Copolyperoxides of 2-(acetoacetoxy)ethyl methacrylate with methyl methacrylate and styrene; Synthesis, characterization, thermal analysis, and reactivity ratios Sunirmal Pal a , Balaraju Banoth a , Goli Rahithya a , Ashish Dhawan b , Priyadarsi De a, * a Polymer Research Centre, Department of Chemical Sciences, Indian Institute of Science Education and Research e Kolkata, PO: BCKV Campus Main Office, Mohanpur 741252, Nadia, West Bengal, India b Center for Advanced Materials, Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA article info Article history: Received 16 February 2012 Received in revised form 2 April 2012 Accepted 11 April 2012 Available online 20 April 2012 Keywords: Oxidative polymerization Copolyperoxides Reactivity ratios abstract Copolyperoxides of 2-(acetoacetoxy)ethyl methacrylate (AEMA) with styrene (St) and methyl methac- rylate (MMA) of different compositions have been synthesized in the presence of 2,2 0 -azobisisobutyr- onitrile as a free radical initiator under 100 psi oxygen pressure at 50  C. The rates of oxidative copolymerization reactions are determined from the oxygen consumption (Dp) against time plot. Highly exothermic thermal degradations of these copolyperoxides are studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and degradation products have been charac- terised by electron-impact mass spectroscopy (EI-MS). The NMR spectroscopy and EI-MS analysis confirm the alternating peroxy bonds in the main chain. The monomer reactivity ratios are computed by the FinemaneRoss and KeleneTüdös methods, using compositions obtained from 1 H and 13 C NMR analysis. These copolymers can potentially be used as polymeric initiators for the radical polymerization of vinyl monomers, autocombustible fuel. Also, the b-carbonyl moieties along the side chain of the copolyperoxides can be utilized to prepare degradable polyperoxideemetal complexes. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Polymerization of vinyl monomers in the presence of oxygen is known as oxidative polymerization, which produces alternating copolymers (vinyl polyperoxides) of vinyl monomer and molecular oxygen [1]. Vinyl polyperoxides are an important class of polymer due to their interesting physico-chemical properties such as highly exothermic degradation, in contrast to common polymers which usually degrade endothermically [2]. Most recently, radical alter- nating copolymerization of 1,3-diene monomers with an atmo- spheric oxygen pressure has been carried out to prepare polymeric peroxides [3]. Solid-state copolymerizations of dibenzofulvene [4], 7,7,8,8-tetrakis (ethoxycarbonyl) quinodimethane and related monomers [5] with oxygen have been carried out to afford alter- nating copolymers consisting repeating peroxy units in the polymer main chain. This class of polymers are rapidly gaining their importance as coatings [6], dismantlable adhesion [7], polymeric initiators for the radical polymerization of vinyl monomers [8], autocombustible fuel [2], etc. Although polyperoxides are known [9] since 1922’s, very little work has been done to under- stand the role of oxygen during oxidative copolymerization of two monomers. The oxidation of two vinyl monomers could be considered as a special case of terpolymerization, where the monomers (M) do not to homopolymerize. The uniqueness of this system is that it approximates to a binary copolymerization system in terms of MO $ 2 units. The rate of polymerization may then be explained in terms of the copolymerization equation and reactivity ratios [10,11]. The incorporation of metal binding sites into polymers leads to advanced materials due to the combination of physical, chemical, and structural properties provided by the two components. The complexation of metal ions with polymer chains containing ligand groups can be achieved either along the polymer main chain [12] or as side group functionalities [13]. The homo- and copolymer of 2- (acetoacetoxy)ethyl methacrylate (AEMA) are interesting materials, due to the presence of b-carbonyl moieties along the side chain, in which the b-dicarbonyl compounds have high affinity towards metal and metal ions [14]. In addition, homopolymers of AEMA were found to self-assemble into a hierarchical superstructure of double-stranded helical tubes [15], due to the establishment of hydrogen bridges between adjacent acetoacetoxy groups and compensation of dipole moments. The b-carbonyl moieties, act as strong bidentate ligands, in the PAEMA-based polymers can be coordinated to a wide range of metal ions with different geometries and oxidation states. These kinds of polymers have great potential * Corresponding author. Tel.: þ91 9674629345; fax: þ91 33 25873020. E-mail address: p_de@iiserkol.ac.in (P. De). Contents lists available at SciVerse ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer 0032-3861/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymer.2012.04.013 Polymer 53 (2012) 2583e2590