Organic acids as efficient catalysts for group transfer polymerization of N,N-disubstituted acrylamide with silyl ketene acetal: polymerization mechanism and synthesis of diblock copolymers

Abstract

ARTICLEThis journal is

Unprecedented Acid‐Promoted Polymerization and Gelation of Acrylamide: A Serendipitous Discovery

“…It is also used for wastewater treatment, oil recovery, papermaking, dermal fillers, personal care products and for various biomedical applications . Commercial high molecular weight polyacrylamide is obtained from conventional radical polymerization . It can be made in aqueous solution, in emulsions, in polar organic solvents or solvent‐free in bulk .…”

“…[18] Commercial high molecular weight polyacrylamide is obtained from conventionalr adical polymerization. [19,20] It can be made in aqueous solution, [21] in emulsions, [22] in polar organic solvents [19] or solvent-free in bulk. [23] Polymerization by redox-o rp hoto-initiators is generally preferred over the use of thermali nitiators because the reaction can be initiated at lower temperatures with better conversion.…”

Organocatalyzed Group Transfer Polymerization

“…Tris(pentafluorophenyl)borane (B(C 6 F 5 ) 3 ) was previously used as a cocatalyst component together with trialkylsilyl triflate for the GTPs of alkyl acrylates by Ute et al95 We believed that the high Lewis acidity of B(C 6 F 5 ) 3 itself was sufficient to catalyze the GTP of acrylic monomers. We therefore introduced the GTPs of N , N ‐disubstituted acrylamides (DAAs) using B(C 6 F 5 ) 3 96. The DAAs included N , N ‐dimethylacrylamide (DMAA), N , N ‐diethylacrylamide (DEAA), N , N ‐di‐ n ‐propylacrylamide (D n PAA), N ‐acryloylpiperidine (API), N ‐acryloylmorpholine (NAM), N ‐(2‐methoxyethyl)‐ N ‐methylacrylamide (MMEAA), N , N ‐bis(2‐methoxyethyl)acrylamide (BMEAA), N , N ‐diallylacrylamide (DAlAA), and N ‐methyl‐ N ‐propargylacrylamide (MPAA).…”

“…The solution to this issue is to find a dual‐role catalyst that is capable of simultaneously catalyzing a reaction to in situ produce an SKA and the GTP of the monomer in the same reaction system. We found that B(C 6 F 5 ) 3 is a good candidate for this purpose since (1) it effectively catalyzes the 1,4‐hydrosilation of an α,β‐unsaturated ketone with a hydrosilane to produce a silyl enolate99–103 and (2) the same catalyst promotes the GTPs of acrylic monomers 96. We have demonstrated a new GTP method using the B(C 6 F 5 ) 3 /HSiR 3 initiating system, as shown in Scheme .…”

“…In our group, the synthesis of well‐defined block copolymers has been readily achieved by the organocatalyzed GTP using the same types of monomers through the sequential addition approach, as shown in Scheme . The GTP using strong organic bases is only suitable for the synthesis of methacrylate block polymers, while the GTP using strong organic acids is more favorable for synthesizing acrylate and acrylamide block polymers 94,96. In contrast, the synthesis of well‐defined block polymers with different monomer type blocks has rarely been successful due to their very diverse monomer reactivity.…”