Memory effects in supramolecular networks of diacids and polyfunctional pyridine derivatives

• Published in: Journal of applied polymer science 2004-06, Vol.92 (5), p.3097-3106
• Main Authors: Wiegel, Kurt N., Griffin, Anselm C., Black, Micah S., Schiraldi, David A.
• Format: Article
• Language: English
• Subjects: Applied sciences; crystallization; Exact sciences and technology; hydrogen bonding; networks; Physicochemistry of polymers; polyesters; Polymer industry, paints, wood; supramolecular; Technology of polymers; transport
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.20351

Highly crosslinked networks were produced through a series of diacids and tetrakis pyridyls. These materials displayed complex crystallization behaviors over multiple heat/cool cycles. The shifting of crystallization behaviors with time in the melt phase seems to indicate that the materials move toward thermodynamically ideal structures. This behavior is suggestive of a type of memory in which the networks remember the morphological structure previous to the melt and improve upon that structure in the next cooling cycle. The network/memory phenomena observed in small molecule diacid/tetrapyridyl systems also appeared to exist when poly(ethylene terephthalate) (PET) polymer was used as the source of carboxylic acid functionalities. The same time‐ dependent behaviors, suggestive of sequential steps toward thermodynamically optimum states, were observed when the PET/tetrapyridyl systems were thermally cycled. It was also observed that complexation of tetrapyridyl with PET brought about a significant change in oxygen gas barrier properties; these changes were opposite to those obtained when covalent crosslinks were introduced into PET. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3097–3106, 2004