e-Polymers 2004, no. 011. ISSN 1618-7229 http://www.e-polymers.org Characterization of an isophorone-based polyisocyanate Fabrice Burel 1 , Adeline Feldman 1 , Corinne Loutelier-Bourhis 2 , Claude Bunel 1 * 1 Laboratoire de Matériaux Macromoléculaires, UMR CNRS 6522, PBM, INSA de Rouen, BP 08, place Emile Blondel, 76131 Mont-Saint-Aignan cedex, France; Fax 33-02.35.52.84.46; fabrice.burel@insa-rouen.fr, claude.bunel@insa-rouen.fr 2 Laboratoire de Spectrométrie de Masse Bio-Organique, UMR CNRS 6014, Université de Rouen, 76821 Mont-Saint-Aignan cedex, France (Received: February 3, 2004; published: February 25, 2004) Abstract: After chemical modification with methanol, a polyisocyanate based on the isocyanurate of isophorone diisocyanate was analysed. MALDI-TOF MS and size- exclusion chromatography were chosen and indirectly coupled to identify and quantify the different species. While, as expected, the isocyanate trimer and penta- mer are the two main components, homologues until the tridecamer could be identified with MS. Moreover, the isocyanurate cycle occurs preferentially on the primary isocyanate group. According to the calculated composition, a number- average molecular weight of 775 and a number-average isocyanate functionality of 3,24 were determined. Introduction Polyurethane elastomers are a class of polymeric materials showing a wide range of interesting physical and mechanical properties such as tensile properties, thermal behaviour, hardness, and surface characteristics. These properties are essentially linked to the nature of the polyol (polyester, polyether, …) and of the isocyanate. In the coating industry both aromatic and aliphatic isocyanates are used. Nevertheless, compared to the aromatic structures, coatings based on aliphatic isocyanate exhibit excellent light and weather stability and are, therefore, usually used for outdoor appli- cations. Among the most common aliphatic isocyanates are hexamethylene diiso- cyanate (HDI) and isophorone diisocyanate (IPDI). The major problem encountered with these products is their high volatility, which enhances the inherent toxicity of the isocyanate group. To avoid this drawback, the coating industry works with trimerized diisocyanates leading to biuret or isocyanurate forms (Scheme 1). Both are less toxic and enhance thermal properties compared to the corresponding diisocyanates. However, the trimerization processes used to obtain biuret and isocyanurate products often yield mixtures of polymeric forms [1]. While IPDI has been previously characterized [2,3], this is not the case for the corre- sponding isocyanurate, in spite of its growing use for outdoor applications. Its charac- terization is, therefore, necessary for a further understanding and optimization of the isocyanurate - alcohol reaction. In this paper, an IPDI isocyanurate is studied with a combination of analytical techniques including size-exclusion chromatography (SEC), 1