Investigation of redox initiators for free radical frontal polymerization

Background: The reaction temperature for frontal polymerization (FP) initiated by redox initiators can be greatly decreased compared with FP initiated by peroxide initiator and disulfide initiator.We report the synthesis of poly(hydroxyethyl acrylate)s via free radical FP using benzoyl peroxide (BPO)/N,N-dimethylaniline (DMA) and ammonium persulfate (APS)/N,N,N',N'-tetramethylethylenediamine (TMEDA) couples as redox initiators at ambient pressure. Results: The results show that unlike the phenomenon of bubbles and 'fingers' when using BPO alone, a self-sustaining and stable front can be obtained when the [DMA]/[BPO] ratio is higher than 1 (mol/mol). A slight increase of the DMA (or TMEDA) reductant concentration causes amarked decrease of front temperature to 53 °C (or 61°C). Conclusion: We investigated the effects of the ratio of the oxidant to the reductant and the initiator and monomer concentrations on certain parameters of FP: formation of bubbles, front velocity and front temperature. This opens the way to the potential development of FP using more appropriatemonomers with low boiling points.