No abstract

No abstract

t-Butylacetylene was polymerized by MoC1 5 and WC16 as catalysts at 30oC or ooc in hydrocarbon and halogenated hydrocarbon solvents. Poly(t-butylacetylene) was obtained in high yield especially with MoC1 5 , and the highest polymer molecular weight exceeded 3 x 10 5 . The following relationship was obtained between the viscosity and molecular weight: [IJ]=I0-5 · 12 M/.Dl. The polymer was soluble in nonpolar solvents, particularly in aliphatic hydrocarbons. The infrared (IR), 1 H nuclear magnetic resonance (NMR), and 13 C NMR spectra supported the expected polymer structure, fCH=C(t-BuHn· A pair of doublets were observed for the methyl carbon in the 13 C NMR of polymer, making possible an evaluation of geometric structure.

Living polymerization of isobutyl vinyl ether (IBVE) was achieved with an equimolar mixture of hydrogen iodide (HI) and iodine in n-hexane at -15 eC to give nearly monodisperse poly (IBVE). The number-average molecular weight (Af") of the polymers increased in direct proportion to monomer conversion and to the reciprocal of the initial HI concentration. Their molecular weight distribution (MWD) remained nearly monodisperse (Mw/Mb 5 1.1) throughout the reaction. The polymerizations in other solvents (CH2C12 and toluene), in contrast, were not living and yielded polymers having broader MWD (Afw/Mn = 1.4-2.0), the Mn of which did not increase with conversion. Iodine ¿one could not effect a truly living IBVE polymerization in n-hexane; the Af" of the product polymers increased only slightly with conversion. The polymerization by HI alone in n-hexane was much slower than that by the HI/I2 initiating system. Interestingly, addition of iodine to a quiescent mixture of HI and IBVE led to a rapid polymerization that yielded nearly monodisperse polymers.

No abstract