Facile access to highly functionalized polyacrylamide with ultra-high molecular weight: Multicomponent initiators-based free radical polymerization

We report a novel multicomponent initiators-based copolymerization strategy for synthesizing of acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS) copolymers, denoted by P(AM-co-AMPS), with an ultra-high content of AMPS (≥50 mol%) and an ultra-high molecular weight (>107 g/mol), while achieving a high conversion rate of monomer (∼100.0 %). The multicomponent initiators contain a redox couple, an azo compound, and a catalyst. Our investigation into the mechanism suggested that the synergistic effect in different rate constant for initiator decomposition between redox and azo initiators was responsible for actualizing ultra-high molecular weight copolymers with high conversion rates of monomer. Moreover, copolymers with 75 mol% and 100 mol% of AMPS were synthesized to verify the advantage of the multicomponent initiators-based strategy, both of which exhibited ultra-high molecular weights and ultra-high monomer conversion rates. This study fills a long-standing gap in research on the polyacrylamide family by providing highly functionalized P(AM-co-AMPS) with an ultra-high molecular weight. Moreover, it reveals how multicomponent initiators reconcile the contradiction between the ultra-high molecular weight and the high conversion rate in copolymerization. A multicomponent initiators-based copolymerization strategy was proposed to successfully synthesize ultra-high molecular weight (>107 g/mol) acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS) copolymers, denoted by P(AM-co-AMPS), with an ultra-high content of AMPS (≥50 mol%) along with 100 % monomer conversion rate. The synergistic effect between redox initiator and azo initiator contributes to the high monomer conversion rate and ultra-high molecular weight. This work fills the long-standing shortage of ultra-high molecular weight and highly functionalized P(AM-co-AMPS) in polyacrylamide family. [Display omitted] •High molecular weight P(AM-co-AMPS) was synthesized using multicomponent initiators.•AMPS homopolymer with molecular weight approaching 107 g/mol was prepared.•Multicomponent initiators consist of redox couple, azo initiator, and catalyst.•Synergistic effect exists between redox couple and azo initiator.•Synergistic effect contributes to high molecular weight and high conversion rate.