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Final Draft of the original manuscript: Fritsch, D.; Bengtson, G.; Carta, M.; McKeown, N.B.: Synthesis and Gas Permeation Properties of Spirobischromane-Based Polymers of Intrinsic Microporosity In: Macromolecular Chemistry and Physics ( 2011) Wiley DOI: 10.1002/macp.201100089

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Synthesis and Gas Permeation Properties of Spirobischromane-Based Polymers of Intrinsic Microporositya. Detlev Fritsch*, Gisela Bengtson, Mariolino Carta, Neil B. McKeown ––––––––– D. Fritsch, G. Bengtson Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, 21502 Geesthacht, Germany E-mail: detlev.fritsch@hzg.de M. Carta, N.B. McKeown School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK. –––––––––

Polymers of intrinsic microporosity (PIMs) possess molecular structures composed of fused

rings with linear units linked together by a site of contortion so that the macromolecular

structure is both rigid and highly non-linear. For PIM-1, which has previously demonstrated

encouraging gas permeability data, the site of contortion is provided by the monomer 5,5',6,6'-

tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane. Here we describe the synthesis and

properties of a PIM derived from the structurally related 6,6’,7,7’-tetrahydroxy-4,4,4’,4’-

tetramethyl-2,2’-spirobischromane and copolymers prepared from combination of this

monomer with other PIM-forming biscatechol monomers, including the highly rigid monomer

9,10-dimethyl-9,10-ethano-9,10-dihydro-2,3,6,7-tetrahydroxyanthracene. Generally the

polymers display good solubility in organic solvents and have high average molecular masses

(Mw) in the range 80000-200000 g/mol and, therefore, are able to form robust, solvent-cast

films. Gas permeability and selectivity for He, H2, N2, O2, CO2 and CH4 were measured for

the polymers and compared to the values previously obtained for PIM-1. The

spirobischromane-based polymers demonstrate enhanced selectivity for a number of gas pairs

_____________________________

a Supporting Information is available at Wiley Online Library.

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but with significantly lower values for permeability. The solubility coefficient for CO2 of two

of the co-polymers exceed even that of PIM-1, which previously demonstrated the highest

value for a membrane-forming polymer. Therefore, these polymers might be useful for gas or

vapor separations relying on solubility selectivity.

Introduction

The preparation of new polymers for use as the selective layer in membranes for gas

separations continues to be an important area of research. Target applications include

hydrogen recovery, nitrogen generation and carbon dioxide capture.[1-5] To date, the basic gas

permeability data of a vast number of polymers has been measured and the interpretation of

the data from such studies suggests a trade-off relationship between the desirable properties of

high permeability (P) and good selectivity (xy = Px/Py) for a given gas pair (x and y).

Robeson identified an upper-bound in plots of log Px versus log xy and the position of a

polymer’s permeability data on the plot is a useful performance indicator.[6] Unfortunately,

despite the impressive development of new polymers over the past two decades, as

demonstrated by the recent re-positioning of Robeson’s upper bound for all important gas

pairs, the various classes of ‘ultrapermeable’ polymers still possess insufficient selectivity for

most gas separations and the goal of enhancing their selectivity remains very challenging.[7-8]

Theory suggests that this enhancement could be achieved in two ways, either by improving

the solubility selectivity of the material or by increasing the stiffness of the polymer chain

whilst simultaneously increasing inter-chain spacing, however, the latter should not be

increased so much that mobility selectivity is lost.[9]

Recently, a novel class of ultrapermeable polymer based on polybenzodioxanes, called

Polymers of Intrinsic Microporosity (PIMs), has been studied with the archetype, PIM-1,

demonstrating encouraging properties for gas and vapor separations, with permeability data

on or above Robeson’s updated upper bound for a number of important gas pairs (e.g. O2/N2,

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CO2/CH4).[10, 11-17] The excellent properties of PIM-1 appear related to both its intrinsic

microporosity, with a high concentration of subnanometre micropores, and the remarkably

high solubility coefficients for all gases relative to other ultrapermeable polymers.[10] PIM-1

is prepared by the reaction between commercially available 5,5’,6,6’-tetrahydroxy-3,3,3,3-

tetramethyl-1,1-spirobisindane 1 and 2,3,5,6-tetrafluoroterephthalonitrile 2.[11] In this paper,

we describe the synthesis and basic gas permeation properties of a related polybenzodioxane

derived from the spirocyclic monomer 6,6’,7,7’-tetrahydroxy-4,4,4’,4’-tetramethyl-2,2’-

spirobischromane (CO15). This molecule was first reported by Baker in 1939 and has since

found application as an antioxidant for isotactic polypropylene and within photographic and

photoresist materials.[18-21] The clear structural similarity of CO15 to the spirobisindane

monomer 1 suggested that polybenzodioxanes derived from it should demonstrate intrinsic

microporosity.[22] It was hoped that its additional two oxygen atoms may further enhance the

solubility coefficient of gases and vapors within the resulting PIMs caused by increasing

polarity compared to spirobisindane. Similarly, monomers that represent simple structural

modifications of the original spirocyclic monomer 1, with additional methyl or bromine

substituents placed around the spirobisindane core,[23] or the highly rigid 9,10-dimethyl-9,10-

ethano-9,10-dihydro-2,3,6,7-tetrahydroxyanthracene (CO1),[24] were used in conjunction with

CO15 for making copolymers. It was hoped that these substituents might further frustrate

packing of the polymer in the solid state and thus enhance the intrinsic microporosity of the

resulting PIMs.

Experimental Section

Materials

Most chemicals were obtained from Sigma-Aldrich and were used without further treatment.

The exceptions were 2,3,5,6-tetrafluoroterephthalonitrile (2), which was generously donated

by Lanxess and sublimated twice at 70 °C/10-3 mbar before use, 5,5',6,6'-tetrahydroxy-

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3,3,3',3'-tetramethyl-1,1'-spirobisindane (1) and 6,6’,7,7’-tetrahydroxy-4,4,4’,4’-tetramethyl-

2,2’-spirobischromane (CO15) were obtained from ABCR, Germany. Co-monomers CO1,

CO2, CO6 and CO19 were prepared in our laboratory following the procedures described

below. K2CO3 (Merck) was dried under vacuum at 110 °C for 12 h and milled in a vibratory

mill for 10 min.

Characterization and Methods

Gel permeation chromatography: For GPC, a column combination (precolumn-SDV-linear,

SDV-linear and SDV-102 nm with inner diameter = 4.6 mm and length = 53 cm, Polymer

Standards Service GmbH, Germany (PSS)) was used at 1.0 ml/min running CHCl3 as eluent

at 30 °C. About 0.4 wt.-% solutions were injected by a 40 µl injector to the columns. A

combination of refractive and viscosity detectors was used with chlorobenzene acting as

internal standard. For data evaluation, the universal calibration mode of the WINGPC

software from PSS, Germany, was selected, based on calibration using polystyrene standards.

