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Determination of the structural configuration of cresol–novolak resins by 13 C NMR spectroscopy
Author(s) -
Carothers J. A.,
Gipstein E.,
Fleming W. W.,
Tompkins T.
Publication year - 1982
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1982.070270921
Subject(s) - methylene , oligomer , chemical shift , spectroscopy , nuclear magnetic resonance spectroscopy , chemistry , materials science , polymer chemistry , crystallography , stereochemistry , organic chemistry , physics , quantum mechanics
13 C NMR spectroscopy was used to investigate the structures of a series of pure isomeric cresylic novolak resins. Chemical shifts were measured and assigned, and end groups were distinguished from the central repeat units of the chains. Based on these measurements, the number average molecular weight of the para‐cresylic oligomer was determined. A comparison of the 13 C decoupled and coupled spectra of the three isomeric resins indicates that the para isomer has a linear, ordered structure in which the aromatic rings are linked only by ortho–ortho′ methylene‐bridging groups. The structures of the ortho and meta isomers are more complex and contain ortho–ortho′, ortho–para′, and para–para′ methylene bridges.