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Mechanism Studies of LCP Synthesis
C.S. Marvel Laboratories, Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
* Author to whom correspondence should be addressed.
Received: 15 February 2011; in revised form: 24 March 2011 / Accepted: 22 April 2011 / Published: 4 May 2011
Abstract: 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.
Keywords: Liquid Crystal Polymer; 4-hydroxybenzoic acid; polycondensation; phenolysis; acidolysis
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MDPI and ACS Style
Buyle Padias, A.; Hall, Jr., H.K. Mechanism Studies of LCP Synthesis. Polymers 2011, 3, 833-845.
Buyle Padias A, Hall, Jr. HK. Mechanism Studies of LCP Synthesis. Polymers. 2011; 3(2):833-845.
Buyle Padias, Anne; Hall, Jr., Henry K. 2011. "Mechanism Studies of LCP Synthesis." Polymers 3, no. 2: 833-845.