Ca²⁺ and Cu²⁺ Induced Conformational Changes of Sodium Polymethacrylate in Dilute Aqueous Solution

Abstract

The coil contraction of sodium polymethacrylate in dilute aqueous sodium chloride solution (0.1 N, pH = 9) was monitored by static and dynamic light scattering when the Na+ ions were partly replaced by Ca2+ or Cu2+ ions. The effect was quantified as a function of polyion and bivalent metal ion concentration. The impact of Cu2+ ions on the chain conformation and the solubility of sodium polymethacrylate was observed to be larger than the corresponding effect of Ca2+ ions. This difference was ascribed to complexation of the carboxylate group with bivalent metal cations which is larger for the Cu2+ than for the Ca2+ ion. Even at the largest extent of contraction observed close to the precipitation threshold, the ratio of the radius of gyration and the hydrodynamic radius remained unchanged in contrast to the coil−globule transition observed for neutral polymer systems below the ϑ-temperature.

Experimental and theoretical study of dilute polyacrylamide solutions: effect of salt concentration

“…The viscosity of the system decreases. The higher the NaCl concentration is, the smaller the viscosity is [6,24,25]. As shown in Fig.…”

“…Previous researchers have reported reasonable results when they used less monomer for polymer simulation [22,23]. As reported the intrinsic viscosity greatly depended on the salt concentration [6,24]. When the HPAM is dissolved in deionized water, the HPAM macromolecule with the carboxylate groups (-COOˉ) can form an electrical double layer and thick hydration film, which can pack more H 2 O molecules.…”

Crystallization of Vaterite Nanowires by the Cooperative Interaction of Tailor-Made Nucleation Surfaces and Polyelectrolytes

“…From light-scattering experiments on poly(methacrylic acid), it is known that high concentrations of bivalent cations lead to an unfolding of the polymer chain, [20] which may be attributed to a complexation of the M 2+ cations and a concomitant loss of hydrogen bridges within the polymer. Similarly, polymer unfolding may be expected at basic pH values.…”

“…Thiols on gold-covered glass substrates are highly organized in two dimensions. [15,16,19] The advantage of this rather simple system is that the crystallization of calcium carbonate (or other inorganic compounds) on organic monolayers, [2,15,16] as well as the interaction of the polyelectrolyte with the bivalent cations, [20] can be easily monitored and is quite well understood. From in-situ neutron smallangle scattering studies of the crystallization of CaCO 3 on templated colloids in the presence of ovalbumin, it could be deduced that the mineral formation is a two-step process: in the first step CaCO 3 nanoparticles are formed which are transformed subsequently to CaCO 3 crystals.…”

Poly(sodium acrylate) hydrogels as potential pH-sensitive sorbents for the removal of model organic and inorganic pollutants from water

“…The combination of electrostatic attractions with hydrophobic interactions is usually the driving force in the case of cationic organic species, while polymer/metal ion coordination complexes are often formed when higher valency metal ions are involved. For (Francois et al, 1997;Gregor et al, 1955;Ikeda et al, 1998;Mun et al, 2003;Rivas et al, 2005;Yokoi et al, 1986). For simplicity reasons, the PANa-Cu 2+ complexation can be described by eq.…”