Acid-initiated ring-opening polymerization kinetics

Acheson process, 566 Acid-initiated ring-opening polymerization comparison widi base-initiated process, 79 kinetics, 79-80 mechanism, 79-81 rate retardation by water, 81 relative reactivities of cyclosiloxanes, 79 step-growth process, 79 Acyclic oligosilanes, photochemical transformations, 432/-433/ Acylsilanes... 

Polymerization efficiencies for the initiator systems hexamethylene di-isocyanate and 7V-acetyl caprolactam have been evaluated and the di-isocyanate found to be the more active. Studies on -caprolactam in closed systems have been made and the main polymerization processes for the system, caprolactam, water, and a viscosity stabilizer (acetic acid or butylamine), were evaluated. These are ring-opening polymerizations by hydrolysis, polycondensation of amine and carboxyl ends, and polyaddition of caprolactam to amino end-groups. Apparent activation energies were determined for these main reactions and it was suggested that addition occurred in preference to polycondensation. Post-polymerization of E-caprolactam under reduced pressure in the presence of water vapour and phosphoric acid has been kinetically analysed and the rate of increase of the degree of polymerization was derived theoretically as a function of reaction variables. 

It was demonstrated that DBO polymerizes with Lewis acids as initiators. BF3 OEt SbCl5 and PFS were used and the best results were obtained with PFS however, no systematic studies of the kinetics of polymerization or molecular weights have been published yet. The stereochemistry of DBO polymerization was investigated in detail, and it was shown that DBO polymerizes exclusively through opening of the 5-membered ring ... 

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