Doetze Jakob Sikkema

Design, synthesis and properties of a novel rigid rod polymer, PIPD or 'M5': high modulus and tenacity fibres with substantial compressive strength

Abstract A rigid rod polymer with strong hydrogen bonds between the polymer chains was found in polypyridobisimidazole based on 2,3,5,6-tetraaminopyridine and 2,5-dihydroxyterephthalic acid (D. J. Sikkema and V. Lishinsky, WO 94/25506). The strong interchain forces translate into the highest compressive strength found in polymer fibres by far, and the polarity of the polymer seems to contribute to easy adhesion in advanced composite manufacture. The modulus and tenacity are as expected for a rigid rod polymer in the general class of the earlier PBZT and PBO fibres. Download : Download full-size image

One Pot Synthesis of 2,6-Dichloro-3,5-dicyanopyridine from Aliphatic Precursors

Abstract Malononitrile is condensed with triethyl orthoformate in the presence of pyridine; the mixture is acidified with HCI gas and after addition of further pyridime. HCI diazotised to form 2,6-dichloro-3,5-dicyanopyridine in a convenient, high yield process.