RAFT Polymerization of N,N-Dimethylacrylamide in Water

Abstract

Introduction. Controlled radical polymerization 1 (CRP) has been the focus of intense research in recent years. Atom transfer radical polymerization (ATRP), 2 nitroxide-mediated polymerization (NMP), 3 and more recently, reversible addition-fragmentation chain transfer polymerization (RAFT) 4 have allowed for the synthesis of (co)polymers with designated molecular weights and narrow molecular weight distributions.Considering the advantages of precisely controlled structures and the need for environmentally viable technologies, we have recently centered our efforts on conducting CRP in aqueous media. We first reported the synthesis, via RAFT, of homopolymers and block copolymers based on the water-soluble styrenic monomers, sodium 4-styrenesulfonate, sodium 4-styrenecarboxylate, N,N-dimethylvinylbenzylamine, and (ar-vinylbenzyl)trimethylammonium chloride. 5 Subsequently, we reported the first example of CRP of anionic acrylamido monomers in aqueous media. 6 As well as ionic monomers, we are interested in polymerizing nonionic hydrophilic/water-soluble species, such as N,N-dimethylacrylamide (DMA) via RAFT. Herein, we report the CRP of DMA, in aqueous media, utilizing two RAFT CTAs, Table 1. As far as we are aware, this constitutes the first report outlining the CRP of this monomer via RAFT in water.The CRP of DMA, and acrylamido monomers in general, has proven to be challenging using techniques such as ATRP and NMP. Li and Brittain reported the polymerization of DMA by NMP using TEMPO, but the process was shown to be uncontrolled. 7 However, with the development of more universal nitroxides, Benoit et al. demonstrated the ability to (co)polymerize DMA via NMP. 8 Teodorescu and Matyjaszewski reported the ATRP of several (meth)acrylamides. 9 However, the authors concluded that these systems were not "living". This was subsequently confirmed by Rademacher et al. 10 Senoo et al. reported the ATRP synthesis of PDMA, employing the RuCl 2 (PPh 3 ) 3 -based initiating system, although resulting polydispersities were typically >1.60. 11 With the discovery of RAFT, a wider range of monomers are now amenable to CRP. Significantly, the CRP of DMA 12 and N-isopropylacrylamide, 13 via RAFT, in organic media have already been demonstrated.In the work reported here, DMA homopolymers were synthesized in water via RAFT. Both sodium 4-cyanopentanoic acid dithiobenzoate (CTPNa) and N,N-dimethyl-s-thiobenzoylthiopropionamide (TBP) were employed as the RAFT chain transfer agents (CTAs). CTPNa was chosen due to its inherent water-solubility

Stabilization of volume gratings recorded in polyvinyl alcohol-acrylamide photopolymers with diffraction efficiencies higher than 90%

“…This finding was to be expected if we consider the studies in which attempts were made to polymerize AA and BMAA by heating [19], when it is reported that 300 min are necessary to achieve maximum polymerization. For this reason, we used a plate of similar characteristics and heated it to 80 C for 200 min.…”

“…Moreover, if this volume grating is exposed to white light, all the parameters (thickness, absorption constant and refraction index modulation) remain constant. The methods used to eliminate the residual monomer and residual dye consist in placing the photopolymer under green light (514 nm), under white light (luminance of 1200 lux) and a heating process, since the acrylamide and bisacrylamide polymerize when the temperature is sufficiently high [19]. Finally, we analyse the conservation of gratings recorded under extreme conditions of temperature and humidity.…”

Chain-End Functionalized Nanopatterned Polymer Brushes Grown via in Situ Nitroxide Free Radical Exchange

“…These include NMP, [27][28][29][30] atom transfer radical polymerization (ATRP), [31][32][33][34] and reversible additionϪfragmentation chain transfer (RAFT). 35,36 Initial experiments to test the nitroxide exchange principle were performed from flat polymer films. Accordingly, the inimer containing methacrylate-based photopolymer was applied to a silicon wafer surface by spin-coating and cured under UV light (365 nm).…”

"Smart" Multifunctional Polymers for Enhanced Oil Recovery

“…Major advances toward this goal have been realized in RAFT polymerization yielding water-soluble polymers with well-controlled structures. For example homopolymers and block copolymers with anionic, 41,50 cationic, 51 zwitterionic, 52,53 and neutral [54][55][56] functionality have been synthesized directly in water without post-reaction chemistry.…”