Gel formation in atom transfer radical polymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate

Abstract

Copolymers of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMAEMA) and ethylene glycol dimethacrylate (EGDMA) were synthesized via atom transfer radical polymerization using ethyl 2‐bromoisobutyrate as the initiator, Cu(I)Br as the catalyst, and 1,1,4,7,10,10‐hexamethyltriethylene tetramine as the ligand. At low crosslinker levels, the polymerizations followed the first‐order kinetics. However, when the crosslinker level was above 10 mol %, the ln([M]0/[M]) versus time curves showed deceleration at medium conversions because of the higher reactivity of EGDMA than that of DMAEMA. An acceleration at high conversions was also observed and probably caused by the diffusion limitations of catalyst/ligand complex in the polymer network. The hydrogels were characterized by swelling experiments, and the sol polymers were characterized by the size exclusion chromatographic technique to determine the number‐average molecular weight and polydispersity. The gel data were analyzed and, via a comparison to Flory's gelation theory, found to be more homogeneous than similar hydrogels prepared by conventional free‐radical polymerization methods. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3780–3788, 2001

Novel Biodegradable Adaptive Hydrogels: Controlled Synthesis and Full Characterization of the Amphiphilic Co‐Networks

“…The cross-linking density 1 was calculated from the plot in Figure 10 and equals 0.026, which is very close to the value of 0.029 determined by Hunkeler et al [19] for PDMAEMA-based networks prepared by ATRP using ethylene glycol dimethacrylate as cross-linking agent. Notably, these values differ only by a factor of three compared to Florys equation (1 = 0.01), which is quite satisfying taking into account the difference of several orders of magnitude usually observed for conventional FRP.…”

“…More recently, atom-transfer radical polymerization (ATRP) has also been used for the synthesis of cross-linked polymers. Jiang et al reported a one-step gelation process involving the ATRP of either N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) with ethyleneglycol dimethacrylate (EGDMA) cross-linker, [19] or methyl methacrylate (MMA) with EGDMA [20] for which they evidenced an autoacceleration rate at high conversion due to diffusion-controlled radical deactivation. Zhu et al [21,22] demonstrated that ATRP leads to more homogeneous networks than those produced by FRP.…”

“…Such a high propagation rate and poor chain relaxation are responsible for the formation of heterogeneous networks with highly crosslinked microdomains and extra macromolecular entanglements restricting chain mobility and swelling. [19] In contrast to the FRP process, the ATRP mechanism is known to allow the synthesis of linear polymer chain with controlled molecular weight and narrow polydispersity index. In the context of this research, it was of great interest to evaluate the influence of such a "living"/controlled mechanism on the cross-linking reaction and more particularly, on the polymethacrylate backbone.…”

Kinetic Behavior of Atom Transfer Radical Polymerization of Dimethacrylates

“…Recently, the syntheses of crosslinked polymers with well-controlled network structures by controlled/living radical polymerization methods have been reported. [31][32][33] The mechanism and kinetics in a network forming ATRP system may be very different from those in linear and/or branching ATRP systems since the development of a threedimensional network restricts the mobility of reactive species such as monomers and catalyst/ligand complexes. From a fundamental viewpoint, our knowledge about the polymerization behavior and kinetics in network forming ATRP systems is severely lacking.…”

Copolymerization Kinetics of Styrene and Divinylbenzene in the Presence of S‐Thiobenzoyl Thioglycolic Acid as RAFT Agent

“…It would be desirable to have a synthetic route to synthesize homogeneous polymer networks using free radical technology. This goal may be achieved by copolymerizing vinyl and divinyl monomers in the presence of CLRP controllers [6].The production of polymer networks by controlled/living radical copolymerization (CLRC) techniques, including the copolymerization of vinyl/divinyl monomers, has already been addressed in the literature for the cases of INIFERTER [16][17][18][19], ATRP [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], NMRP [6,[37][38][39][40][41][42][43][44][45][46][47], and RAFT [48][49][50][51][52][53][54][55][56][57][58][59][60]. A short review of these studie...…”