Intramolecular hydrogen bonding and calixarene-like structures in p-cresol/formaldehyde resins |
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Authors: | P. Opaprakasit A. Scaroni P. Painter |
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Affiliation: | The Energy Institute, Penn State University, University Park, PA 16802, USA |
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Abstract: | The nature of the strong hydrogen bonds found in p-cresol/formaldehyde (PCF) resins, compared to ordinary phenolic compounds, is studied. The evidence from FTIR spectroscopy indicates that this strong interaction is due to intramolecular hydrogen bonding from “calixarene-like” structures. The formation of this structure in PCF is enabled by its “linear” (all-ortho-linkage) structure, which is not present in branched resins. Additionally, a transition is observed at around 175 to 200°C where the intramolecular hydrogen bonded structure is lost. This structure cannot be recovered upon cooling or annealing due to restrictions on conformational rotations that are coupled to a new pattern of intermolecular hydrogen bonding. However, the structure is reformed by dissolving the resin in solution and casting new films. |
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Keywords: | Hydrogen bonding phenolic resins p-cresol/formaldehyde calixarene |
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