Synthesis and Characterization of Poly(acrylic acid) Produced by RAFT Polymerization. Application as a Very Efficient Dispersant of CaCO₃, Kaolin, and TiO₂

Abstract

Poly(acrylic acid), PAA, was prepared by controlled radical polymerization with reversible addition-fragmentation chain transfer. Using trithiocarbonic acid dibenzyl ester, 1, and trithiocarbonic acid bis(1-phenylethyl) ester, 2, as chain transfer agents (CTA), the polymerization is controlled for low ratios [AA]:[CTA]. At higher ratios, the polymerization is plagued by transfer to solvent. Transfer to polymer is also detected at high conversion, as shown by the presence of branches in NMR spectroscopy. In its neutralized form, PAA chains are not all terminated by a thiol end group, as shown by elemental analysis, thiol titration, and MALDI TOF MS. Finally, dispersion of CaCO 3, kaolin, and TiO2 using these PAA reveals that the dispersion characteristics are significantly improved using low-polydispersity PAA.

Direct Synthesis of Controlled Poly(styrene‐co‐acrylic acid)s of Various Compositions by Nitroxide‐Mediated Random Copolymerization

“…This behavior was assigned to chain transfer to 1,4-dioxane, which creates new short chains, as was also found for SG1-mediated homopolymerization of acrylic acid, [36,37] as well as for the RAFT polymerizations performed in the same solvent. [23] This result shows that our system actually undergoes molar mass limitation at low initiator concentration, which is however less pronounced in copolymerization of A with styrene than in homopolymerization. [36,37] Additionally, it is likely that the chain transfer constant (and hence the impact of transfer on molar mass) depends on the comonomer composition.…”

“…Recently, the same group completed this work and showed, as an application, that low polydispersity poly(acrylic acid)s were very efficient dispersants of inorganic particles. [23] They also described the application of RAFT to the synthesis of controlled poly(butyl acrylate)-block-poly(acrylic acid) block copolymers, and their use as stabilizers in emulsion polymerization. [24] The controlled homopolymerization of acrylic acid was also performed at room temperature in the presence of dibenzyltrithiocarbonate, under 60 Co irradiation.…”

Experimental Requirements for an Efficient Control of Free‐Radical Polymerizations via the Reversible Addition‐Fragmentation Chain Transfer (RAFT) Process

“…MMA [117,361] BMA [342] Sty [9] [67,69,336,337,349,[361][362][363][364][365] AA [248,323,[366][367][368][369][370] 4VP [364] MA [336,337,[361][362][363] BA [323,362] …”

Synthesis of Symmetrical Triblock Copolymers of Styrene and N‐isopropylacrylamide Using Bifunctional Bis(trithiocarbonate)s as RAFT Agents

“…[64] Dibenzyltrithiocarbonate CTA7 served as reference, as it is an efficient bifunctional RAFT agent in the polymerization of St and acrylic monomers. [65][66][67] The bis(trithiocarbonate)s CTA1-CTA3 can be classified as type I bifunctional RAFT agents Z-C( --S) -S-R-S-C(--S) -Z, which lead to growing polymer chains that bear the active RAFT group at the outer ends of the polymer. In contrast, CTA4-CTA7 represent type II bifunctional RAFT agents R-S-C( --S) -Z-C(--S) -S-R, which provide polymers with the active RAFT groups in the center of the growing polymer chains (see Figure 1).…”