Mechanism Studies of LCP Synthesis

Polymers

Anne Buyle Padias¹ 

[1] C.S. Marvel Laboratories, Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA; E-Mail

关键词: Liquid Crystal Polymer;    4-hydroxybenzoic acid;    polycondensation;    phenolysis;    acidolysis;   

DOI  :  10.3390/polym3020833

来源: mdpi

【 摘 要 】

The LCP (Liquid Crystal Polymer) known as Vectra is synthesized by acidolysis of 4-hydroxybenzoic acid with 6-hydroxy-2-naphthoic acid. The apparently simple acidolysis mechanism for LCP polycondensation is in fact a complex blend of mechanisms. Kinetics of model reactions and of actual polycondensations followed second-order kinetics and their rate constants were comparable. In the latter stages, ketene loss leads to phenolic ends, while decarboxylation provides phenyl ester ends. Accordingly, the mechanism changes to phenolysis. A quinone methide intermediate may also intervene, as revealed by kinetics studies and MALDI-TOF spectroscopy. Tailor-made matrices and synthesis of alternating well-defined oligomers assisted our studies. Nucleophilic aromatic substitutions may play a role, and we speculate on possible chain polycondensation. Esterolysis may be a useful alternative to LCP synthesis. Complications caused by ketene loss can be averted by the use of methoxycarbonyloxy monomers.

【 授权许可】

CC BY   
© 2011 by the authors; licensee MDPI, Basel, Switzerland.