Synthesis of Cis-Cisoid or Cis-Transoid Poly(Phenyl-Acetylene)s Having One or Two Carbamate Groups as Oxygen Permeation Membrane Materials.

Yu Zang,Masahiro Teraguchi,Takashi Kaneko,Hongge Jia,Fengjuan Miao,Toshiki Aoki,Yinghui Lun,Xunhai Zhang

doi:10.3390/membranes10090199

Yu Zang, Masahiro Teraguchi + Show 6 more

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https://doi.org/10.3390/membranes10090199

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Abstract

Three new phenylacetylene monomers having one or two carbamate groups were synthesized and polymerized by using (Rh(norbornadiene)Cl)2 as an initiator. The resulting polymers had very high average molecular weights (Mw) of 1.4–4.8 × 106, with different solubility and membrane-forming abilities. The polymer having two carbamate groups and no hydroxy groups in the monomer unit showed the best solubility and membrane-forming ability among the three polymers. In addition, the oxygen permeability coefficient of the membrane was more than 135 times higher than that of a polymer having no carbamate groups and two hydroxy groups in the monomer unit with maintaining similar oxygen permselectivity. A better performance in membrane-forming ability and oxygen permeability may be caused by a more extended and flexible cis-transoid conformation and lower polarity. On the other hand, the other two new polymers having one carbamate group and two hydroxy groups in the monomer unit showed lower performances in membrane-forming abilities and oxygen permeabilities. It may be caused by a very tight cis-cisoid conformation, which was maintained by intramolecular hydrogen bonds.

Highlights

The polarity of the monomers showed a significant impact on the polymerization results, such as yields, solubility, membrane-forming ability, and so on (Tables 1 and 2)
The oxygen permeability coefficient (PO2 ) of the membrane of poly(3) was 420 barrer, which was more than 135 times higher than that of poly(4) having no carbamate group and hydroxy groups with maintaining a similar oxygen permselectivity (PO2 /PN2 )
The other two polymers having one carbamate group and two hydroxy groups in the monomer unit (poly(1) and poly(2)) showed less performance in membrane-forming abilities and oxygen permeabilities. It may be caused by a very tight cis-cisoid conformation that was maintained by intramolecular hydrogen bonds and a higher polarity

Summary

Introduction

Introduction πConjugated polymers like polyacetylenes [1,2,3] have aroused interest because of their noteworthy physical properties, such as conductivity, organomagnetism, and optical nonlinear susceptibility.Among them, poly(substituted acetylene)s such as poly(substituted phenylacetylene)s are useful because of their stability in the air, possibility of a variety of derived structures, and good performances as separation membrane materials [4,5,6,7,8,9,10,11,12]. Poly(substituted phenylacetylene)s are generally rigid polymers and show good oxygen permselectivities. They are soluble and suitable as oxygen permeation membrane materials. The poly(substituted acetylene with two hydroxyl groups)s we reported take cis-cisoid conformation [13,14,15]. As a result, they are expected to have a more rigid backbone than cis-transoid poly(substituted acetylene)s. Cis-cisoid poly(substituted acetylene)s are very promising as better oxygen permeation membrane materials if their processability is good. To discuss this factor—that is, the rigidity of the backbone—we compared the two acetylene polymers having these different conformations

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Conclusion