Inherent viscosity: Measurements were made with an Ubbelohde capillary (Nr. 501 10/1

(Schott, Germany), maintained at 20 °C using a mixed solvent of CHCl3/trifluoroacetic acid

(4/1, v/v) and 20 mg cm-³. NMR spectroscopy: NMR spectra were collected on a Bruker

AV300 NMR spectrometer operating at a field of 7T (300.13 MHz for 1H, 75.48 MHz for

13C) using a 5 mm 1H/13C TXI probe and a sample temperature of 298 K. 1H spectra were

recorded applying a 10 s 90° pulse. 13C spectra were recorded using dept45, deptq135 and

cpd sequences employing a waltz-16 decoupling scheme. The relaxation delay was chosen so

that the sample was fully relaxed. IR spectroscopy (FT-IR): Spectra were collected on a

Bruker Equinox 55 spectrometer in ATR mode. TGA: Data were collected on a TG 209 F1

Iris, (Netzsch, Germany), measured with Argon purge. Surface area measurement: Surface

area was measured using nitrogen adsorption with a Coulter 3100 instrument.

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Membrane preparation and gas measurement

Thick polymer films were obtained by solution casting from an appropriate solution (5-10 %

wt/vol) into an accurately levelled Teflon® circular dish. For a low-boiling solvent such as

CHCl3, the dish was covered by a lid and the system was gently purged using a stream of N2

or Ar. For higher boiling solvents, the dish was placed on a heating plate set to 60 °C and the

solvent was evaporated overnight. Solvent exchange was achieved by methanol treatment

overnight. The treated membranes were dried in high, oil-free vacuum for 16 h at 120 °C and

stored for measurement in a desiccator over silica gel. Gas permeation data were measured at

30 °C with pure gases, using a proprietary developed pressure increase time-lag apparatus

operated at low feed pressure (typically 200–700 mbar), starting with oil free vacuum (<10-4

mbar). Permeability coefficient P, was calculated from the slope in the steady-state region and

apparent diffusion coefficient D, from the time-lag, θ, using D= l2/6θ, where l is the

membrane thickness. Solubility (S) was calculated by equation 1.

PA = SA * DA (1)

Monomer preparation

9,10-Dimethyl-9,10-ethano-9,10-dihydro-2,3,6,7-tetrahydroxy-anthracene (CO1)

According to Niederl and Nagel,[25] powdered pyrocatechol (10.4 g, 94.5 mmol) was added to

ice-cooled sulphuric acid (200 ml, 70%) to give a colorless suspension. 2,5-Hexanedione (5.5

ml, 47 mmol) was added drop-wise to form a green mixture. After 0.5 h of stirring, the ice

bath was removed and the color of the mixture turned to reddish-brown and stirring was

continued for 5 days at room temperature. The precipitate was removed from the acid by

filtration with a glass frit and washed with water. The dark red crude product was

recrystallized twice from ethyl acetate to yield 10.5g (74%) of light grey powder, mp 265 °C.

FT-IR (ATR): 3497, 3295, 2945, 1617, 1445, 1297, 1220, 1139, 992, 879, 813, 802 cm-1. 1H-

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NMR (300 MHz, DMSO-d6, δ): 1.39 (s, 4H), 1.67 (s, 6H), 6.6 (s, 4H), 8.41 (s, 4H) ppm. 13C-

NMR (75 MHz, DMSO-d6, δ): 18.5, 36.2, 108.8, 137.6, 141.7 ppm.

3,3,3´,3´, 4,4´-Hexamethyl-5,6,5´,6´-tetrahydroxy-1,1´-spirobisindane (CO2)[26, 27]

3-Methylcatechol (11.2 g, 90 mmol) was dissolved in acetic acid (22 ml) and hydrobromic

acid (24 ml) was added. Acetone (14 ml, 190 mmol) was added drop–wise and the resulting

dark-brown suspension was heated to 120 °C for 12h. After cooling, the mixture was poured

into water (500 ml). The dark precipitate was collected by filtration and washed several times

with diethyl ether resulting in a fine white powder. Drying in vacuum yielded 7.7g (46%), mp

230 °C. FT-IR (ATR): 3400, 2957, 1566, 1480, 1358, 1309, 1000, 840, 766 cm-1. 1H-NMR

(300 MHz, DMSO-d6, δ): 1.2-1.25 (2s, 12 H, al-CH3), 1.5 (s, 6H, ar-CH3), 2.02-2.06 (m, 4H,

al-CH2), 6.4 (s, 2H, ar-H), 7.7 (s, 2H, OH) 8.8 (s, 2 H, OH) ppm. 13C-NMR (75 MHz, DMSO-

d6, δ): 11.4, 30.3, 32.9, 42.1, 57.5 (spiro-C), 57.8 (CH2), 106.4, 120.1, 137.8, 141.6, 142.7,

144.3 ppm. Anal. calcd for C23H28O4: C 74.97, H 7.66; found: C 75.1, H 8.4.

Dibromo-5,6,5´,6´-tetrahydroxy-3,3,3´,3´-tetramethyl-1,1´-spirobisindane (CO6)

Spirobisindane 1 (4.0 g, 11.8 mmol) was dissolved in 1,4-dioxane (40 ml), resulting in a clear

yellow solution. The solution was cooled to 15 °C and a solution of bromine (1.3 ml, 26 mmol

dissolved in 10 ml chloroform) was added drop-wise over 1h to give a clear orange solution.

The reaction mixture was stirred for 12 h and poured into water (300 ml). The CHCl3 phase

was separated and the water phase extracted 3 times with diethyl ether (20 ml). The combined

organic phase was dried (anhydrous Na2SO4) and evaporated under reduced pressure to give

the crude product (7.0 g) as a brown powder, which contained about 10 to 15 wt% dioxane (as

determined by 1H-NMR, TGA); Mp. 135-140 °C. Complete removal of dioxane was achieved

by chromatography on silica gel with CHCl3/MeOH 8:1 or ethylacetate/cyclohexane 3:1.

Yield: 90-95%. Mp. 110 °C. FT-IR (ATR): 3331, 2957, 2862, 1474, 1434, 1283, 1255, 1147,

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1115, 1080, 867 cm-1. 1H-NMR (300 MHz, DMSO-d6, δ): Isomer 1 (60%) (1 aromatic-H

peak only): 1.40 (s, 6H) 1.49 (s, 6H), 2.08-2.27 (m, 4H), 6.17 (s, 2H), 8-9 (br, 4H, (OH)) ppm.

Isomer 2 (40%): 1.21 (s, 6H), 1.30 (s, 6H), 1.9-2.15 (m, 4H), 6.10 (s, 1H), 6.62 (s, 1H), 8-9

(br, 4H, OH) ppm. 13C-NMR (75 MHz, DMSO-d6, δ): Isomer 1: 28.6 -29.0 (al-CH3), 45.3

(al-C(CH3)), 55.8 (C-spiro), 60.8 (al-CH2), 106.3 (ar-C-Br), 109.2 (ar-C-H), 137.8, 141.4,

141.8, 145.3 (ar-C) ppm. Anal. calcd for C21H22Br2O4: C 50.63, H 4.45, Br 32.08; found: C

50.6, H 4.6, Br 31.9.

