Polymers of carbonic acid, 4. Crystalline smectic polyurethanes derived from piperazine or 4,4′‐bipiperidine and diphenols containing aliphatic spacers

• Published in: Die Makromolekulare Chemie
• Main Authors: Kricheldorf, Hans R., Awe, Jens
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1989
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1002/macp.1989.021901023; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fmacp.1989.021901023; https://onlinelibrary.wiley.com/doi/pdf/10.1002/macp.1989.021901023

Abstract 4,4′‐Alkylenedioxydiphenols ( 3a–e ), prepared from α,ω‐dibromoalkanes and hydroquinone, were converted with phosgen to the corresponding dichloroformates 4a–e , which were reacted with piperazine, trans ‐2,5‐dimethylpiperazine or 4,4′‐bipiperidine under the conditions of interfacial condensation. The DSC measurements of polyurethanes derived from 2,5‐dimethylpiperazine displayed one endotherm indicating a normal melting process, whereas the polyurethanes derived from piperazine or 4,4′‐bipiperidine showed a reversible first order phase transition below the melting point. WAXS powder patterns indicate a change between two different smectic modifications. Thermomechanical analyses (penetration method) proved that also the high‐temperature smectic modification is a solid state and not a liquid‐crystalline one.