Frontal Polymerization of Diurethane Diacrylates ALBERTO MARIANI, 1 STEFANO FIORI, 2 SIMONE BIDALI, 1 VALERIA ALZARI, 3 GIULIO MALUCELLI 4 1 Dipartimento di Chimica, UdR INSTM, Universita ` di Sassari, 07100 Sassari, Italy 2 R&D Department, Condensia Quimica SA, C/ La Cierva 8, 08184 Palau de Plegamans (BCN), Spain 3 Materials Engineering Centre, UdR INSTM, NIPLAB, Universita ` di Perugia, 05100 Terni, Italy 4 Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, and local INSTM Research Unit, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy Received 17 January 2008; accepted 13 February 2008 DOI: 10.1002/pola.22675 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: This work deals with the preparation of poly(urethane acrylates) by using two different polymerization techniques. Namely, the classical batch procedure has been compared with frontal polymerization (FP). A thorough study on the effect of initiator type, concentration, and on the velocity of the front and its maximum tem- perature has been carried out. Moreover, two different synthetic ways have been studied: the one step poly(urethane acrylate) preparation starting directly from 1,6 diisocyanato hexane and 2-hydroxyethyl acrylate, and the two step procedure consist- ing of the synthesis of the corresponding diurethane diacrylate and of its subsequent polymerization. The first method has the advantage of being faster but some caution is necessary due to the excessive heat that is generated if the reaction conditions are not properly chosen. The second approach requires a further step but has the advant- age of being more controlled. DSC analysis did not show any significant difference by comparing the thermal properties of the materials obtained by the two techniques (batch and FP). However, since FP runs are very easy and fast to be performed, FP should be seriously taken into proper account when these materials have to be prepared. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3344–3352, 2008 Keywords: addition polymerization; differential scanning calorimetry (DSC); diure- thane diacrylates; frontal polymerization; initiators; poly(urethane acrylates); radical polymerization INTRODUCTION Diurethane diacrylates (DDs) are a class of monomers widely used in polymer preparations; namely, their reaction with diols or diamines is often preferred for the obtainment of polyur- ethane and polyureas, respectively. 1–4 Prompted by the general interest on these products, we have experimented the use of Fron- tal Polymerization (FP) as alternative approach for the synthesis of poly(urethane acrylates). FP is a technique exploiting the heat released during the polymerization reaction to promote a self-sustaining front which travels along the reactor by converting monomer into polymer. In principle, once reached a steady state, FP could propagate indefinitely. FP was initially investigated by Chechilo et al., 5 and lately extensively studied by Pojman Correspondence to: A. Mariani (E-mail: mariani@uniss.it) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 46, 3344–3352 (2008) V V C 2008 Wiley Periodicals, Inc. 3344