Full Paper Macromolecular Chemistry and Physics (1 of 7) 1700145 © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com DOI: 10.1002/macp.201700145 4-Styrenesulfonyl-(2-methyl)aziridine: The First Bivalent Aziridine-Monomer for Anionic and Radical Polymerization Tassilo Gleede, Elisabeth Rieger, Tatjana Homann-Müller, Frederik R. Wurm* 4-Styrenesulfonyl-(2-methyl)aziridine (StMAz), the first orthogonal aziridine monomer, for both anionic ring-opening and radical polymerization is presented. Both polymerization path- ways are accessible without using protective groups. Aza-anionic ring-opening polymerization (A-AROP) of StMAz and other methyl-aziridine derivatives provide multifunctional polyaziri- dines. Molecular weights between 3000 and 13 000 g mol -1 are obtained with low molecular weight dispersities (Ð = 1.1). The amount of vinyl groups in linear polyaziridines from A-AROP depends on the monomer/comonomer ratio. The vinyl groups of P(StMAz)- homo- or copoly- mers are entirely convertible by thiol-ene addition. This allows modification with multiple functional groups. Free radical polymerization of StMAz leads to polyalkylenes with aziridine side groups, which are known to be efficiently addressable via nucleophiles. Polysulfonamides still belong to a rather new class of polymers accessible by anionic polymerization. Enlarging the scope of postpolymerization modifications on polyaziridines/-sulfonamides is important for further macro- molecular architectures. The aziridine and the vinyl group are combined to develop the first orthogonal monomer for aza- anionic polymerization and radical polymerization. T. Gleede, E. Rieger, T. Homann-Müller, F. R. Wurm Max-Planck-Institut für Polymerforschung (MPIP) Ackermannweg 10, 55128 Mainz, Germany E-mail: wurm@mpip-mainz.mpg.de The ORCID identifcation number(s) for the author(s) of this article can be found under https://doi.org/10.1002/ macp.201700145. allows fast access to a variety of highly functional polymer materials based on various monomers. On the other side, living ionic polymerization allows the highest control over molecular weights and distributions. [6,7] Ionic polymeriza- tions of epoxides or aziridines can be used to prepare poly- ethers and polyamines, but most functional groups need to be protected. An outstanding class of monomers, the so- called “bivalent or orthogonal monomers,” is polymerized chemoselectively by different mechanisms while main- taining the other group. To date, only few of such mono- mers have been reported. [8–10] Aziridinyl ethyl methacrylate (AEMA), for example, can be selectively polymerized by radical or carbanionic polymerization of the acrylate and by cationic polymeri- zation of the aziridine ring, functional polyamines are obtained. AEMA represents to the best of our knowledge the first orthogonal aziridine-containing monomer. [8] However, anionic polymerization of the aziridine cannot 1. Introduction Nitrogen-containing polymers (N-polymers) are often favored for drug delivery issues regarding cell targeting, like gene delivery studies show. [1,2] Additionally, they are applied in water refinery [3,4] and can serve as direct cata- lysts by stabilizing transition metals. [5] To fulfill the goals of current scientific challenges, functionalizable groups at N-polymers are essential for fine adjustment of polymer properties. Radical polymerization of vinyl monomers Macromol. Chem. Phys. 2017, DOI: 10.1002/macp.201700145