3,3´-Diethyl-5,5’,6,6’-tetrahydroxy-3,3’,2-trimethyl -1,1´-spirobisindane (CO19)[26-28]

A slightly modified procedure to that used for the synthesis of CO2 was employed.

Pyrocatechol (9.91 g, 90 mmol) was dissolved in 2-butanone (10.82 g, 150 mmol) and the

solution was added drop-wise to a mixture of acetic acid (22 ml) and hydrobromic acid (24

ml). The resulting pink solution was heated to 120 °C for 4 h, during this time the solution

turned dark-brown and a precipitate was formed. The mixture was poured into water (300 ml)

to form a red precipitate, which was collected by filtration. The wet powder was washed

several times with CHCl3 and dried in vacuum for 24 h at 50 °C, 1 mbar to yield 8.78g (51%)

of an off-white powder, dec. >300°C. FT-IR (ATR): 3462, 3288, 2958, 2876, 1612, 1506,

1450, 1293, 1151, 881, 801, 779 cm-1. 1H-NMR (300 MHz, DMSO-d6, δ): 0.60-0.65 (m, 6H),

0.93 (s, 3H), 1.15-1.20 (s, m 3H), 1.23 (s, 3H), 1.52-1.58 (m, 4 H), 2.07-2.49 (m, 3H), 6.00-

6.05 (m, 2H), 6.18-6.23 (m, 2H), 6.40-6.46 (m, 2H), 8.45-8.50 (m, 4H) ppm.

Polymer preparation

PIM-CO15; Procedure I

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A two-necked round bottom flask was charged with 6,6’,7,7’-tetrahydroxy-4,4,4’,4’-

tetramethyl-2,2’-spirobischromane (CO15) (1.000 g, 2.68 mmol), 2,3,5,6-

tetrafluoroterephthalonitrile (2) (537 mg, 2.68 mmol) and anhydrous dimethylformamide

(DMF; 30 ml) under a dry nitrogen atmosphere. The mixture was heated to 65 °C, until the

two monomers were completely dissolved, then anhydrous potassium carbonate (2.84 g,

20.64 mmol) was added and the mixture stirred for 96 h. The solution was quenched with

water (100 ml), the solid collected by filtration and washed repeatedly with water and

acetone. The solid was dissolved in CHCl3 (20 ml), the solution filtered through cotton wool

and poured into a flask containing a mixture of acetone/methanol (2/1, 150 ml). The product

was collected by filtration and dried under high vacuum overnight to give the final product as

a yellow solid (1.25 g, 95%). IR (evaporated film from CHCl3): 2920, 2239, 1739, 1632,

1322, 1049, 909, 732 cm-1; 1H NMR (400 MHz; CDCl3, δ): 6.97 (br s, 2H), 6.33 (br s, 2H),

2.09 (br s, 2H), 1.97 (br s, 2H), 1.55 (br m, 6H), 1.33 (br s, 6H); 13C NMR (100 MHz; CDCl3,

δ): 147.0, 139.3, 138.7, 137.9, 134.3, 129.1, 114.4, 109.2, 106.1, 98.3, 94.1, 45.6, 32.1, 30.9.

BET surface area = 518 m2/g; total pore volume = 0.3769 cm3/g at (p/po) = 0.98, on

adsorption cycle; TGA analysis (nitrogen): 5% loss of mass occurs at ~ 390 °C full thermal

degradation commences at ~ 480 °C.

PIM-CO15; Procedure II

CO15 (1.120 g, 3.00 mmol) and 2,3,5,6-tetrafluoroterephthalonitrile (2) (0.600g, 3.00 mmol)

were dissolved in dimethylacetamide (DMAC; 10 ml) and added to a 3-neck-flask, equipped

with condenser, an inlet for Ar gas and Dean-Stark trap filled with toluene. K2CO3 (0.912g,

6.60 mmol) and 5 ml toluene were added to form a yellow suspension. Soon after immersion

in a hot oil bath maintained at 160 °C (60 s), the suspension started foaming and the stirrer

stopped due to the increase in viscosity of the reaction mixture. Addition of further toluene (5

ml) allowed stirring to recommence. The suspension was kept without further changes for

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another 0.5 h and then precipitated in methanol (300 ml). The resulting yellow solid was

filtered off, added to boiling water (50 ml) for 0.5 h, collected by filtration and dried in an

oven at 15 h, 70 °C. Re-precipitation was performed from CHCl3 (30 ml)/TFA (1 ml) solution

into MeOH (300 ml). After drying (70 °C/24 h) 1.44 g of polymer was obtained (98% yield).

NMR and IR data are identical to the polymer prepared using Procedure 1.

PIM1-CO15-75 (by Procedure II)

m:n = 3:1

Monomers CO15 (0.835 g, 2.25 mmol), 1 (0.255 g, 0.75 mmol) and 2 (0.600 g, 3.00 mmol)

were polymerized using Procedure II except the reaction time was extended to 1 h. Polymer

PIM1-CO15-75 was obtained as a yellow powder (1.248 g; 86%) which formed flexible,

free-standing films. GPC (CHCl3): Mw = 125000 g mol-1, Mw/Mn = 8.4, Mp = 61000 g mol-1.

1H-NMR (300 MHz, CDCl3, δ): 6.94 (bs, CO15), 6.80 (bs, Spiro), 6.40 (bs, Spiro), 6.30 (bs,

CO15), 2.33 (bm, Spiro), 2.08 (bm, CO15 + Spiro), 1.94 (bm, CO15), 1.53 (bs, CO15),

1.31bs, CO15 + Spiro). FT-IR (ATR): 2958, 2240, 1448, 1314, 1291, 1264, 1157, 1126, 1009,

876 cm-1.

PIM1-CO15-50 (by Procedure II)

m:n = 1:1

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Monomers CO15 (0.559g, 1.50 mmol), 1 (0.511g, 1.50 mmol) and 2 (0.600 g, 3.00 mmol)

were polymerized using Procedure II as described except the reaction time was extended to 1

h. Polymer PIM-1-CO15-50 was obtained as a yellow powder 1.484g (99%) which formed

flexible, free-standing films. GPC (CHCl3): Mw = 195000 g mol-1, Mw/Mn = 1.4, Mp = 153000

g mol-1. 1H-NMR (300 MHz, CDCl3, δ): 6.94 (bs, CO15), 6.80 (bs, Spiro), 6.40 (bs, Spiro),

6.30 (bs, CO15), 2.33 (bm, Spiro), 2.08 (bm, CO15 + Spiro), 1.94 (bm, CO15), 1.53 (bs,

CO15), 1.31bs, CO15 + Spiro). FT-IR (ATR): 2958, 2240, 1448, 1314, 1291, 1264, 1157,

1126, 1009, 876 cm-1. Anal. calcd for C58H40N4O10: C 73.1, H 4.23, N 5.88; found: C 72.7, H

4.5, N 5.3.

