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Domain structure and dynamic heterogeneities of a polyethylene acid ionomer by two‐dimensional solid‐state NMR
Author(s) -
Chin Y.H.,
Kaplan S.
Publication year - 1994
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260321312
Subject(s) - crystallinity , amorphous solid , chemistry , ionomer , solid state nuclear magnetic resonance , polyethylene , diffusion , methacrylic acid , crystallography , polymer chemistry , nuclear magnetic resonance , polymer , copolymer , organic chemistry , thermodynamics , physics
Abstract Two‐dimensional wideline separation (WISE) NMR spectroscopy was employed to investigate the microscopic domain structure of an ethylene‐containing acid ionomer, poly(ethylene‐co‐methacrylic acid). Crystallinities were determined from deconvolution of the proton dimension lineshapes, and domain sizes were computed from proton spin diffusion behavior. The time‐scale for spin diffusion between the acid groups and the amorphous regions is less than 1 ms, because the methacrylic acid groups are situated in the amorphous domains. On the other hand, communication between amorphous and crystalline domains requires several milliseconds, consistent with crystalline domain sizes of ca 4 nm. The presence of intermolecular hydrogen‐bonded cross‐linking is clearly detected by the broad proton linewidth associated with the rigid methacrylic acid groups. It is shown that imbibed hexadecane, which strongly plasticizes the amorphous regions of the copolymer, has little effect on crystallinity, crystalline domain sizes or cross‐link sites.