Porous films comprising metal-organic framework materials

Abstract

The present invention relates to porous films comprising (A) from 51 wt.-% to 99.9 wt.-% based on the total weight of the film of at least one porous metal-organic framework material, the material comprising at least one at least bidentate organic compound coordinated to at least one metal ion; (B) from 0.1 wt.-% to 49 wt.-% based on the total weight of the film of at least one fibrillated fluoropolymer; and (C) 0 wt.-% to 48.9 wt.-% based on the total weight of the film of an additive component. The invention further relates to a composition for preparing such a film and its use.

Claims

1. A porous film comprising (A) from 51 wt.-% to 99.9 wt.-% based on the total weight of the film of at least one porous metal-organic framework material, the material comprising at least one at least bidentate organic compound coordinated to Al; (B) from 0.1 wt.-% to 49 wt.-% based on the total weight of the film of at least one fibrillated fluoropolymer; and (C) 0 wt.-% to 48.9 wt.-% based on the total weight of the film of an additive component, wherein the film is freestanding and flexible; and wherein the film has a specific surface area of at least 250 m.sup.2/g measured according to BET and a volumetric specific surface area of at least 15 m.sup.2/cm.sup.3.

2. The film of claim 1, wherein the at least one fibrillated fluoropolymer is selected from the group of polymers and copolymers consisting of trifluoroethylene, hexafluoropropylene, monochlorotrifluoroethylene, dichlorodifluoroethylene, tetrafluoroethylene, perfluorobutyl ethylene, perfluoro(alkyl vinyl ether), vinylidene fluoride, and vinyl fluoride and blends thereof.

3. The film of claim 2, wherein the at least one fibrillated fluoropolymer is a fibrillated polytetrafluoroethylene.

4. The film of claim 1, wherein the film has a thickness of at least 0.5 m.

5. The film of claim 1, wherein the film has a two-dimensional surface with at least one dimension which exceeds 1 cm.

6. The film of claim 1, wherein the specific surface area of the film measured according to BET is at least 500 m.sup.2/g.

7. The film of claim 1, wherein the volumetric specific surface area of the film is at least 506 m.sup.2/cm.sup.3.

8. The film of claim 1, wherein the amounts based on the total weight of the film are 51 wt.-% to 99.9 wt.-% of (A), 0.1 wt.-% to 49 wt.-% of (B) and 0 wt.-% of (C).

9. The film of claim 1, wherein the amounts based on the total weight of the film are 51 wt.-% to 99.8 wt.-% of (A), 0.1 wt.-% to 48.9 wt.-% of (B) and 0.1 to 48.9 wt.-% of (C).

10. The film of claim 1, wherein the at least one at least bidentate organic compound is derived from a di-, tri- or tetra carboxylic acid or substituted or unsubstituted ring systems: ##STR00003##

11. The film of claim 1, wherein the at least one at least bidentate organic compound is derived from fumaric acid.

12. The film of claim 1, wherein the additive component comprises at least one additive selected from the group consisting of electrically or thermally conducting particles, thermoplastic polymers, liquids, surfactants, dispersants, antioxidants, UV absorbers/light stabilizers, metal deactivators, antistatic agents, reinforcing agents, fillers, nucleating agents, antifogging agents, biocides, plasticisers, lubricants, emulsifiers, colorants, pigments, rheology additives, mold release agents, tackifiers, catalysts, flow-control agents, optical brighteners, flameproofing agents, antidripping agents, and blowing agents.

13. A sensor, a conductive film, a storage or separation device which comprises the film as claimed in claim 1.

14. A chemical reaction which comprises the film as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the increase of the weight of a film of the invention as a function of the exposure to ambient atmosphere.

(2) FIG. 2 shows a heating a cooling cycle of a film of the invention as a function of the time when subjecting to electric power (heating cycle) and after termination of current flow (cooling cycle).

(3) FIG. 3 shows the water adsorption of a film according to the invention as a function of the relative humidity.

EXAMPLES

Example 1: Fabrication of a Metal-Organic Framework Material (MOF) Film (Copper Benzenetricarboxylate MOF, C300)

(4) 900 mg of commercially available metal-organic framework powder (Basolite C300, BASF SE) and 100 mg of poly(tetrafluoroethylene) powder (DuPont, Teflon 6CN X-EF) were placed in a mortar and mixed. By this, weight percentages based on the total weight of the film of 90% (A) and 10% (B) were adjusted.

