Determination of the molecular weight distribution of linear and branched polyvinyltrimethylsilanes

Poly(vinyl trimethylsilane) and block copolymers of vinyl trimethylsilane with isoprene: Anionic polymerization, morphology and gas transport properties

“…All molecular characteristics are summarized in Table 1. As observed in the table but is also mentioned in the literature [13] the polydispersity index (PDI) is higher than expected for this type of polymerization (1.4-2 instead of polydispersities close to 1-1.1). Higher molecular weight PVTMS studied by Nametkin et al [13] contain to a small extent (2-3%) slightly branched architectures, leading to diffusion into the columns and broader polydispersities.…”

“…As observed in the table but is also mentioned in the literature [13] the polydispersity index (PDI) is higher than expected for this type of polymerization (1.4-2 instead of polydispersities close to 1-1.1). Higher molecular weight PVTMS studied by Nametkin et al [13] contain to a small extent (2-3%) slightly branched architectures, leading to diffusion into the columns and broader polydispersities. Moreover the n-BuLi intitated polymers are considered to self terminate at low conversion which would appear in the molecular weight distribution curve as a low molecular tail [13].…”

“…Higher molecular weight PVTMS studied by Nametkin et al [13] contain to a small extent (2-3%) slightly branched architectures, leading to diffusion into the columns and broader polydispersities. Moreover the n-BuLi intitated polymers are considered to self terminate at low conversion which would appear in the molecular weight distribution curve as a low molecular tail [13]. Weight averaged molecular weights were confirmed by static light scattering in THF solution at 30°C and the difference found was close to 10% from the ones calculated by GPC, thus the deviation did not exceed the error of the molecular weight determination by the GPC method.…”

“…The molecular characterization of the samples proved the successful synthesis of all three types of polymeric materials. The homopolymerization of PVTMS was known long ago [13], but according to our knowledge the sequential and simultaneous copolymerization with isoprene has never been reported in the literature. In the case of copolymerization with isoprene its actual percentage was calculated from 1 H-NMR results.…”

“…Isoprene was inserted into the polymerization reactor and left to complete conversion according to the kinetics proposed by Bywater for the polymerization of isoprene with n-BuLi in cyclohexane. [12] The addition of VTMS was achieved by distillation into the reactor, and the reaction was left to complete for six days at 35°C [13]. During the polymerization reaction there were no samples removed and after the completion the polymer was precipitated into excess of methanol only once.…”