PIMCO1-CO15-50: Procedure III

m:n = 1:1

Monomers CO1 (0.448 g, 1.50 mmol), CO15 (0.559 g, 1.50 mmol) and 2 (0.600 g, 3.00

mmol) were dissolved in DMAc (10 ml) to form an orange-red solution. Addition of 0.913g

(6.60 mmol) K2CO3 caused a color change to orange-yellow. The reaction was immersed in

an oil-bath maintained at 150 °C and after 1.5 min the mixture grew so viscous that

diethylbenzene (DEB; 10 ml) was added and stirring continued for a further 0.5 h then poured

into methanol (300 ml). The resulting yellow solid was collected by filtration. The copolymer

is insoluble in CHCl3 and dichlorobenzene and therefore was purified by washing with

acetone to yield a yellow solid (1.311 g, 79%). It dissolved readily in quinoline to form a clear

yellow film. 1H-NMR (300 MHz, CDCl3/TFA, ): 6.93 (bs, CO1+CO15), 6.33 (bs,

CO1+CO15), 2.06 (bm, CO15), 1.87 (bs, CO1), 1.55 (bs, CO15), 1.33 (CO15). FT-IR (ATR):

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2963, 2239, 1445, 1314, 1267, 1158, 1128, 1008, 879 cm-1. Anal. calcd for C55H34N4O10: C

72.52, H 3.76, N 6.15; found: C 71.6, H 3.8, N 6.1.

PIMCO2-CO15-50 (by Procedure II)

m:n = 1:1

Monomers CO2 (0.553 g, 1.50 mmol), CO15 (0.558 g, 1.50 mmol), and 2 (0.600 g, 3.00

mmol) in DMAc (10 ml) were polymerized using Procedure II as described above except that

the reaction time was extended to 1.3 h to yield PIMCO2-CO15-50 (1.415g, 96%). GPC

(CHCl3): Mw = 112000 g mol-1, Mw/Mn = 6.3, Mp = 87000 g mol-1. 1H-NMR (300 MHz,

CDCl3, ): 6.95 (bs, CO15), 6.70 (bs, CO2), 6.31 (bs, CO15), 2.26 (bm, CO2), 2, 08 (bm,

CO15), 1.94 (bm, CO15), 1.73 (bs, CO2), 1.32 (bs, CO2+CO15). FT-IR (ATR): 2958, 2239,

1448, 1325, 1293, 1265, 1158, 1127, 1050, 1004, 904, 876 cm-1. Anal. calcd for:

C60H44N4O10: C 73.46, H 4.52, N 5.71; found: C 72.7, H 4.5, N 5.3.

PIMCO6-CO15-50 (by Procedure III)

m:n=1

Monomers CO6 (1.371 g, 2.68 mmol), CO15 (0.9955 g, 2.67 mmol) and 2 (1.071 g, 5.35

mmol) were polymerized using Procedure III. The resulting copolymer (yield 1.557g, 52%) is

- 13 -

only partially soluble in CHCl3 but dissolves readily in dichlorobenzene also forms a clear

yellow film using this solvent. 1H-NMR (300 MHz, CDCl3/TFA, ): 6.95 (bs, CO15), 6.82

(bs, CO6+CO15), 6.40 (bs, CO6), 6.30 (bs, CO15), 2.35 (bm, CO6), 2.09 (bm, CO15), 1.93

(bm, CO15), 1.54 (bm, CO15), 1.32 (bs, CO6+CO15). FT-IR (ATR): 2960, 2238, 1441, 1314,

1292, 1157, 1126, 1014, 875 cm-1. Anal. calcd for C58H38Br2N4O10: C 62.72, H 3.45, Br

14.39, N 5.04; found: C 62.0, H 3.5, Br 14.6, N 5.1.

PIMCO19-CO15-50 (by Procedure III)

n

mO

O

O

O

O

O

CN

CN

*

*O

O

*

*CN

CN

O

O

m:n = 1:1

Monomers CO19 (0.575 g, 1.50 mmol), CO15 (0.559 g, 1.50 mmol) and 2 (0.600 g, 3.00

mmol) were polymerized using Procedure III. The resulting copolymer (1.402 g; 94%)

dissolves readily in CHCl3. GPC (CHCl3): Mw = 86000 g mol-1, Mw/Mn = 5.5, Mp = 75000 g

mol-1. 1H-NMR (300 MHz, CDCl3, ): 6.95 (bs, CO15), 6.78 (bs, CO19), 6.50+6.43 (bs,

CO19), 6.30 (bs, CO15), 2.45 (bm, CO19), 2.06 (bm, CO15+CO19), 1.93 (bm,

CO15+CO19), 1.54 (bm, CO15+CO19), 1.32 (bm, CO15+CO19), 0.88 (bt, CO19). FT-IR

(ATR): 2962, 2239, 1446, 1262, 1156, 1125, 1007, 875, 754 cm-1.

PIM-CO19

O

O*

*

CN

CN

O*

O *n

- 14 -

CO19 (1.148 g, 3.00 mmol) and 2 (0.600 g, 3.00 mmol) were polymerized by Procedure III

within 1h. The polymer PIM-CO19 was re-precipitated from CHCl3 into MeOH, to yield

1.44 g of a light-yellow powder (95%). It showed good film forming properties from CHCl3

solution. GPC (CHCl3): Mw = 72000 g mol-1, Mw/Mn = 4.7, Mp = 70000 g mol-1. 1H-NMR

(300 MHz, CDCl3, ): 6.79 (bs, 2H), 6.50 (bs, 1H), 6.28 (bs, 1H), 2.45 (bm, 2H), 1.62 (bm,

5H), 1.27 (bm, 6H), 0.88 (bt, 6H). FT-IR (ATR): 2964, 1447, 1264, 1010, 875, 753 cm-1.

Results and Discussion

Monomer synthesis

The spirochromane monomer CO15 is commercially available. Alternatively, it is readily

prepared from the acid-mediated reaction between acetone and 1,2,4-benzenetriol.[18]

Monomer 9,10-dimethyl-9,10-ethano-9,10-dihydro-2,3,6,7-tetrahydroxyanthracene (CO1;

Figure 2) was prepared following the procedure of Niederl and Nagel from pyrocatechol and

2,5-hexadione.[25] The carbocyclic structure of this monomer means it is more rigid than the

spirobisindane-based monomer 1 that has been used previously for PIM synthesis.[24]

Monomer CO19 (Figure 2) was prepared according to a patent procedure from pyrocatechol

and 2-butanone in 50% yield. [26, 27] It is formed as more than one isomer and shows

broadened signals in 1H-NMR for the -CH2- and CH3-groups, presumably due to their

restricted rotation due to crowding around the spiro centre. Monomer 3,3,3´,3´,4,4´-

hexamethyl-5,6,5´,6´-tetrahydroxy-1,1´-spirobisindane (CO2; Figure 3) is another simple

synthetic variation of spirobisindane 1 readily prepared from 3-methylpyrocatechol and

acetone in acetic and hydrobromic acids (yield 46%).[23] Monomer dibromo-5,5´,6,6´-

tetrahydroxy-3,3,3´,3´-tetramethyl-1,1´-spirobisindane (CO6) is the product of the

- 15 -

bromination of 1 in 1,4-dioxane. [23] The isomer of CO6 that is shown in Figure 3 (R1, R4 =

Br) is the major product (ca. 60%) of the bromination, the other isomer has most probably the

configuration R1, R3 = Br; the overall yield is about 90%.

