Bromoform‐Mediated Diblock Copolymerization of Acrylamide and N,N‐Dimethylacrylamide in Aqueous Solution

The diblock copolymerization of acrylamide (AM) and N,N ‐dimethylacrylamide (DMA) in aqueous solution has been studied. The synthesis methodology involved photoinitiation and the use of bromoform as a reversible chain transfer agent in a two‐step reversible deactivation radical polymerization (RDRP) type reaction. The main purpose of using bromoform was that it produced Br‐terminated chains of the first‐step polymer which, after photolysis of the terminal CBr bonds, could then act as macroinitiators in the polymerization of the second‐step monomer. The results showed that, although copolymerization occurred whether bromoform was used or not, adding bromoform increased the final copolymer molecular weight and, more importantly, exerted significantly more control over the composition of the final copolymer product. Although the AM and DMA monomers could be polymerized in either sequence, polymerizing the less reactive DMA first gave a more uniform final copolymer product in terms of its average composition and compositional distribution. This effect could also be related to the use of bromoform. Evidence in support of block copolymer formation was provided by a combination of analytical techniques: molecular weight characterization (viscometry, GPC), 1 H‐ and DOSY‐NMR and differential scanning calorimetry.