Investigation on the atom transfer nitroxide radical polymerization (ATNRP) mechanism and its versatile applications for bimodal polymers

Abstract

Abstract The atom transfer nitroxide radical polymerization (ATNRP) was developed based on the synergistically happened nitroxide radical coupling (NRC) reaction, atom transfer radical polymerization (ATRP) and nitroxide mediated radical polymerization (NMRP) procedures. The ATNRP of styrene (St) and tert-butyl acrylate (tBA) monomers were systematically studied at different temperature with various molar ratio of [HO-TEMPO]0/[EBiB]0. In the case of St, both ATRP and NMRP can be combined into an ATNRP technique, while the polymerization rate was lowered with the increase of [HO-TEMPO]0/[EBiB]0. With the increase of temperature, the polymerization showed an increased polymerization rate. Alternatively, in the case of tBA, with the addition of HO-TMEPO agent, partial PtBA was terminated by the side reactions of H-abstraction or disproportionation. The remained PtBA was still functionalized with bromide group, and the ATRP can be still continued for a bimodal PtBA. Finally, the resulted PS or PtBA can be further cross-chain-extended by tBA or St, and the bimodal diblock copolymers can be generated. The compositions of the obtained bimodal homopolymer or diblock copolymer can be well controlled by the amount of [HO-TEMPO]0/[EBiB]0.