Effect of solvent on the free radical polymerization of N,N‐dimethylacrylamide

Abstract

The free radical photopolymerization of N,N-dimethylacrylamide was investigated at 25 • C and at low conversion in several solvents ranging from weak polar solvents to water. The polymerization is strongly accelerated in the aqueous medium, with the polymerization rate increasing one order of magnitude when the solvent is changed from an organic one to aqueous medium. These results were analysed in terms of macroradical conformation, effect of medium viscosity, aggregate formation, hydrogen bond formation and effect of temperature. The results suggest that the main factor that controls the polymerization rate is a kinetic effect due to the hydrogen bonding between the amide carbonyl group and water molecules. Also, we found that polymer properties, such as the thermodynamic quality of the solvent for the polymer backbone and molecular weight control using transfer agents, are influenced by the intermolecular hydrogen bonding.

Bioactive Peptide Brush Polymers via Photoinduced Reversible‐Deactivation Radical Polymerization

“…Table S3 in the Supporting Information summarizes the polymerization results for PepAm and DMA, indicating dramatically higher monomer conversions in water compared to those obtained by photo‐polymerizations in DMSO (Supporting Information, Table S1). We hypothesize that this is due to the hydrogen bonding between the amide carbonyl groups and water molecules, leading to enhanced solubility of PepAm in aqueous solution . Polymers (P10–P12) were analyzed by GPC and NMR spectroscopy (Supporting Information, Figures S22–S24) and showed molecular weights that were in good agreement with theoretical values, confirming that photo‐RDRP of PepAm was unaffected under aqueous conditions.…”

Cryopolymerization of N,N-dimethylacrylamide in moderately frozen formamide

“…However, it is not con ceivable that other factors are operative, for example, the formation of DMA-FA complexes that is due to hydrogen bonding. This phenomenon, in accordance with [25,26], may strongly affect the polymerization activity of unsaturated monomers and the molecular mass characteristics of the polymers; this effect is even stronger in the case of some protic solvents (water, alcohols), where a similar effect was observed for the polymerization of DMA in these solutions [27].…”

Rapid and quantitative one-pot synthesis of sequence-controlled polymers by radical polymerization

“…4) was employed (B95% of VA-044 is decomposed in 2 h, relatively similar to 81% of AIBN in 24 h). As the solvent choice may also significantly affect rate constants, we were interested in the use of water, which in addition to being environmental friendly and allowing the production of water-soluble macromolecules, is also known to increase k p of acrylamide monomers 14 . To further test the system, we focused on multiblock copolymers comprising a large number of very short blocks (average of three monomer units), as in all living radical polymerization (LRP) systems, targeting low degrees of polymerization leads to a greater number of chains and, therefore, a higher fraction of chains with an active chain end.…”