Thermal decomposition products of copoly(arylene ether sulfone)s characterized by direct pyrolysis mass spectrometry Filippo Samperi a, * , Concetto Puglisi a , Tiziana Ferreri a , Rosario Messina a , Gianluca Cicala b , Antonino Recca b , Carmelo Luca Restuccia b , Andrea Scamporrino b a Institute of Chemistry and Technology of Polymers, CNR, Viale A. Doria 6, 95125 Catania, Italy b Department of Chemistry and Physics Methodologies for Engineering (DMFCI), University of Catania, Viale A. Doria, 6 95125 Catania, Italy Received 18 January 2007; received in revised form 7 March 2007; accepted 19 March 2007 Available online 28 March 2007 Abstract Pyrolysis products with mass of up to 850 Da were detected by direct pyrolysis mass spectrometric (DPMS) analysis of a series of copoly(ar- ylene ether sulfone)s (PESePPO) synthesized by nucleophilic condensation of either 4,4 0 -dichlorodiphenylsulfone (CDPS) or 4,4 0 -bis-(4-chlor- ophenyl sulfonyl) biphenyl (long chain dichloride, LCDC) with different molar ratios of hydroquinone (HQ) or dihydroxydiphenylsulfone (HDPS). Pyrolysis products retaining the repeating units of the initial copolymers were formed at temperatures ranging from 420  C to 470  C (near the initial decomposition temperature). At temperatures higher than 450  C were observed products containing biphenyl units, formed by the elimination process of SO 2 from diphenyl sulfone bridges. Products having biphenyl and dibenzofuran moieties were detected in the mass spectra recorded at temperatures above 550  C. These units were formed by loss of hydrogen atom from diphenyl ether bridges. Although the EI (18 eV) mass spectra of the pyrolysis products of the samples investigated were very similar, it was found that the relative intensity of some ions reflects the molar composition of the copolymers analysed. Cyclic and linear oligomers with very low molecular mass, present in the crude copolymers, were also detected by DPMS. Thermogravimetric analysis also showed their excellent thermal stability below 400  C. It indicates that the copolymers yield a char residue of 40e45% at 800  C, which increases with the PPO mole fraction in the samples. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Copoly(arylene ether sulfone)s; PESePPO; Pyrolysis products; DPMS 1. Introduction Aromatic thermoplastic poly(ether-sulfone)s (PES) have reached a remarkable scientific and industrial interests owing to their excellent mechanical, chemical and thermal stabilities [1e3]. This class of polymers have found application as adhe- sives for metal-to-metal bonds [2], membranes for separating gases and solids from solution [3], matrices for fibre rein- forced composites and as toughening agents for thermosetting resins [4e6]. It has been reported in the literature that a wide spectrum of thermal, chemical and mechanical properties and also morphological behaviour, can be obtained by varying the type of monomer units in the corresponding copolymers, their molar composition and therefore the ratio between the ether and sulfone and/or other links (e.g. ketone) [7]. In recent years, the use of some low molecular weight random copoly- (ether-sulfone)s as toughening agents has been proposed [7e10] to overcome the miscibility problems encountered [6,8] with some commercial formulations, which were based on the addition of high molecular weight PES. The random copoly(ether-sulfone)s were shown to be efficient modifiers to obtain homogeneous morphology because of the higher flexibil- ity of their chains, due to the presence of arylene ether- ether-sulfone (EES) units, in which a larger number of ether links than that in PES is present. Some random copoly(ether- sulfone)s (referred as PESePPO) containing p-phenylene * Corresponding author. Tel.: þ39 95 339926; fax: þ39 95 221541. E-mail address: fsamperi@unict.it (F. Samperi). 0141-3910/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymdegradstab.2007.03.015 Polymer Degradation and Stability 92 (2007) 1304e1315 www.elsevier.com/locate/polydegstab