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  • PAA-PAMPS copolymers as an efficient tool to control CaCO3 scale formation.

PAA-PAMPS copolymers as an efficient tool to control CaCO3 scale formation.

Langmuir : the ACS journal of surfaces and colloids (2013-02-08)
Michael Dietzsch, Matthias Barz, Timo Schüler, Stefanie Klassen, Martin Schreiber, Moritz Susewind, Niklas Loges, Michael Lang, Nadja Hellmann, Monika Fritz, Karl Fischer, Patrick Theato, Angelika Kühnle, Manfred Schmidt, Rudolf Zentel, Wolfgang Tremel
ABSTRACT

Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4·2H2O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymerization. The derived copolymers had dispersities of 1.3 and below. The copolymers have then been investigated in detail regarding their impact on the different stages of the crystallization process of CaCO3. Ca(2+) complexation, the first step of a precipitation process, and polyelectrolyte stability in aqueous solution have been investigated by potentiometric measurements, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). A weak Ca(2+) induced copolymer aggregation without concomitant precipitation was observed. Nucleation, early particle growth, and colloidal stability have been monitored in situ with DLS. The copolymers retard or even completely suppress nucleation, most probably by complexation of solution aggregates. In addition, they stabilize existing CaCO3 particles in the nanometer regime. In situ AFM was used as a tool to verify the coordination of the copolymer to the calcite (104) crystal surface and to estimate its potential as a growth inhibitor in a supersaturated CaCO3 environment. All investigated copolymers instantly stopped further crystal growth. The carboxylate richest copolymer as the most promising antiscaling candidate proved its enormous potential in scale inhibition as well in an industrial-filming test (Fresenius standard method).

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Poly(acrylic acid, sodium salt) solution, average Mw ~8,000, 45 wt. % in H2O
Sigma-Aldrich
Poly(acrylic acid, sodium salt) solution, average Mw ~1,200, 45 wt. % in H2O
Sigma-Aldrich
Poly(acrylic acid) solution, average Mw ~250,000, 35 wt. % in H2O
Sigma-Aldrich
Poly(2-acrylamido-2-methyl-1-propanesulfonic acid) solution, average Mw 2,000,000, 15 wt. % in H2O
Sigma-Aldrich
Poly(acrylic acid) solution, average Mw ~100,000, 35 wt. % in H2O
Sigma-Aldrich
Poly(acrylic acid) solution, average Mw ~2,000, 50 wt. % in H2O, electronic grade
Sigma-Aldrich
Poly(acrylic acid)
Sigma-Aldrich
Poly(acrylic acid), average Mv ~4,000,000
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Poly(acrylic acid), average Mv ~3,000,000
Sigma-Aldrich
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Supelco
Poly(acrylic acid), analytical standard, average Mn 130,000 (Typical)
Sigma-Aldrich
Poly(acrylic acid), average Mv ~450,000
Sigma-Aldrich
Poly(acrylic acid), average Mv ~1,250,000
Sigma-Aldrich
Poly(acrylic acid sodium salt), average Mw ~5,100 by GPC, powder
Supelco
Poly(acrylic acid sodium salt), analytical standard, for GPC, 16,000