writer：XiaofanHu Won Hee Lee Jiayi Zhao Joon Yong Baea Ju Sung Kim Zhen Wang JinglingYan YongbingZhuang You
keywords：Tr?ger''''''''s Base (TB)-containing polyimide
source：期刊
specific source：Journal of Membrane Science
Issue time：2020年

Ultramicroporous polyimides obtained from bio-based anhydrides were

synthesized for gas separation. Two novel dianhydrides,

5,5''''''''-(mesitylmethylene)bis(4-methylphthalic anhydride) (MMDA) and

5,5''''''''-(9H-fluorene-9,9-diyl)bis(4-methylphthalic anhydride) (FDDA), were

successfully synthesized from guaiacol, a lignin-based bio-material. Due

to the fixed center of o-methyltriphenylmethane and o-methyldiphenylfluorene

units, the bio-based dianhydrides had high energy barriers to rotation,

resulting in highly rigid polymer chains. After polymerization with a

Tr?ger''''''''s Base (TB)-containing diamine using a one-step imidization, two

kinds of bio-based polyimides incorporating TB units (Bio-TBPI-1 and

Bio-TBPI-2) were prepared with reasonable molecular weights and

outstanding thermal properties. Bio-TBPIs demonstrated a microporous

structure determined by high BET surface areas of ～500?m3?g?1, high fractional free volumes (FFVs) of ～0.2, and d-spacings

of ～0.7. In addition, Bio-TBPIs exhibited narrow cavity size

distributions around 0.5?nm, and molecular sieving characteristics due

to the ultramicroporosity. Bio-TBPI membranes displayed excellent gas

separation performance, which was located near the upper bounds of

important gas pairs such as H2/CH4, H2/N2, O2/N2, and CO2/CH4.

The gas separation performance of Bio-TBPIs was better than that of

corresponding TB-based polyimides containing commercial dianhydrides.

The effect of physical aging on gas transport behaviors of Bio-TBPIs was

monitored for 200 days, resulting in loss of permeability and enhanced

selectivities.