Synthesis and oxygen permeation of novel well-defined homopoly(phenylacetylene)s with different sizes and shapes of oligosiloxanyl side groups
Graphical abstract
Introduction
Many gas permselective membranes have been reported on the past three decades [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12] as energy saving separation process. Some of them have been applied for practical use to solve environmental and energy problems. Among them, membranes which oxygen permeates selectively than nitrogen through are very important and interesting in view of scientific and industrial aspects because oxygen and nitrogen have similar sizes and properties, and oxygen enrichment is important for medical and industrial needs [13].
There are three requirements for oxygen permselective membrane materials. First, a polymer can be fabricated to a self-standing membrane and its mechanical strength is high. Second, the membrane shows high oxygen permeability coefficient (: barrer), and third, the membrane shows high oxygen permselectivity . In general, while polymer membranes from rigid macromolecules tend to show brittle nature, high and low , polymer membranes from flexible macromolecules tend to show waxy nature, low and high . Trade-off relationships between and have been often observed in many papers[14], [15], [16].
Syntheses of many poly(substituted acetylene)s and their application to oxygen permselective membrane materials have been reported by Masuda et al. [17], [18], [19], [20], [21], [22], [23]. Because in general poly(substituted acetylene)s have good membrane forming abilities and relatively high , they are very suitable as oxygen permselective membrane materials [17], [18], [19], [20], [21], [22], [23]. On the other hand, it is well-known that polydimethylsiloxane (PDMS) shows many unique characters such as very high gas permeability [24], a low glass transition temperature, and high solubility in ordinary solvents. However, since pure linear PDMS has no self-membrane forming ability, to apply it for separation membranes some chemical modification is needed. The use of short oligosiloxane (ODMS) chains such as disiloxanyl and trisiloxanyl groups was an effective method to use advantages of PDMS as new polymer membrane materials [25], [26], [27], [28], [29], [30], [31], [32], [33].
Therefore, in this study we selected the combination of poly(substituted acetylene)s and PDMS (or ODMS) to obtain good oxygen permselective membrane materials, and designed, synthesized and polymerized new substituted acetylenes with a short ODMS, i.e., an oligosiloxane. Although we reported synthesis and oxygen permeabilities of some poly(substituted phenylacetylene)s having trimethylsilyl groups [34] and fluorine containing groups [35] and cis-cisoidal poly(phenylacetylenes) [36], no oxygen permeation of poly(substituted acetylenes) having ODMS groups have been studied and systematic study was not enough to investigate relationships between chemical structures of polymers and membrane performances from these polymers. Therefore, in this study, we synthesized novel six ODMS-containing phenylacetylenes and polymerized them to obtain the corresponding comb-shped homopolymers with high molecular weights and good solubility. And we fabricated the comb-shaped homopolymers to self-standing membranes and measured their oxygen permselectivity. We discuss relationships between their chemical structures and oxygen permeabilities.
Section snippets
Materials
All the solvents used for monomer synthesis and polymerization were distilled as usual. 1,4-dibromobenzene used as starting materials, was purchased from Aldrich Chemical Co., Inc. The polymerization initiators, [Rh(nbd)Cl]2 (nbd = 2,5-norbornadiene), and tungsten(VI) chloride (WCl6) purchased from Aldrich Chemical Co., Inc., were used as received.
Measurement of oxygen and nitrogen permeability
Oxygen and nitrogen permeability coefficients ( and : cm3(STP) ·cm·cm−2·s−1·cmHg−1) and the oxygen separation factor (α = ) were
Syntheses of seven new phenylacetylene monomers having different lengths and shapes of short oligodimethylsiloxanyl (ODMS) groups (Chart 1)
As shown in Chart 1 nos.7–13, seven new phenylacetylene monomers having different lengths and shapes of a short oligodimethylsiloxanyl (ODMS) group were designed and synthesized. At the same time, some phenylacetylenes having trimethylsily groups at different positions (nos.4–6) and having no silicon atoms (nos.1–3) have been synthesized as a reference. All the monomers were purified by vacuum distillation.
Conclusions
We synthesized six new phenylacetylenes having short oligodimethylsiloxane (ODMS) substituents with different sizes and shapes. Homopolymerization of the silicon-containing monomers yielded the corresponding homopoly(substituted phenylacetylene)s with high molecular weights and good solubility. The comb-shaped polymers were able to be fabricated by solvent casting method to self-standing membranes which had strength enough to resist one atom pressure difference in permeation measurements, even
Acknowledgments
This work was supported by the National Natural Science Foundation of China [21404064]; the Natural Science Foundation of Heilongjiang Province of China [LC2016022]; the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province [UNPYSCT-2016089]; Scientific Research Foundation for the Returned Overseas Chinese Scholars, Human Resources and Social Security Department of Heilongjiang province of China [[2017] No.490]; the JSPS KAKENHI Grant Number [16H04153];
References (39)
- et al.
Reverse-selective polymeric membranes for gas separations
Prog. Polym. Sci.
(2013) - et al.
Current challenges in membrane separation of CO2 from natural gas: a review
Int. J. Greenh. Gas Control
(2013) - et al.
Energy-efficient polymeric gas separation membranes for a sustainable future: a review
Polymer
(2013) - et al.
Advanced polyimide materials: syntheses, physical properties and applications
Prog. Polym. Sci.
(2012) - et al.
Pure- and mixed-gas permeation properties of a microporous spirobisindane-based ladder polymer (PIM-1)
J. Membr. Sci.
(2009) Macromolecular design of permselective membranes
Prog. Polym. Sci.
(1999)Correlation of separation factor versus permeability for polymeric membranes
J. Membr. Sci.
(1991)The upper bound revisited
J. Membr. Sci.
(2008)- et al.
Poly[1-(trimethylsilyl)-1-propyne] and related polymers: synthesis, properties and functions
Prog. Polym. Sci.
(2001) - et al.
Novel poly(diphenylacetylene)s with both alkyl and silyl groups as gas permeable membranes: synthesis, desilylation, and gas permeability
Polymer
(2010)
A series of poly(diphenylacetylene)s bearing sulfonic acids: synthesis, characterization, and gas permeability
Polymer
Macromolecular design of permselective membranes
Prog. Polym. Sci.
New copolyimide membranes with high siloxane content designed to remove polar organics from water by pervaporation
J. Membr. Sci.
Syntheses of siloxane-grafted aromatic polymers and the application to pervaporation membrane
React. Funct. Polym.
Synthesis and oxygen permeation of novel polymers of phenylacetylenes having two hydroxyl groups via different lengths of spacers
Polymer
Polymeric gas separation membranes
Macromolecules
Gas separation usingpolymer membranes: an overview
Polym. Adv. Technol.
Separation of gases using solubility-selective polymers
Trends Polym. Sci.
Polymers of intrinsic microporosity
ISRN Mater. Sci.
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