(193ah) Highly Polar Polymers Based on Poly(1,3-dioxolane) for Membrane CO2/N2 Separation

Highly
Polar Polymers based on Poly(1,3-dioxolane) for Membrane CO₂/N₂
Separation

Junyi
Liu¹, Ho Bum Park², Haiqing Lin¹

¹Department of
Chemical and Biological Engineering, University at Buffalo, The State
University of New York, Buffalo, NY, USA

²WCU Department of
Energy Engineering, Hanyang University, Seoul, South Korea

Email
address: junyiliu@buffalo.edu, badtzhb@hanyang.ac.kr, haiqingl@buffalo.edu

Prepared for 08A07
Diffusion in Polymers 

Membrane materials
with high CO₂ permeability and high CO₂/N₂
selectivity are in pursuit for CO₂ capture from flue gas derived
from fossil fuel-power plants. The leading materials usually contain
poly(ethylene oxide) (PEO) because the ether oxygens in PEO interact favorably
with CO₂,
resulting in
high CO₂ sorption and permeability, and thus high CO₂/N₂
selectivity.
In this study,
we demonstrate that polymers with higher ether oxygen content than PEO exhibit
better CO₂/N₂ separation performance. Specifically, a
family of polymers containing poly(1,3-dioxlane) (with an O:C ratio of 1:1.5,
compared with 1:2 in PEO) were synthesized by photopolymerization of two
macromonomers,
poly(1,3-dioxolane)
acrylate (PDXLA) and poly(1,3-dioxolane) ethyl ether acrylate (PDXLEA). Both
macromonomers at different chain lengths were prepared via cationic ring
opening polymerization of 1,3-dioxolane. The macromomoners and polymers are
systematically characterized for chemical structures and physical properties using
NMR, DSC,
FTIR,
XRD, etc. Pure-gas solubility and pure‑ and mixed-gas permeability were
determined as a function of pressures and temperatures. These highly polar
polymers
exhibit CO₂/N₂
separation properties above the upper bound in the Robeson’s plot, and better
than PEO based materials. For example, a copolymer prepared from PDXLA and PDXLEA
at a weight ratio of 1:3 (i.e., PDXLEA75) exhibits a mixed-gas CO₂
permeability of 1300 Barrers and CO₂/N₂ selectivity of 62
under humidified environment at 70 ^oC. The structure/property
relationship in this series of copolymers will be elucidated, and their
potential for membrane materials for industrial CO₂ capture from
flue gas will be discussed.