Polymer preparation

All polymers were prepared from the various biscatechol monomers by reacting with a molar

equivalent of 2,3,5,6-tetrafluoroterephthalonitrile (2) with an excess of K2CO3. The basic

features of the synthesis of the homo- and co-polymers and their properties are listed in Table

1. Procedure I is based upon the original PIM-forming reaction in DMF carried out at low

temperature (~65 °C) over a period of 3-4 days.[12] Procedure II is based upon the rapid

synthesis of PIM-1 (0.5 to 2 h) in dimethylacetamide (DMAc) at temperatures of 150-160 °C,

as described by Guiver et al.[29] The precipitation of the polymer during the initial stages of

the reaction is avoided by the addition of toluene solvent to the DMAc. In a slight

modification, Procedure III used diethyl benzene (DEB) instead of toluene, which seems

advantageous because of its higher boiling point (150 °C).[23] Additional amounts of DEB

were added only when necessary to keep the mixture less viscous. In each case, the polymers

were separated by precipitation into water or methanol, if DEB was added and were purified

by re-precipitation from a suitable solvent into a mixture of MeOH/acetone or MeOH alone.

All polymers were characterized by 1H-NMR and IR spectroscopy and gave spectra that were

consistent with their expected structures. The composition of copolymers was estimated from

1H-NMR by integration of the peaks in the aromatic region and in each case this reflected

closely the monomer composition of the reaction (e.g., Figure 4). For those polymers that

proved soluble in CHCl3, Gel Permeation Chromatography (GPC) was used to estimate their

average molecular mass. For those polymers insoluble in CHCl3, their Mw was characterized

by inherent viscosity in CHCl3/TFA mixture (4:1) at 20 mg/cm³. Comparison of the measured

values of inherent and intrinsic viscosity (by GPC) of the CHCl3 soluble polymers showed a

good agreement (Table 1). Thermo-gravimetric analysis (TGA) of spirochromane polymers

- 16 -

and copolymers showed that the onset of decomposition is quite similar for each polymer and

is in the range 430-445 °C. PIM-CO19 shows higher onset of 477 °C comparable to PIM-1

(onset of 490°C) with its similar spirobisindane monomer without oxygen atoms.

The polymer prepared from monomers CO15 and 2 (PIM-CO15) following either Procedure

I or II is insoluble in CHCl3 but dissolves readily in dichlorobenzene and quinoline.

Following Procedure II a polymer with inherent viscosity of 0.51 dl/g is obtained which is

consistent with a value of Mw above 100,000 g/mol. The polymer prepared using Procedure I

demonstrated a lower inherent viscosity (0.36 dl/g) but still forms flexible, free-standing films

by casting from quinoline solution. Copolymers PIM1-CO15-75 and PIM1-CO15-50, were

prepared readily by either procedure II or III from monomer 2 and an equimolar amount of

biscatechol monomers CO15 and 1 in the ratio of 3:1 and 1:1, respectively. These copolymers

proved soluble also in CHCl3, which permitted analysis by GPC to demonstrate values of Mw

in excess of 100,000 g/mol. Copolymer compositions were confirmed by 1H-NMR signals of

the aromatic protons (Figure 4). Similarly, a comparison of the IR-spectra of the copolymers

(Figure S1) shows a distinct increase of the C-O stretching vibrations between 1100–1200

cm-1 with increasing content of CO15. Increasing the contribution of CO15 to the copolymer

composition to 85% resulted in a polymer that is insoluble in CHCl3.

Reaction mixtures containing equimolar ratios of monomer CO15 with modified

spirobisindane-based monomers such as CO2 (additional methyl group on each aromatic

ring), CO6 (additional bromine on each aromatic ring) and CO19 (alkyl substitution around

spirocyclic centre) also form copolymers of high Mw. The resulting copolymers PIMCO2-

CO15-50 and PIMCO19-CO15-50 are freely soluble in CHCl3 whereas bromine containing

PIMCO6-CO15-50 is insoluble in CHCl3 but soluble in dichlorobenzene.

Initial attempts to form the copolymer from a reaction mixture containing an equimolar ratio

of monomers CO15 and CO1 at 150 °C (procedure III) resulted in a copolymer (PIMCO1-

CO15-50) that was insoluble in CHCl3 and DCB but dissolved in CHCl3/TFA displaying an

- 17 -

inherent viscosity of 0.81 dl/g (suggesting Mw > 200000 g/mol). A similar reaction carried out

at lower temperature (100 °C) resulted in a PIMCO1-CO15-50 with an inherent viscosity of

0.33 dl/g, still insoluble in CHCl3 and THF, but that dissolved slowly in DCB and also

quinoline.

Gas permeation

Polymer solubility is a necessary property for the fabrication of integral asymmetric

membranes or thin film composite membranes. It is also necessary for the preparation of

solvent-cast films, which can be used for the determination of gas permeability. Typically,

defect-free, solvent-cast films were formed from THF or CHCl3, however, for polymers not

soluble in these solvents, films were obtained from dichlorobenzene or quinoline solutions.

Solutions in CHCl3/TFA did not form defect-free, homogeneous films probably due to phase

separation during evaporation caused by changes in the composition of the CHCl3/TFA.

Table 2 summarizes the gas permeability of the polymers and Table 3 the gas diffusivity. All

data are from methanol treated samples as specified in the experimental part. PIM-1 data

obtained from methanol treated samples are also included for comparison.[10] Relative to

PIM-1, the substitution of spirobisindane-based monomer 1 by spirochromane CO15 to give

polymer PIM-CO15 decreases the N2 permeability substantially from 600 to 40-80 Barrer.