(5) After an Intimate powder mixture was obtained pressure then was applied to the pestel in order to induce fibrillation of the poly(tetrafluoroethylene) component.

(6) After a homogenous light blue putty-like mass was obtained the obtained material was transferred to a calender and formed into a free-standing flexible film. The gap of the calender was used to progressively decrease the thickness of the film to a final level of 300 m as determined by a thickness gage (Digimatic Indicator TYPE ID-110M, Mitutoyo). The obtained light blue film was trimmed into a rectangular geometry (2.6 cm2.4 cm) with a blade and its weight was determined to be 213.6 mg using a laboratory balance. The film density can thus be calculated and was found to be 1.14 g/cm.sup.3

(7) The specific surface area of the film was 361 m.sup.2/g measured by nitrogen physisorption at 196.15 C. (Gemini V 2365, Micromeritics) and calculated using the Brunauer-Emmett-Teller method (according to DIN ISO 9277:2003-05). Using the film density the volumetric specific surface area of the film was calculated to be 412 m.sup.2/cm.sup.3.

Example 2a: Fabrication of a Thin MOF Film (Aluminum Fumarate MOF, A520)

(8) The same procedure and equipment as in Example 1 was used.

(9) 276 mg of commercially available metal-organic framework powder (Basolite A520, BASF SE) and 31.2 mg of poly(tetrafluoroethylene) powder (DuPont, Teflon 6CN X-EF) were used resulting in weight percentages based on the total weight of the film of 90% (A) and 10% (B).

(10) A free-standing flexible white film with a thickness of 52 m and a film density of 1.20 g/cm.sup.3 was obtained. The specific surface area of the film was 422 m.sup.2/g and the volumetric specific surface area of the film was calculated to be 506 m.sup.2/cm.sup.3.

Example 2 b Fabrication of a Thick MOF Film (Aluminum Fumarate MOF, A520)

(11) The same procedure and equipment as In Example 1 was used. 950 mg of commercially available metal-organic framework powder (Basolite A520, BASF SE) and 50 mg of poly(tetrafluoroethylene) powder (DuPont, Teflon 6CN X-EF) were used resulting In weight percentages based on the total weight of the film of 95% (A) and 5% (B).

(12) A free-standing flexible white film with a thickness of 345 m and a film density of 0.78 g/cm.sup.3 was obtained. The specific surface area of the film was 738 m.sup.2/g and the volumetric specific surface area of the film was calculated to be 576 m.sup.2/cm.sup.3.

Example 3: Fabrication of a Mixed MOF Film (C300/A520)

(13) The same procedure and equipment as In Example 1 was used.

(14) 254.0 mg of metal-organic framework powder 1 (Basolite C300, BASF SE), 254.4 mg of metal organic framework powder 2 (Basolite A520, BASF SE) and 27.1 mg of poly(tetrafluoroethylene) powder (DuPont, Teflon 6CN X-EF) were resulting in weight percentages based on the total weight of the film of 47.4% (Al), 47.5% (A2) and 5.1% (B). Thus the weight percentage of component (A) Is 94.9%.

(15) A free-standing flexible light blue film with a thickness of 95 m and a film density of 1.05 g/cm.sup.3 was obtained. The specific surface area of the film was 180 m.sup.2/g and the volumetric specific surface area of the film was calculated to be 189 m.sup.2/cm.sup.a.

Example 4: Fabrication of a ZIF 8 Film (Zinc 2-Methylimidazolate MOF, Z1200)

(16) The same procedure and equipment as in Example 1 was used.

(17) 478.2 mg of commercially available metal-organic framework powder (Basolite Z1200, BASF SE) and 25.1 mg of poly(tetrafluoroethylene) powder (DuPont, Teflon 6CN X-EF) were used resulting in weight percentages based on the total weight of the film of 95% (A) and 5% (B).

(18) A free-standing flexible white film with a thickness of 51 m and a film density of 0.72 g/cm.sup.3 was obtained. The specific surface area of the film was 1068 m.sup.2/g and the volumetric specific surface area of the film was calculated to be 769 m.sup.2/cm.sup.3.

