2020-Effects of sulfonate incorporation and structural isomerism on physical and gas transport properties of soluble sulfonated polyimides
writer：Dajie Zhang, Jong Geun Seong, Won Hee Lee, Shinji Ando, Yinhua Wan, Young Moo Lee*, Yongbing Zhuang*
keywords：Polyimides Sulfonation Gas separation
source：期刊
specific source：Polymer, 191 (2020) 122263
Issue time：2020年
This study presents the effects of sulfonate incorporation and
structural isomerism of soluble sulfonated polyimides (SPIs) for
potential membrane applications. The fluorinated dianhydride (6FDA) and
three commercially sulfonated diamines,
2,4,6-trimethyl-3,5-diaminobenzenesulfonic acid (tDSA), 2,5-diaminobenzenesulfonic acid (pDSA), and 2,4-diaminobenzenesulfonic acid (mDSA),
were used to synthesize SPIs in a one-step polycondensation. The SPIs
are soluble in common organic solvents and have good mechanical
properties as represented by tensile strength of 88.4–115.8 MPa and
elongation at break of 10.3–15.2%. The resulting SPI membranes exhibit
low dielectric constants (~2.61) and linear thermal expansion
coefficients (CTE) ranging from 54.6 to 71.7 ppm/K. These SPI membranes
have fractional free volume (FFV) of 0.119–0.148. The sulfonation incorporation induced closer inter-chain packing, smaller FFV, larger CTE, higher average refractive indices (nav), better transparency and higher ideal selectivities for almost all gas pairs for their membranes. The para-linked TEA-pSPI membrane exhibited a larger inter-chain d-spacing, larger FFV, larger CTE, smaller nav and slightly higher permeability coefficients than the corresponding meta-linked TEA-mSPI
membrane. This study guides molecular architecture for improving
particular membrane performance by introducing sulfonation groups as
well as adjusting either para- or meta-linkages into polymeric main chains.
https://www.sciencedirect.com/science/article/abs/pii/S0032386120301038