Similar pro rata reductions in permeability are found for other gases. This is consistent with

the lower degree of intrinsic microporosity of PIM-CO15 as demonstrated by nitrogen

adsorption data obtained from a powdered sample of the polymer (see Figure S2) that

provides an apparent BET surface area of 510 m2 g-1, which is less than the value of 720 m2 g-

1 obtained for PIM-1.[10] The film cast from dichlorobenzene (PIM-CO15(a), Table 2)

displays higher permeability than that cast from quinoline, PIM-CO15(b). Both films did not

contain any traces of the solvent, as checked by TGA. The difference may be attributed to

closer packed chains in the final film obtained from the better solvent quinoline. As might be

- 18 -

expected, the copolymers PIM1-CO15-75 and PIM1-CO15-50 demonstrate values for gas

permeability and diffusivity mid-way between those of PIM-1 and PIM-CO15. The gas

permeabilities of copolymers PIMCO2-CO15-50 and PIMCO6-CO15-50 are roughly

similar to those of PIM1-CO15-50. The additional methyl groups in PIM-CO19 seems to

block diffusivity for gas molecules as compared to PIM-1 with roughly a two-fold decrease in

diffusivity and lower permeability (Tables 2 and 3/Figure 5 and 6). Analogous behavior was

previously found for polyacetylenes with the substitution of only one methyl group in

polytrimethylsilylpropyne (PTMSP) by ethyl (Figure S3) resulted in a six-fold decrease in

oxygen permeability.[30] Commensurate with the permeability-selectivity trade-off, the

permselectivities of the polymers are enhanced relative to PIM-1 (Figure 5; Table S1), for

example, the permselectivity for CO2 over N2 increases gradually from 18 (PIM-1) to 27 for

the PIM-CO15(a) (film cast from quinoline). However, all data points lie below the updated

Robeson upper bounds,[7] which for some gas pairs are partly delineated by the data for PIM-

1 (e.g. CO2/N2; Figure 5), nevertheless, they lie comfortably above the original Robeson

upper bound for some important gas pairs (e.g. CO2/CH4).[6]

Helium is the smallest gas molecule with always the lowest solubility and can be taken as a

marker for diffusivity and indirectly for free volume, therefore, information about the

contribution of solubility to the overall CO2 permeability of the polymers can obtained by the

plot of He-diffusivity against CO2-solubility (Figure 6). It can be seen that two polymers,

PIMCO6-CO15-50 and PIMCO1-CO15-50, display higher solubility coefficients for CO2

than PIM-1, with values of 0.75 and 0.82 cm³ (STP)/cm³ cmHg, respectively (Table S2).

These values are remarkable as PIM-1 was previously shown to possess the highest solubility

coefficients of all polymers investigated so far for gas permeability with a value for CO2 of

0.70 cm³/cm³ cmHg.[10] The polar and polarisable bromines may account for the enhanced

solubility of CO2 in PIMCO6-CO15-50, whereas for PIMCO1-CO15-50, the combination

of the rigid ethanoanthracene unit from CO1 with the polarity of the additional oxygen atoms

- 19 -

of the spirobischromane from CO15 results in even higher CO2-solubility. All other polymers

demonstrate values between 0.6 and 0.7 cm³ (STP)/cm³ cmHg. For comparison, the highly

permeable microporous polyacetylene PTMSP demonstrates values for CO2-sorption of 0.13

(fresh film) and 0.05 cm³ cm-³ cmHg-1 (aged film).[31] A plot of CO2-diffusivity versus CO2-

solubility looks very similar and is shown in Figure S4 together with a plot of CO2-diffusivity

versus CO2-permeability (Figure S5). All gas permeation measurements were done with thick

polymer films around 100 µm. The permselectivity was stable over some weeks, however, for

very thin films a decrease in permeability accompanied by increase in selectivity is expected

but was not a task of this first report on new PIM materials.

Conclusions

In conclusion, the substitution of the spirobisindane unit of PIM-1 with the spirochromane

unit results in polymers of lower overall permeability but enhanced selectivity for a number of

gas pairs. Similar reductions in permeability but increases in selectivity were found by

Guiver et al. for a range of PIM copolymers containing binaphthyl, thianthrene or disulphone-

based monomers.[32-34] However, two co-polymers containing the spirochromane component

demonstrate remarkably high solubility coefficients for CO2 even compared to the value for

PIM-1. Hence, although unlikely to provide a significant improvement over PIM-1 for

separation involving permanent gases, these two polymers may provide greater selectivities

for membrane separations involving condensable gases and vapors due to the enhanced

contribution of solubility to their overall permeability.[16] Studies to confirm this possibility

are planned.

Acknowledgement:

We thank Dr. Thomas Emmler for taking the NMR-spectra and help with their interpretation.

Silke Dargel and Silvio Neumann are thanked for synthesis of the monomers and polymers.

- 20 -

Received: ((will be filled in by the editorial staff)); Revised: ((will be filled in by the editorial

staff)); Published online: DOI: 10.1002/macp.#########

Keywords: gas permeability; intrinsic microporosity; PIM; polycondensation; polymer

membranes

[1] N. W. Ockwig, T. M. Nenoff, Chem. Rev. 2007, 107, 4078.

[2] L. Shao, B. T. Low, T. S. Chung, A. R. Greenberg, J. Membr. Sci. 2009, 327, 18.

[3] X. Feng, J. Ivory, J. Membr. Sci. 2000, 176, 197.

[4] P. Bernardo, E. Drioli, G. Golemme, Ind. Eng. Chem. Res. 2009, 48, 4638.

[5] L. Zhao, E. Riensche, L. Blum, D. Stolten, J. Membr. Sci. 2010, 359, 160.

[6] L. M. Robeson, J. Membr. Sci. 1991, 62, 165.

[7] L. M. Robeson, J. Membr. Sci. 2008, 320, 390.

[8] P. M. Budd, N. B. McKeown, Polym. Chem. 2010, 1, 63.

[9] B. D. Freeman, Macromolecules 1999, 32, 375.

[10] P. M. Budd, N. B. McKeown, B. S. Ghanem, K. J. Msayib, D. Fritsch, L. Starannikova,

N. Belov, O. Sanfirova, Y. P. Yampol'skii, V. Shantarovich, J. Membr. Sci. 2008, 325, 851.

[11] P. M. Budd, B. S. Ghanem, S. Makhseed, N. B. McKeown, K. J. Msayib, C. E.

Tattershall, Chem. Commun. 2004, 230.

[12] P.M. Budd, E.S. Elabas, B.S. Ghanem, S. Makhseed, N. B. McKeown, K. J. Msayib, C.

E. Tattershall, D. Wang, D., Adv. Mater. 2004, 16, 456.

[13] P. M. Budd, K. J. Msayib, C. E. Tattershall, B. S. Ghanem, K. J. Reynolds, N. B.

McKeown, D. Fritsch, J. Membr. Sci. 2005, 251, 263.

[14] C. L. Staiger, S. J. Pas, A. J. Hill, C. J. Cornelius, Chem. Mat. 2008, 20, 2606.

[15.] J. Song, N. Du, Y. Dai, G.P. Robertson, M.D. Guiver, S. Thomas, I. Pinnau,

Macromolecules 2008, 41, 7411.

- 21 -

[16] S. Thomas, I. Pinnau, N. Y. Du, M. D. Guiver, J. Membr. Sci. 2009, 333, 125.

[17] S. Thomas, I. Pinnau, N. Y. Du, M. D. Guiver, J. Membr. Sci. 2009, 338, 1.

[18] W. Baker, D. M. Besly, J. Chem. Soc. 1939, 195.

[19] J. Pospisil, L. Kotulak, L. Taimr, Eur. Polym. J. 1971, 7, 255.

