MMA polymerization at

The importance of the cage reaction increases according to the viscosity of the reaction medium. This contributes to a decrease in initiator efficiency with conversion. 15 1 155 Stickler and Dumont156 determined the initiator efficiency during bulk MMA polymerization at high conversions ca 80%) to be in the range 0.1-0.2 depending on the polymerization temperature. The main initiator-derived byproduct was phenyl benzoate. 

Figure 5.3 Conversion-time profile for bulk MMA polymerization at 50 °C with AIBN initiator illustrating the three conversion regimes. Data are taken from...

A number of other chemistries which involve C-O bond cleavage have been reported.226 22 Druliner226 has reported on systems where NCO, 112, 113 or related species is the persistent radical. Homolysis rates for these systems were stated to he suitable for MMA polymerization at ambient temperature. The use of NCO has also been studied by Grande et al. z most recently for AA polymerization.2 0 Although control during AA homopolymerization was poor the process yielded NCO- terminated PAA that could be used to make PAA-block-PMMA.230... 

TABLE 5. Effect of various ligands on the stereochemistry of the MMA polymerization at —78°C... 

The polymerization of MMA was also examined with the alcohols (precursors). To ensure a fast initiation from the alkyl iodide, we used a tertiary alkyl iodide, CP-I (Figure 1), irrstead of the secondary one, PE-1. All of the mentioned five alcohols and BHA (Figrtre 1) well controlled the MMA polymerization at 80 °C, as the examples in Table 2 illustrate. We are now systematically studying the relatiorrship between the stmctrrre of alcohol and the polydispersity control, which will be reported elsewhere. 

Figure 5 Glass effect - MMA polymerized at 80 °C stops at 95% conversion. Temperature is raised at the end of polymerization to complete the residual 5% monomer. ...

Figure 7 (a) Change of GPC curves with monomer conversion in bulk MMA polymerization at 70 °C and 0.5% AIBN and (b) their calibrated number- and weight-average molecular weights. ... 

Figure 16 Conversion time profile for bulk MMA polymerization at 50 °C with AIBN initiator illustrating the three conversion regimes. Data are taken from Balke, S. T. Hamielec, A. E. J. Appl. Polym. Sci. 1973,17, 905-949. ...

Figure 19 First-order time-conversion plots of MMA polymerization at -20 °C with EIBLi/NBu4 [Al2Et6Br]" in toluene at different concentrations of NBu4+[Al2El6Br]". [EIBLi]o = 0.44 x 10" mol I" [NBu4Br]/ [AIEta] 0.5/1.1 (A), 1.2/2.5 ( ), 6.9/15.0 ( ) moll" and [MMA]o = 0.23 mol I Reprinted with kind permission from the American Chemical Society.

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