Synthesis and radical polymerization of bifunctionalized aziridinic methacrylates Marli Luiza Tebaldi de Sordi ⇑ , Eduardo de Oliveira da Silva, Marco Antônio Ceschi, Cesar Liberato Petzhold Instituto de Química, Departamento de Química Orgânica, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil article info Article history: Received 10 September 2010 Received in revised form 14 January 2011 Accepted 27 February 2011 Available online 13 March 2011 Keywords: Aziridine Methacrylate Stability Atom transfer radical polymerization (ATRP) Reversible addition–fragmentation chain transfer (RAFT) abstract The synthesis and controlled radical polymerization of 2-(1-aziridinyl)ethyl methacrylate (AZMA) and (1-phenylaziridin-2-yl)methyl methacrylate (PAZMA), which have two polymerizable groups in their structures, were performed. RAFT polymerization using CPDB as chain transfer agent (CTA) and AIBN as initiator was carried out in bulk and in solution at 60 °C with a good control of the molecular weight. A living behavior was observed for both monomers. ATRP polymerization (CuBr/PMDETA/EBiB) of AZMA led to a crosslinked material. For PAZMA a nonliving behavior in ATRP polymerization was reached, how- ever no crosslink was observed due to higher stability of its aziridine ring. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Aziridines are a compound class containing a three-membered saturated heterocyclic with one nitrogen atom. Due to the combi- nation of Bæyer strain in the three-membered heterocycle and the nucleophilicity of the heteroatom aziridines ring cleavage reac- tions occur under relatively mild acidic conditions [1]. Several methods for the synthesis of aziridines are described in the literature, among them are aziridination of alkenes with chlo- ramine – T using aqueous solution of H 2 O 2 /HBr [2] or Cu(II) [3] Rd(II) catalysts and other conditions [4–6]. Methods as cyclization of amino alcohols have already been described elsewhere [7–10]. The efficiency of these reactions depends on a series of factors, especially, on the substitutes of the reagents [1]. Aziridines can be important as synthetic intermediate in the preparation of phar- maceutical and agrochemical products [11]. The importance of aziridines is also recognized in asymmetric synthesis, where in many cases, the use of chiral ligands and auxiliaries is necessary to improve the efficiency of these synthesis [12]. Another subclass of these compounds are the vinylaziridines, which have been proved to be powerful intermediate for various types of natural products and synthetic compounds [13,14]. Aziridines that have a polymerizable double bond group as sub- stitute make them a unique class of compounds which consists of two different polymerizable groups where it is possible to initiate a polymerization and/or to modify the polymer structure. Such type of bifunctionalized monomers are for example glicidyl methacry- late (GMA) [15] 2,3-epithiopropyl methacrylate (ETMA) [16] (4-maleimidophenyl)oxirane (MAPO) [17] 2-(1-aziridinyl)ethyl methacrylate (AZMA) [18]. Therefore, these compounds can under- go vinyl polymerization under free-radical or ionic conditions, as well as ring-opening polymerization. These functional polymers are of great interest as precursors of graft copolymers, hydrophilic polymers and crosslinked micelles or gels. Therefore can be used as dental adhesives [19] coatings [20] and thermosetting resins [21]. The ionic and radical polymerization of the AZMA has already been described in the literature [18]. Authors have achieved well-defined polymers bearing the aziridine ring by anionic poly- merization with MWD 6 1.07 using a binary initiator system con- sisting of Ph 2 CHK/Et 2 Zn. In addition, crosslinked gels were obtained by the treatment of the poly(AZMA) with adipic acid in THF at room temperature due to aziridine ring opening at the poly- meric chain. Conventional radical polymerization conditions per- formed using AIBN as initiator led to polymers with MWD around 3.8. However, no results about controlled radical polymer- ization of the AZMA have been described. The controlled/living radical polymerization (CRP) techniques have been the most important development in polymer synthesis in the last 10 years [22]. Among these controlled radical polymer- ization, atom transfer radical polymerization (ATRP) [23–25] and reversible addition–fragmentation chain transfer (RAFT) [26,27] polymerization have become the most popular methods because of their adaptability to a wide range of functional monomers under 1381-5148/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.reactfunctpolym.2011.02.005 ⇑ Corresponding author. Tel.: +55 51 33086285; fax: +55 51 33087304. E-mail address: marli@iq.ufrgs.br (M.L.T. de Sordi). Reactive & Functional Polymers 71 (2011) 648–654 Contents lists available at ScienceDirect Reactive & Functional Polymers journal homepage: www.elsevier.com/locate/react