This work reports the synthesis and hydrogenation of polynorbornenes with functionalized imide
side groups, specifically, poly(N-phenyl-exo,endo-norbornene-5,6-dicarboximide), as well as the sulfonation of
the hydrogenated polymer. The gas transport characteristics and permselectivity of membranes prepared from
the three separated polymers were thoroughly investigated. The results show that hydrogenation of the starting
polymer promotes packaging efficiency, which is even enhanced by further sulfonation of the hydrogenated chains.
The economy of free volume is reflected in the permeation and permselectivity coefficients of membranes prepared
from the polymers. The study of electromotive forces of concentration cells with the sulfonated membrane separating
hydrochloric solutions of different concentration suggests that the membranes exhibit high permselectivity to
protons that decreases as concentration increases. However, a sharp increase in the electromotive force occurs at
high concentrations. The fact that this increase is not observed in the electromotive forces of concentration cells
with sodium chloride in the compartment cells suggests the formation of pair ions between protonated imide
groups and chloride ions at high concentration that restrains co-ions mobility in the membrane. The membranes
exhibit pretty good permselectivity to protons and sodium ions which makes them useful for ionic separation
applications, such as electrodialysis. However, owing to the low water uptake, the protonic conductivity of the
membranes equilibrated with water is nearly 2 orders of magnitude below that reported for Nafion membranes.
The synthesis of (N-3,5-bis(trifluoromethyl)phenyl-exo-endo-norbornene-5,6-dicarboximide) as well as the ring opening methatesis polymerization (ROMP) of this monomer to yield poly(N-3,5-bis-(trifluoromethyl)phenyl-exo-endo-norbornene-5,6-dicarboximide) are reported. The glass transition of the polymer is 162°C. Solubility coefficients of different gases (nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethane, ethylene, propane, and propylene) in membranes prepared by casting from poly(N-3,5-bis(trifluoromethyl)phenyl-exo-endo-norbornene-5,6-dicarboximide) solutions were measured at several temperatures and pressures. The interpretation of the sorption results by the dual-mode model gives the Henry and Langmuir contributions to the solubility. As usual in glassy membranes, sorption processes are exothermic and the activation energies associated with the Henry and Langmuir parameters are also negative. Gas sorption in the continuous amorphous phase was interpreted in terms of the FloryHuggins theory obtaining reasonable values for the enthalpic parameter that accounts for the gas (in liquid form)-polymer interactions. The use of this approach to simulate gas sorption in polymers is discussed.
This work reports the synthesis of exo-N-phenyl-7-oxanorbornene-5,6-dicarboximide and its ring-opening metathesis copolymerization with norbornene to yield poly(exo-N-phenyl-7-oxanorbornene-5,6-dicarboximide-co-norbornene), with molar ratio 50/50. The glass transition temperature of the copolymer is 125°C. Permeation and sorption processes of different gases (hydrogen, nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethylene, and ethane) were measured in membranes prepared by casting from solutions of the copolymer in chloroform. The Langmuir capacity of the gases is relatively small due to the nearness of the glass transition temperature of the polymer to the working temperature. The solution of the most condensable gases in the continuous phase of the membrane is apparently described by the Flory-Huggins theory of polymer-diluent mixtures. In general, the membranes exhibit a reasonably high separation coefficient of hydrogen with respect to ethane, ethylene, nitrogen, and methane. The value of R(O 2/N2) at room temperature lies in the vicinity of 5.
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