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Laser light‐scattering studies of soluble high performance fluorine‐containing polyimides
Author(s) -
Kwan Simon Chi Man,
Wu Chi,
Li Fuming,
Harris Frank W.,
Cheng Stephen Z. D.
Publication year - 1999
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11447
Subject(s) - trifluoromethyl , analytical chemistry (journal) , diamine , radius of gyration , materials science , tetrahydrofuran , scattering , hydrodynamic radius , molar mass , diffusion , radius , chemistry , dynamic light scattering , polymer chemistry , polymer , physics , optics , organic chemistry , nanotechnology , nanoparticle , alkyl , computer security , solvent , computer science , thermodynamics
Two sets of soluble high performance polyimides synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′‐(trifluoromethyl)‐4,4′‐diaminobiphenyl diamine (PFMB), and from 2,2′‐bis(trifluoromethyl)‐4,4′,5,5′‐biphenyl‐tetracarboxylic dianhydride (HFBPDA) and 2,2′‐(trifluoromethyl)‐4,4′‐diaminobiphenyl diamine (PFMB) have been investigated by static and dynamic laser light scattering (LLS) in tetrahydrofuran (THF) at 30°C. The calibrations, for 6FDA‐PFMB: < R g > (nm) = 3.87 × 10 −2 < M w > 0.568 , < R h > (nm) = 2.38 × 10 −2 < M w > 0.560 and < D > (cm 2 /s) = 2.13 × 10 −4 < M w > −0.560 ; for HFBPDA‐PFMB: < R g > (nm) = 2.24 × 10 −2 < M w > 0.626 , < R h > (nm) = 1.27 × 10 −2 < M w > 0.621 and < D > (cm 2 /s) = 3.99 × 10 −4 < M w > −0.621 , have been established, where < M 2 >, < R g >, < R h > and < D > are the weight‐average molar mass, the root mean square z ‐average radius of gyration, the z ‐average hydrodynamic radius and the z ‐average translational diffusion coefficient, respectively. A combination of < M w > and the translational diffusion coefficient distribution G ( D ) leads to the calibrations of D (cm 2 /s) = 2.41 × 10 −4 M −0.564 and D (cm 2 /s) = 6.16 × 10 −4 M −0.656 for 6FDA‐PFMB and HFBPDA‐PFMB, respectively, where D and M correspond to monodisperse species. With these calibrations, we can convert a translational diffusion coefficient distribution G ( D ) into a corresponding molar mass distribution f w ( M ). On the basis of the Kratky‐Porod wormlike chain model, the persistence lengths ( q ) were found to be ˜ 3.3 nm and ˜ 4.5 nm, respectively, for 6FDA‐PFMB and HFBPDA‐PFMB, which indicates that both polyimide chains have an extended conformation. In addition, < R g > / < R h > ˜ (1.7‐1.9) shows that they are in coil conformation. Therefore, we conclude that both polyimides have an extended coil conformation.