Interactions of Anion-Exchange Resins with Polyacrylates in Atmosphere

Abstract

The interactions of polyacrylates (PAs with mean molecular weight of 4.5, 25, and 250 kDa; Na⁺,pa⁻) with anion exchange resins in the Br⁻ form (AXRs; -R⁺,Br⁻) were studied under practical conditions by reaction stoichiometry and spectroscopy. The stoichiometric or an excess amount of PA(4.5 kDa) completely replaced Br- in the AXRs of the cross-linking degree of 2 or 8%, respectively, to give (-R⁺,pa⁻), due to enhancement in selectivity of carboxylate group by multiple interactions. In contrast, PA(250 kDa) exchanged Br⁻ only on the surface of AXRs and did not penetrate into the resins; CO₂ was involved in the system to induce exchange with CO₃²⁻. Using the slightly acidic condition caused substantially no exchange by CO₃²⁻ but induced coextraction of PA with proton as free Hpa. PA(4.5 kDa) once penetrating into the resin phase as (-R⁺,pa⁻) or free Hpa was reversibly eluted under the appropriate conditions.