[20] F. Pfeiffer, N. M. Felix, C. Neuber, C. K. Ober, H.-W. Schmidt, Phys. Chem. Chem.

Phys. 2008, 10, 1257.

[21] N. Felix, K. Tsuchiya, C. M. Y. Luk, C. K. Ober, Proc. SPIE-Int. Soc. Opt. Eng. 2006,

6153, 61534B/1.

[22] N. B. McKeown, P. M. Budd, Macromolecules 2010, 43, 5163.

[23] D. Fritsch, K. Heinrich, G. Bengtson, PMSE Prepr. 2009, 101, 761.

[24] T. Emmler, K. Heinrich, D. Fritsch, P. M. Budd, N. Chaukura, D. Ehlers, K. Ratzke, F.

Faupel, Macromolecules 2010, 43, 6075.

[25] J. B. Niederl, R. H. Nagel, J. Am. Chem. Soc. 1940, 62, 3070.

[26] S. Sakaguchi, S. Tan (Fuiji Photo Film Co. Ltd.) EP. 0307951 1989.

[27] H. Gotou (Fiji Photo Film Co Ltd.) JP 2286642 1990.

[28] R. Fabinyi, T. Szeky, Ber. Dtsch. chem. Ges. 1905, 38, 2307.

[29] N. Du, G. P. Robertson, I. Pinnau, S. Thomas, M. D. Guiver, Macromol. Rapid Commun.

2009, 30, 584.

[30] K. Nagai, T. Masuda, T. Nakagawa, B. D. Freeman, I. Pinnau, Prog. Polym. Sci. 2001,

26, 721.

[31] V. Bondar, A. Alentiev, T. Masuda, Y. Yampolskii, Macromol. Chem. Phys. 1997, 198,

1701.

[32] N. Du, G. P. Robertson, I. Pinnau, M. D. Guiver, Macromolecules 2010, 43, 8580.

[33] N. Du, G. P. Robertson, J. Song, I. Pinnau, S. Thomas, M. D. Guiver, Macromolecules

2008, 41, 9656.

- 22 -

[34] N. Du, G. P. Robertson, J. Song, I. Pinnau, M. D. Guiver, Macromolecules 2009, 42,

6038.

Figure 1. The synthesis of PIM-1. Reagents and conditions. i. K2CO3, DMF, 65 °C, 96 h (or

160 °C; 0.5 h).

OH

OH

OH

OH

F

F F

F

CN

CN

O

O *

*

CN

CN

O

O*

*

n

+

1 2 PIM-1

i.

Figure 2. Structure of Monomers CO15, CO1 and CO19.

OH

OH

O

OH

OH

OOH

OH OH

OHOH

OH

OH

OH

CO15 CO1 CO19

Figure 3. Structure of Monomers CO2 and CO6.

OH

OH

OH

OH

R1

R2

R3

R4

CO2: R1=R4=Me; R2=R3=HCO6: R1=R4=Br; R2=R3=H

- 23 -

Figure 4. Comparison of the 1H-NMR peaks of the aromatic protons for PIM-1, PIM-CO15

and the two copolymers prepared from monomer 1 and spirobischromane monomer CO15,

PIM1-CO15-50 and PIM1-CO15-75. Integration of the peaks confirms that the composition

of the copolymer reflects closely the monomer ratio used in the polymerization reaction.

- 24 -

Figure 5. CO2 permeability versus CO2/N2 permselectivity. For notation see Table 1. The line

represents Robeson’s updated upper bound. [7]

P

IM-C

O15

(a

)

PIM

-CO

15 (

b)

PIM

1-C

O1

5-75

PIM

1-C

O1

5-50

PIM

CO

2-C

O1

5-50

PIM

CO

19-

CO

15-5

0

.

PIM

CO

6-C

O1

5-50

(b

)

PIM

-CO

19

PIM

-1

0 2000 4000 6000 8000 10000 12000

CO2-Permeability, Barrer

0

10

20

30

40

CO

2/N

2-S

ele

ctiv

ity,

-

PIM

CO

1-C

O1

5-5

0 (

a)

- 25 -

Figure 6. Helium diffusion coefficient as free volume marker versus CO2 solubility

coefficient. For notations see Table 2, 3.

PIM-CO15 (a)

PIM-CO15 (b)

PIM1-CO15-75

PIM1-CO15-50

PIMCO2-CO15-50.

PIMCO1-CO15-50 (a)

PIMCO6-CO15-50 (b)

PIM-CO19

PIM-1

1000 2000 3000 4000 5000 6000 7000 8000

He-Diffusivitiy x 10^8, cm²/s

0.55

0.60

0.65

0.70

0.75

0.80

0.85

CO

2-S

olub

ility

, cm

³/cm

³ cm

Hg

PIMCO19-CO15-50

- 26 -

Table 1. Preparation conditions and properties of the polymers.

Polymera Procedureb Time[h]

Yield [%]

Mwc Intr.

visc.d [cm³/g]

Inh. visc.e [cm³/g]

Degradation Onset.f [°C]

PIM-CO15 II 0.5 98 n.s.g n.s. 51 430

PIM-CO15 I 96 96 n.s. n.s. 36 418

PIM1-CO15-75 II or III 1.0 86 125000 50 54 -i

PIM1-CO15-50 II 0.9 99 195000 75 72 445

PIMCO1-CO15-50(a) III 0.5 96 n.s. n.s. 81 437

PIMCO1-CO15-50(b) IIIh 0.5 79 n.s. n.s. 33 -i

PIMCO2-CO15-50 II 1.3 96 112000 50 57 445

PIMCO6-CO15-50 III 0.5 52 n.s. n.s. 42 434

PIMCO19-CO15-50 III 0.5 94 86000 40 42 442

PIM-CO19 III 1.0 95 72000 30 37 477

aEach polymer is defined by the catechol monomer(s) from which they were made. For the copolymers, the percentage of the contribution of monomer CO15 to the total of the biscatechol monomer composition is given at the end of the name.

bSee discussion for details of each type of polymerization procedure. cFrom GPC analysis with calibration by polystyrene standards.

dIntrinsic viscosity from GPC measurement.

eInherent viscosity measured in CHCl3/TFA (4/1 v/v) at 20 mg polymer/cm³.

fOnset of degradation measured by TGA.

gn.s. indicates that the polymer is not soluble in an appropriate solvent for GPC (i.e. CHCl3).

hReaction carried out at 100 °C rather than the standard 150 °C used for procedure III.

iNot measured.

- 27 -

Table 2. Gas permeability of the polymers at 30°C.

