains containing polyethylene oxide (PEO) with different grafting densities. In addition, various combination types of Ca2+ with carboxylic groups were confirmed by theoretical simulation. |
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Keywords: | Comb-like copolymers conformation polycarboxylate counterions |
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