SYNOPSISA comprehensive I3C-NMR method for the analysis of composition in the most common commercial polyethylene copolymers has been established. The method covers ethene copolymers with propene, butene-1, hexene-1, octene-1, and 4-methyl pentene-1 in the composition range of 1-10 mol %. The chemical shift assignments and TI values of the resonances of the copolymers are presented. Results of precision studies and interlaboratory analyses showed that the molar composition could be determined with a relative precision at 2a of about 6%. This method is being proposed to ASTM as Method X70-8605-2.

Star polymers with reactive isocyanate end groups were prepared via the end capping of hydroxy‐terminated star polyether polyols with toluene diisocyanate (TDI; 80% = 2,4 TDI, 20% = 2,6 TDI). The multifunctional polyols and TDI were reacted in bulk without a catalyst. This procedure was optimal in regard to the product yield, minimizing unfavorable coupling side reactions and avoiding crosslinking reactions. The experimental results were based on theoretical studies of the reaction kinetics. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2555–2565, 2000

The structures and stereochemistry of the trimers, containing two acrylonitrile units and one styrene unit (AnzS), produced during the spontaneous copolymerization of styrene (S) and acrylonitrile (An) were determined using NMR, 13C NMR, and X-ray crystallography. High-pressure liquid chromatographic (HPLC) conditions are described for the separation of the oligomers. One of the AngS stereoisomers was obtained as a pure crystalline compound. Its thermochemistry was studied to gain insight into its origin. This information together with the results of other experiments (the effect of acid on SAn polymerization kinetics and the ability to spontaneously copolymerize 2-vinylmesitylene and acrylonitrile) indicates that the "Mayo mechanism" is not responsible for initiation of SAn copolymerization.

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