Propagation rate coefficient of vinyl neo-decanoate by pulsed laser polymerization

The propagation rate coefficient (k(p)) for vinyl neo-decanoate has been measured by pulsed laser polymerization (PLP) over the range -21 to +21 degrees C. The Mark-Houwink-Sakaruda constants required for GPC analysis were obtained using size-exclusion chromatography with an on-line viscosity detector, whose analysis required careful quantification of the uncertainties. The data, which satisfy various consistency tests for PLP (invariance of k(p) to laser pulse frequency, etc.), fit the relation k(p) (dm(3) mol(-1) s(-1)) = 10(7.31) exp(-22.2 kJ mol(-1)/RT); the joint confidence region for these Arrhenius parameters is also given. These Arrhenius parameters are close to those for vinyl acetate [10(7.16) exp(-20.7 kJ mol(-1)/RT)]; the small differences between these Arrhenius parameters are, however, statistically significant at the 95% confidence limit. The vinyl neo-decanoate used is actually a mixture of isomers: CH2=CHOCOCR1R2CH3, where the total number of carbons in R-1 and R-2 is 7; however, theory suggests that the k(p) values for all these isomers should be very similar and polymerization of the mixture can be treated as a homopolymerization with a k(p) equal to the average k(p).