Melt Transesterification of Bisphenol Acetophenone– Polycarbonate: A Kinetic Study C. Godinez, L. J. Lozano Department of Chemical and Environmental Engineering, Polytechnic University of Cartagena, 30202 Cartagena (Murcia), Spain Received 30 May 2006; accepted 14 September 2006 DOI 10.1002/app.25507 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: This article deals with the development of kinetic parameters for bisphenol acetophenone–polycarbon- ate made by melt transesterification with diphenyl carbon- ate. The understanding of the influence of borosilicate glass of the reactor construction materials on the accuracy of the kinetic data is reported. During the development of analyti- cal methods, the use of high performance liquid chromatog- raphy-mass spectrometry (HPLC-MS) was proven to be a valid tool to determine the oligomers existing in the reaction mixture. Accurate kinetics parameters were obtained by elimination of the interference of the construction materials. We provide the rate expressions, kinetic parameters [for- ward reaction frequency factor ¼ 2.456  10 13 6 0.01 (cm 3 / mol) 2 /min, forward reaction activation energy ¼ 45.69 6 0.2 kJ/mol, reverse reaction frequency factor ¼ 2.068  10 14 6 0.01 (cm 3 /mol) 2 /min, and reverse reaction activation energy ¼ 56.37 6 0.1 kJ/mol], and equilibrium constants at various temperatures. Ó 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4072–4079, 2007 Key words: activation energy; kinetics (polym.); modeling; polycondensation; step-growth polymerization INTRODUCTION The polycarbonate (PC) homopolymer based in bisphenol A (BPA) is commonly used in optical quality disk applications as the data matrix due to its favorable mechanical and optical properties. A lot of the current work has evolved around BPA PC, and therefore, its optical behavior is well under- stood. 1–6 To date, only two commercial production methods have been demonstrated to produce high quality PCs while remaining economically feasible. These processes are the two-phase interfacial process and the melt transesterification process. The transes- terification method offers many advantages for the manufacture of PCs because the absence of solvents avoid solubility issues and eliminates the need for solvent separation–recycling loops and the unreacted monomers are always at trace levels (<1000 ppm) so that they can be easily degassed in the extruder, which enables direct pelletization right after the reaction. However, fundamental studies of step copolymer- ization in the open literature are far less numerous than those on chain copolymerization. Although a lot of work has been done on the synthesis side of the problem, little quantitative kinetic data of copo- lycondensation has been reported (Mackey et al., 7 Lopez-Serrano et al., 8 Han, 9 Kim et al., 10 and Lyoo et al. 11 ). On top of that, some of the limitations of these earlier kinetic works laid in the accuracy of the experimental methods available, especially regarding the careful definition and control of the reaction con- ditions (e.g., monomer purity, catalyst addition and sampling, influence of construction materials on kinetics, temperature constraints by the boiling point of phenol, accurate reaction startup). In this study, the transesterification of bisphenol acetophenone (BisAP) with diphenyl carbonate (DPC) was examined under a kinetic perspective, and the kinetic parameters for the BisAP–PC homopolymer were derived. These results were used as a previous step for determination of the kinetics of the BPA– BisAP–DPC system, which will be reported in a fu- ture article. BisAP was selected due to its chem- ical similarity with BPA and also because some authors 1,12,13 have claimed that it could reduce the intrinsic birefringence of BPA homopolycarbonate. In addition to the kinetic information, the values for the equilibrium constant were readily available. The equilibrium constant for this particular reaction was of primary importance because reversible polycon- densation reactions can only achieve high conver- sions if the equilibrium is shifted byproduct re- moval. This information is a crucial parameter for the optimum design and operating conditions of fur- ther copolymerization processes. Correspondence to: C. Godinez (carlos.godinez@upct.es). Contract grant sponsor: Fundacio ´n Se ´neca, Government of the Region of Murcia; contract grant number: PPC/ 01445/03. Journal of Applied Polymer Science, Vol. 103, 4072–4079 (2007) V V C 2006 Wiley Periodicals, Inc.