Macromol. Theory Simul. zyxwvu 4, 935-946 zyxwv (1995) zyxwvu 935 zy On the contribution of covalent and ionic species to the chain growth. Monte Carlo simulations and theoretical considerations Ryszard Szymanski Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 90-363 Lodz, Sienkiewicza 112, Poland (Received: December 19, 1994; revised manuscript of May 2, 1995) SUMMARY: Contributions of the covalent and ionic species to the chain building in cationic reversible polymerizations are analyzed by means of Monte Carlo simulations and by solving the formulated set of equations. The validity of the equation for the contribution of covalent propagation, derived for reversible polymerization with simplifying assumptions, is discussed. It is shown that repeating units incorporated into the chain by covalent propagations are distributed uniformly only when direct monomer insertion into covalent bonds is not possible, or when intramolecular interconversion of covalent and ionic species is very fast in comparison with propagation. Introduction In the previous paper I) the simultaneous propagation of ionic and covalent species in cationic reversible polymerizations of cyclic monomers was discussed. The general scheme of reactions involved is the following (for the sake of simplicity free ions are neglected): zyxwvuts ...- mA + M & ...- mmA kdc ka k,,, ...- mA + M mm+,A- (3) kw ..-m+,A- + M ... kdi Assuming a uniform distribution of the repeating units incorporated into the polymer via different propagation routes (i. e., an equal probability of finding units incorporated by the given type of propagation at any chain position including chain ends) an equation for the contribution of covalent propagation was derived '). This equation has the same form as the corresponding equation for irreversible polymeriza- tion y = zyxwvuts a.(kei + kp,)/(a-(kei + kpc) + (1 - a)kpi) (5) zy 0 1995, Huthig & Wepf Verlag, Zug CCC 1022-1 344/95/$05.00