Effects of physical association through nitrile groups on the MWD-dependent viscosity behavior of polyacrylonitrile solutions

The dipole-dipole interactions between polar nitrile groups of polyacrylonitrile (PAN) affected the molecular weight distribution (MWD)-dependent viscosity behavior of the solutions in N,N -dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). In both solvents, the 16 wt% PAN solutions of broader...

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Bibliographic Details
Published in:Macromolecular research 2017, 25(3), , pp.262-269
Main Authors: Eom, Youngho, Kim, Chaejin, Kim, Byoung Chul
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Complex Fluids and Microfluidics
Dimethyl sulfoxide
Dimethylformamide
Dipole interactions
Interdiffusion
Molecular chains
Molecular weight
Molecular weight distribution
Nanochemistry
Nanotechnology
Physical Chemistry
Polyacrylonitrile
Polymer Sciences
Relaxation time
Shear thinning (liquids)
Soft and Granular Matter
Viscosity
고분자공학
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Summary:The dipole-dipole interactions between polar nitrile groups of polyacrylonitrile (PAN) affected the molecular weight distribution (MWD)-dependent viscosity behavior of the solutions in N,N -dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). In both solvents, the 16 wt% PAN solutions of broader MWD but same weight average molecular weight (MW w ) of 150,000 showed more prominent shear-thinning behavior, agreeing qualitatively with the theoretical prediction by Middleman. The dependence of the thinning behavior on the MWD was more pronounced with DMSO. The decrease of the power-law index by broadening of the MWD was more noticeable in DMSO than in DMF. The UV/vis and FTIR spectra confirmed that DMF produced stronger intra- and intermolecular dipole-dipole pairs between nitrile groups of PAN than DMSO. This indicated that physical association between polymer molecules limited the internal plasticizing effect of the low MW w molecules by disturbing the chain interdiffusion and shear-induced disentanglement. Over the whole range of frequency measured, the higher content of the higher MW w molecules in the broader MWD solutions resulted in the increase of dynamic viscosity and relaxation time but decrease of loss tangent.
ISSN:1598-5032
2092-7673
DOI:10.1007/s13233-017-5034-8