Example 5: Fabrication of a MOF/Carbon Black Composite Film

(19) The same procedure and equipment as in Example 1 was used.

(20) 453.0 mg of metal-organic framework powder (Basolite C300, BASF SE), 61.2 mg of poly(tetrafluoroethylene) and 90.8 mg of carbon black (Printex XPB 538, Orion Engineered Carbons) powder (DuPont, Teflon 6CN X-EF) were used resulting in weight percentages based on the total weight of the film of 75% (A), and 10% (B) and 15% (C).

(21) A free-standing flexible black film with a thickness of 115 m and a film density of 1.4 g/cm.sup.3 was obtained.

Example 6: Fabrication of a MOF Humidity Sensor

(22) The light blue film obtained in Example 1 was placed into a vacuum drying chamber for 15 minutes at 80 C. It was found that desorption of adsorbed humidity resulted in the activation of the metal-organic framework component of the film. During this process the film changed its color from light blue into dark blue. The film was quickly transferred to a laboratory balance and the balance was tared. Over a few minutes a continuous increase in weight was observed due to the re-adsorption of humidity from the ambient atmosphere while the film changed again its color to light blue. FIG. 1 shows the weight increase of the film within a time frame of approximately 1 to 1.5 hours. The effect was found to be fully reversible over a repeated number of adsorption/desorption cycles.

Example 7: Fabrication of a Heatable MOF/Carbon Black Film (Combined Electrical/Thermal Sensor)

(23) The film obtained in Example 5 was trimmed into a rectangular geometry (2.1 cm1.0 cm). An electrically conductive silver paint (Dosilac, Amidoduco) was coated around two opposite edges of the film and thin metal contacts (nickel foil, Alfa Aesar, 30 m) were glued onto the film.

(24) The metal contacts of the film were connected with two alligator clips in series to a multimeter (Metrahit, GMC-I Gossen-Metrawatt GmbH, Nrnberg/Germany) and a laboratory voltage source (EA-PS 3016-40 B, Elektro-Automatik GmbH, Viersen/Germany). A voltage of 16 V was adjusted and electrical current was allowed to flow through the film.

(25) The resulting average electrical power was determined by the multimeter to be 41 mA. By this, the electrical resistance was calculated to be 387 Ohm.

(26) The temperature of the film was measured by a contactless infrared camera (FLIR i60, Orglmeister Infrarot-Systeme, Walluf/Germany) which was also used to visualize the heating of the film.

(27) An average temperature level of 85.7 C. was achieved after 97 s. Once the voltage was cut the temperature decreased again to 26.5 C. after 136 s. FIG. 2 shows the respective curves of temperature increase (heating cycle) and decrease (cooling cycle).

(28) The effect was found to be fully reversible over a repeated number of heating/cooling cycles.

Example 8: Application of a MOF Film as Recyclable Drying Agent

(29) The water uptake of the film obtained from example 2a was measured as the increase in weight over that of the dry film. The water adsorption/desorption isotherm was performed on a VTI SA instrument from TA Instruments following a step-isotherm program. The experiment consisted of a run performed on a sample material that has been placed on the microbalance pan inside of the instrument. Before the measurement was started, the residual moisture of the sample was removed by heating the sample to 100 C. (heating ramp of 5 C./min) and holding it for 6 h under a nitrogen flow. After the drying program, the temperature in the cell was decreased to 25 C. and kept isothermal during the measurement. The microbalance was calibrated, and the weight of the dried sample was balanced (maximum mass deviation 0.01 wt.-%). Water uptake by the sample was measured as the increase in weight over that of the dry sample. First, as adsorption curve was measured by increasing the relative humidity (RH) (expressed as wt.-% water in the atmosphere inside of the cell) to which the sample was exposed and measuring the water uptake by the sample as equilibrium. The RH was increased with a step of 10 wt.-% from 5% to 85% and at each step the system controlled the RH and monitored the sample weight until reaching the equilibrium conditions after the sample was exposed from 85 wt.-% to 5 wt.-% with a step of 10% and the change in the weight of the sample (water uptake) was monitored and recorded.

