TY - JOUR
T1 - Acetate-functional thermally rearranged polyimides based on 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane and various dianhydrides for gas separations
AU - Liu, Wenfang
AU - Xie, Wei
PY - 2014/1/15
Y1 - 2014/1/15
N2 - Three acetate-functional polyimides based on 2,2-bis(3-amino-4-hydroxy- phenyl)hexafluoropropane (APAF) and dianhydrides with different linking groups (-O-, -CO-, and -C(CF3)2-) were prepared, from which films were prepared and thermally rearranged (TR) to form poly(benzoxazole) dense membranes. The polymers were characterized by 1H nuclear magnetic resonance, Fourier transform infrared, differential scanning calrimetry, thermogravimetric analysis-mass spectrometry, and wide-angle X-ray diffraction. Transport properties of the TR membranes were investigated, and effects of the linking group and TR conversion rate on the membrane performance were discussed. Among the TR polymers studied, those bearing larger linking groups have higher d-spacing, fractional free volume, and gas permeability. The membrane permeability to gases increases with TR conversion rate and follows the order H2 > CO2 > O2 > N2 > CH4, except that CO2 surpasses H2 in APAF-6FDA-TR450. The CO2/CH4 separation performance of all of the TR polymers studied surpasses Robeson's 1991 upper bound (J. Membr. Sci. 1991, 62 (2), 165-185), and APAF-6FDA-TR450 is most favorable, the performance of which is closest to the 2008 upper bound (J. Membr. Sci. 2008, 320 (1-2), 390-400).
AB - Three acetate-functional polyimides based on 2,2-bis(3-amino-4-hydroxy- phenyl)hexafluoropropane (APAF) and dianhydrides with different linking groups (-O-, -CO-, and -C(CF3)2-) were prepared, from which films were prepared and thermally rearranged (TR) to form poly(benzoxazole) dense membranes. The polymers were characterized by 1H nuclear magnetic resonance, Fourier transform infrared, differential scanning calrimetry, thermogravimetric analysis-mass spectrometry, and wide-angle X-ray diffraction. Transport properties of the TR membranes were investigated, and effects of the linking group and TR conversion rate on the membrane performance were discussed. Among the TR polymers studied, those bearing larger linking groups have higher d-spacing, fractional free volume, and gas permeability. The membrane permeability to gases increases with TR conversion rate and follows the order H2 > CO2 > O2 > N2 > CH4, except that CO2 surpasses H2 in APAF-6FDA-TR450. The CO2/CH4 separation performance of all of the TR polymers studied surpasses Robeson's 1991 upper bound (J. Membr. Sci. 1991, 62 (2), 165-185), and APAF-6FDA-TR450 is most favorable, the performance of which is closest to the 2008 upper bound (J. Membr. Sci. 2008, 320 (1-2), 390-400).
UR - http://www.scopus.com/inward/record.url?scp=84892693288&partnerID=8YFLogxK
U2 - 10.1021/ie403421u
DO - 10.1021/ie403421u
M3 - Article
AN - SCOPUS:84892693288
SN - 0888-5885
VL - 53
SP - 871
EP - 879
JO - Industrial and Engineering Chemistry Research
JF - Industrial and Engineering Chemistry Research
IS - 2
ER -