Polymer P(N2)

[Barrer]

P(O2)

[Barrer]

P(He)

[Barrer]

P(H2)

[Barrer]

P(CO2)

[Barrer]

P(CH4)

[Barrer]

PIM-CO15(a) 40 150 330 600 1070 56

PIM-CO15(b) 83 275 450 900 2000 130

PIM1-CO15-75 110 350 520 1100 2570 180

PIM1-CO15-50 210 630 770 1700 4600 370

PIMCO1-CO15-50(a) 240 760 870 2100 5400 350

PIMCO2-CO15-50 260 790 950 2150 5300 430

PIMCO6-CO15-50(b) 170 520 650 1500 3800 280

PIMCO19-CO15-50 150 460 620 1300 3400 260

PIM-CO19 320 820 880 2100 6100 580

PIM-110 610 1530 1320 3300 11200 1160

Films were cast from CHCl3 except: (a) quinoline, (b) dichlorobenzene. Thickness 80 to 100 µm. P is permeability coefficient; units: 1 Barrer = 10-10 cm3 [STP] cm cm-2 s-1 cmHg-1 = 3.35×10-16 mol m m-2 s-1 Pa-1.

Table 3. Diffusion coefficients of the polymers at 30°C.

Polymer D(N2) D(O2) D(He) D(H2) D(CO2) D(CH4)

PIM-CO15 (a) 13 45 2200 1100 17 4.2

PIM-CO15 (b) 25 76 2600 1500 30 9.1

PIM1-CO15-75 38 110 3300 2000 44 14

PIM1-CO15-50 65 170 4300 2800 68 26

PIMCO1-CO15-50 (a) 55 170 4100 2900 66 19

PIMCO2-CO15-50 73 200 4400 3150 82 28

PIMCO6-CO15-50 (b) 43 120 3200 2200 51 16

PIMCO19-CO15-50 47 120 3300 2100 53 18

PIM1-CO19-100 87 210 4100 2900 89 37

PIM-110 160 390 6800 5000 160 71

Films were made from CHCl3 except: (a) quinoline, (b) dichlorobenzene. Thickness 80 to 100 µm. D is diffusion coefficient given in 10-8 cm² s-1.

- 28 -

New polymers and co-polymers of intrinsic microporosity (PIM) were synthesized to

yield high molecular weight, flexible films forming polymers. Their properties, i.e., gas

permeation and separation properties were analyzed. Compared to the archetype PIM-1 lower

permeabilities at higher selectivities for the gases were detected. A remarkable high solubility

for CO2 for some polymers was found exceeding the solubility of PIM-1 and PIM-type

polyacetylenes.

G. Bengtson, M. Carta, N. B. McKeown, D. Fritsch* Title Synthesis and Gas Permeation Properties of Spirobischromane-Based Polymers of Intrinsic

Microporosity.

- 29 -

Copyright WILEY-VCH Verlag GmbH & Co. KGaA, 69469 Weinheim, Germany, 2011.

Supporting Information for Macromol. Chem. Phys., DOI: 10.1002/ macp.######### Synthesis and Gas Permeation Properties of Spirobischromane-Based Polymers of Intrinsic Microporosity.

Detlev Fritsch*, Gisela Bengtson, Mariolino Carta2 and Neil B. McKeown2 Figure S1. FT-IR (ATR) spectra of PIM polymers with increasing amount of CO15.

- 30 -

Figure S2. Nitrogen adsorption data of PIM-CO15 prepared by procedure 1, see Table 1 in

the full paper.

Spiro bischromane polymer

0

50

100

150

200

250

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

P/Po

v (A

DS

) cc

/g

Figure S3. Structures of ultrapermeable polyacetylenes.

*

R'

*

R

n

3 R=Me, R'=Me3 =PTMSP4 R=Me, R'=SiMe2Et

- 31 -

Figure S4. A Plot of CO2 diffusivity with CO2-solubility at 30°C.

PIM-CO15 (a)

PIM-CO15 (b)

PIM1-CO15-75

PIM1-CO15-50

PIMCO2-CO15-50PIMCO19-CO15-50

PIMCO1-CO15-50

PIMCO6-CO15-50 (b)

PIM-CO19

PIM-1

0 50 100 150 200

CO2-Diffusivity x 10^8, cm²/s

0.55

0.60

0.65

0.70

0.75

0.80

0.85

CO

2-S

olu

bili

ty,

cm³/

cm³

cmH

g

Figure S5. A plot of CO2 diffusivity with CO2 permeability at 30°C.

PIM

-CO

15 (

a)

PIM

-CO

15 (

b)

PIM

1-C

O1

5-75

PIM

1-C

O1

5-50

PIM

CO

2-C

O1

5-50

.

PIM

CO

1-C

O1

5-50

PIM

CO

6-C

O1

5-50

(b

)

PIM

-CO

19

.

0 50 100 150 200

CO2-Diffusivity x 10^8, cm²/s

0

2000

4000

6000

8000

10000

12000

CO

2-P

erm

eabi

lity,

Ba

rre

r

PIM

CO

19-C

O15

-50

- 32 -

Table S1. Permselectivities of the polymers to various gases at 30°C.

Notation P(O2/N2) P(He/N2) P(H2/N2) P(CO2/N2) P(CO2/CH4) D(CH4/N2)

PIM-CO15 (a) 3.8 8.2 15.0 26.8 19.2 0.31 PIM-CO15 (b) 3.3 5.4 10.9 24.1 15.3 0.36 PIM1-CO15-75 3.2 4.7 9.7 23.4 14.4 0.37 PIM1-CO15-50 3.0 3.7 8.2 21.6 12.5 0.40 PIMCO2-CO15-50 3.0 3.6 8.2 20.2 12.4 0.38 PIMCO19-CO15-50 3.0 4.0 8.7 22.1 13.0 0.38 PIMCO1-CO15-50 3.2 3.6 8.6 22.4 15.4 0.34 PIMCO6-CO15-50 (b)

3.1 3.9 8.8 22.7 13.7 0.38

PIM-CO19 2.6 2.8 6.5 19.2 10.4 0.43 PIM-1 3.3 2.2 5.4 18.4 9.7 0.44

Films were made from CHCl3 except: (a) chinolin, (b) dichlorobenzene. Thickness 80 to 100 µm.

P(x/y) = Permeability-Selectivity; D(x/y) = Diffusion-Selectivity.

Table S2. Solubility data of the polymers from time-lag measurement at 30°C.

Notation SN2 SO2 SHe SH2 SCO2 SCH4

PIM-CO15 (a) 30 33 1.5 5.5 632 133 PIM-CO15 (b) 33 36 1.7 6.0 674 144 PIM1-CO15-75 29 33 1.6 5.4 582 127 PIM1-CO15-50 33 37 1.8 6.2 669 143 PIMCO2-CO15-50 36 39 2.2 6.8 646 155 PIMCO19-CO15-50 33 37 1.9 6.4 651 146 PIMCO1-CO15-50 44 45 2.1 7.0 817 184 PIMCO6-CO15-50 (b) 39 42 2.0 6.7 749 170 PIM-CO19 37 40 2.2 7.2 685 157 PIM-1 37 39 1.9 6.6 700 163

Solubility (S) x 10³, cm³ cm-³ cmHg-1. Films were made from CHCl3 except: (a) quinoline, (b) dichlorobenzene. Thickness 80 to 100 µm.