Synthesis of anthracene end-capped poly(methyl methacrylate)s via atom transfer radical polymerization and its kinetic analyses

The synthesis of anthracene end-capped poly(Me methacrylate)s via atom transfer radical polymn. (ATRP) and the kinetic analyses thereof are reported. Me methacrylate was polymd. in toluene at 90 DegC (or 60 DegC) via ATRP using 9-anthracene-methyl-2-bromo-isobutyrate as the initiator and CuBr/N-(n-hexyl)pyridylmethanimine as the catalyst. Anthracene end-capped polymers with predetd. mol. wts. and low polydispersity (PDI <1.3) were obtained and characterized by 1H NMR and UV-vis. The initiator and Cu(I) concns., initially added Cu(II) concn., and reaction temp. of the ATRP system have a decisive effect on the kinetics of the reaction. When the initiator and Cu(I) concns. or the reaction temp. are relatively high, or the initially added Cu(II) concn. is relatively low, and consequently the radical concn. in the system is relatively high, the kinetics of the polymn. fits Fischer's equation (ln([M]0/[M]) ~ t2/3). On the other hand, Matyjaszewski's equation (ln([M]0/[M]) ~ t) can be fitted quite well when the initiator and Cu(I) concns. or the reaction temp. are so low or the initially added Cu(II) concn. becomes so high that radical termination is negligible. This kinetic transition is of great importance for better understanding the mechanism of ATRP. The equil. and termination consts. (Keq and kt) for the studied ATRP system at 90 DegC are 9.1 * 10-8 and 1.3 * 108 M-1 s-1, resp. The exptl. evidence for Fischer's theor. derived threshold Cu(II) concn. for the kinetic transition, i.e., [Cu(II)]0,t = (3Keq[RX]0[Cu(I)]0kt/kp)1/2, is provided. [on SciFinder (R)]