(30) The total water uptake by weight at RH 85% was 30%. The water isotherm is displayed in FIG. 3. The shape of the isotherm demonstrates a reversible water-uptake and release behaviour of the MOF film, a prerequisite for the usage as recyclable drying agent.

Example 9: Fabrication of a Large MOF Film and a MOF Roll for Gas Storage

(31) 232.6 g of metal-organic framework powder (Basolite C300, BASF SE), 5.96 g of poly(tetrafluoroethylene) powder (DuPont, Teflon 6CN X-EF) and 20 agate grinding beads (diameter 2.0 cm, equal to 208.0 g) were placed in a 1000 mL plastic vessel. By this, a weight ratio of 97.5/2.5 of metal-organic framework to poly(tetrafluoroethylene) was adjusted.

(32) The sealed plastic vessel was treated for 12 h on a pair of cylindrical rollers. Thereby an intimate powder mixture was obtained. The mixture was transferred in portions to a mortar where it was further mixed. Complete fibrillation of the poly(tetrafluoroethylene) component was achieved by application of pressure to the pestel.

(33) The resulting homogenous light blue putty-like mass was transferred to a calender and formed into a free-standing flexible film (0.75 mm thickness) which was trimmed into a strip-like geometry with a blade (14.5 cm width160 cm length, total film weight before drying 145.1 g, total film weight after drying 110.8 g). Two strips of plastic fabric (4.5 g) were cut into the same dimension and placed on top and below of the MOF film. After this, the three layers were tightly wrapped into a roll-like geometry which was fixed with scotch tape (0.3 g) such that the plastic fabric separated the MOF layers from each other. The diameter of the roll was 4.5 cm. The film density was calculated to be 0.64 g/cm.sup.3. Upon vacuum drying at 80 C. It was found that the color of the roll changed from light blue into dark blue.

(34) The gravimetric specific surface area of the film was 924 m.sup.2/g and the volumetric specific surface area of the film was calculated to be 588 m.sup.2/cm.sup.3.

(35) Uptake of Methane

(36) The uptake of methane was measured in the following way:

(37) The obtained roll was placed in a steel container which was tightly sealed, followed by evacuation at oil pump vacuum. The container was then placed in an overhead container and connected to a methane pressure reservoir. A certain pressure of methane was applied by opening a valve connected to the steel container. The valve was closed and the weight of the complete container was measured as soon as no change in temperature was observable anymore (21 C., isotherm). The data are shown in the following Table:

(38) TABLE-US-00002 absolute pressure container [bar] CH.sub.4 uptake [g CH.sub.4/L Tank] 0 0 5.2 22.47 11.60 37.81 15.40 43.81 20.00 50.25 24.00 55.99 51.30 77.56 101.50 112.71 152.20 143.24 200.40 169.24

Example 10: Quantification of Reversible Water Adsorption and Desorption with Heatable MOF/Carbon Black Film

(39) According to the procedure given in Example 5, a MOF/Carbon Black film of identical composition was prepared with a final thickness of 63 m and a weight of 24 mg. It was trimmed into a rectangular geometry (2.1 cm1.4 cm). An electrically conductive silver paint (Dosilac, Amidoduco) was coated around two opposite edges of the film and thin metal contacts (nickel foil, Alfa Aesar, 30 m) were glued onto the film. The metal contacts of the film were connected with two thin copper wires in series to a multimeter (Metrahit, GMC-I Gossen-Metrawatt GmbH, Nrnberg/Germany) and a laboratory voltage source (EA-PS 3016-40 B, Elektro-Automatik GmbH, Viersen/Germany). The film was put onto a sample holder which was placed itself on a laboratory balance.

(40) By this experimental setup the weight change of the film was monitored as a function of applied voltage and hence increase or decrease in temperature. As a result humidity adsorbed within the film was desorbed within short time (<2 min) when the voltage (16 V) was switched on (average temperature of the film 74 C.). After desorption of the total humidity contained in the film its weight remained constant. After the voltage was switched off the weight of the film recovers to the original level due to re-adsorption of humidly from the ambient air. The process was found to be fully reversible and revealed good reproducibility. The amount of humidity which could be adsorbed and desorbed corresponds to approximately 10 wt-% with respect to the total weight of the film.