Toward nanoporous composite membranes with tailored block copolymers as selective layer

Transcription

1 Research Topic: Toward nanoporous composite membranes with tailored block copolymers as selective layer By Marcel Gawenda

2 Outline of the presentation: 1. Motivation of the project 2. Concept of the project and basics 3. Characterization of the membrane 4. Preparation and Characterization of thin polymer films 5. Preparation of the composite membrane 6. Outlook 7. Acknowledgements

3 1. Motivation synthetic membranes featuring transport selectivity for molecules different from water nature: highly specific transport through biological membranes, based on molecular recognition processes within macromolecular assemblies AIM: Development and characterization of novel synthetic membranes with pore diameters of 2 to 20 nm

4 exploiting the self-assembly properties of binary or ternary block copolymers to adjust the morphology of the phasesegregated microdomains Special Aim permeability can be reversibly switched by external stimuli such as change of temperature (PNIPAM) or ph (P2VP)

5 Campus Essen Characterization of support membranes (Gawenda/Ulbricht) 2. Concept Campus - Bayreuth Synthesis of a suitable AB diblock and ABC triblock copos (Schacher/Müller) Thin block copo films phase diagrams orientation in thin films (Sperschneider/Krausch) Preparation and characterisation of composite membranes special characterisation by single molecule spectroscopy (to be announced/k /Köhler)

6 Fundamentals Sara, M. and Sleytr,, U.B. in 1987: Proteins of cell walls from bacteria -S-layer ultrafiltration membranes (Bacillus stearothermophilus)

7 deposition on commercially available microfiltration membranes Sara, M. and Sleytr,, U.B. in 1987

8 Rejection Curve of S-Layer Ultrafiltration Membranes made of S-Layer Matreial from Bacillus Stearothermophilus Sara, M. and Sleytr,, U.B. in 1987

9 The charachteristics of the thin film: cylindrical microdomains perpendicular with respect to the plane of the film Selective removal of the minority component yields a nanoporous membrane Switching the size of the residual minority component selectively allows to control the diameter of the pores Using ABC triblock-coplymers allows the preparation of core/shell cylinder structures

10 Procedure to create a composite membrane Preparation of oriented block copolymer film on a wafer by spin-coating methods Separation of the film from the wafer (e.g.:.: salt wafer separation with water) Deposition of the film on the support membrane Porous composite membrane Fixing the film on the support Analysing the composite structure via gas permeation removal of the pore template component / phase

11 Procedure to create a composite membrane Preparation of oriented block copolymer film direktly on the support membrane Porous composite membrane Analysing the composite structure via gas permeation removal of the pore template component/ phase

12 Campus Essen: 1. Characterisation of support membranes

13 SEM of oxyphen PET track-etched membrane with 30 nm nominal pore diameter

14 The diffusion measurement Membrane Feed Permeate

15 Lable dye flourescein isothiocyanat for dextran diffusion (FITC) O C N O O HO O OH

16 ε ε Δ Δ Δ = = Δ Δ = Δ = Δ = A c t d n D A A A t n J d t J D d c D J eff eff eff law) (1.fick [ ] [] [] index porosity membranearea[m ] s t t [m] themembrane thicknessof mol - m coefficent effectivdiffusion 2. 1 n.) (.) ( (feed) t (feed) t n n = = = Δ = Δ = = = Δ = Δ Δ Δ = ε ε A L mol c c c t d n n n n n s D A c t d n D n n n n perm t feed t n perm t perm t eff eff

17 results of the diffusion measurement (FITC labeled dextrane 4 kda) Test solution: : FITC labeled dextran mixture (5 kda), Concentration: : 25 μmol/l Used Membrane: RoTrac capillary pore membranes, PET, Porediameter 0.03 μm by Oxiphen GmbH

18 results of the diffusion measurement (FITC labeled dextrane 4 kda) increase of permeatconcentration concentration [µmol/l] 2,5 2 1,5 1 0,5 0-0, time [h]

19 results of the diffusion measurement (FITC labeled dextrane 4 kda) diffusion coefficent [m 2 /s] three measurements 1,6E-12 1,4E-12 1,2E-12 1E-12 8E-13 6E-13 4E-13 2E measurement No.

20 Diffusion measurement with dextran mixture

21 Results of the Diffusioncoefficient measurement via dextran mixture Signal Intensity [V] 0,025 0,020 0,015 0,010 0,005 Feedside Cell 2 startsolution feed 0 h after 2 h after 48 h after 96 h after 144 h after 192 h after 264 h after 360 h after 624 h Signal Intensity [V] 0,020 0,018 0,016 0,014 0,012 0,010 0,008 0,006 0,004 Permeatside Cell 2 Feed after 624 h after 360 h after 264 h after 192 h after 144 h after 96 h after 72 h after 24 h after 7 h after 4 h after 2 h 0, Elution Volume [ml] 0,002 0, Elution Volume [ml]

22 decrease of molar concentration w ith time feedside increase of molar concentration w ith time permeatside concentration [mol/l] 4,00E-05 3,00E-05 2,00E-05 1,00E-05 0,00E concentration [mol/l] 1,50E-05 1,00E-05 5,00E-06 0,00E time [h] time [h]

23 Feedside Δt [h] D eff [m 2 /s] average 2 1,28346E-11 5,17351E ,01238E ,55403E ,69416E ,72917E ,80045E ,11588E ,51733E ,53453E ,31129E-13 Permeatside Δt [h] D eff [m 2 /s] average 2 8,8042E-12 3,30901E ,2379E ,1008E ,787E ,3082E ,4547E ,4171E ,4699E ,5464E ,4964E ,8932E ,2446E-13

24 diffusion measurements with FITC labeled dextran diffusion coefficent [m 2 /s] 1,6E-12 1,4E-12 1,2E-12 1E-12 8E-13 6E-13 4E-13 2E measurement No.

25 Permporometry measurements Oxyphen PET track-etched membrane - nominal pore diameter 30 nm

26 Permporometry measurements Oxyphen PET track-etched membrane - nominal pore diameter 30 nm Oxiphen PET membrane porediameter 30 nm Permporometriedata 0,6 0,5 0,4 0,3 0,2 0,1 0 reativ occurence [%] 0,1446 0,1223 0,0867 0,0578 0,0434 0,0394 0,0358 0,0336 0,0320 0,0303 0,0290 0,0278 0,0267 0,0256 0,0247 0,0238 0,0230 0,0222 0,0216 0,0209 0,0203 0,0197 0,0192 porediameter [μm]

27 dry flow vs. Pressure Flow (L/min) Pressure (bar)

28 2. Establishing and Characterizing of thin block- terpolymerfilms B x V y T z Actually used terpolymer: (polybutadiene-b-poly(2-vinyl pyridine)-b-poly(tert-butyl methacrylate) x Ph y Ph N O H z O

29 The wafer and the Film 24 mm

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31 rotation speeds vs. film thickness film thickness [nm ] rotation speed [rpm]

32 Further work 1 characterization of the membrane - Improvement of existing methods diffusion, permporometry - Diffusion measurements with different dextrans and their mixtures - Evaluation of base membranes: track-etched PET - 20 to 100 nm pore diameter Anopore membrane 20 nm UF membranes

33 Further work 2 - thinfilm and composite membrane - Creation of thin films of block copolymers - Atomic Force Microscopy (AFM) of block copo films - Preparation of block copolymer composite membranes - Analyzing the new composite membrane

34 Acknowledgements Prof. Ulbricht for allocation of the subject The financial support by the Volkswagen Stiftung via grant I/80865 is gratefully acknowledged.

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