Tunable Nanoporous Membranes with Chemically Tailored Pore...
Transcript of Tunable Nanoporous Membranes with Chemically Tailored Pore...
Tunable Nanoporous Membranes with Chemically Tailored Pore Walls from Triblock Terpolymer Templates
Presented by Jacob L. Weidman1 With research from Ryan A. Mulvenna,2 John A. Pople,3
Bryan W. Boudouris,2 and William A. Phillip1 [email protected]
1University of Notre Dame, 2Purdue University, 3Stanford Synchrotron Radiation Lightsource
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Filtration is Size-Selective 2
A New Membrane Material
• High flux • Good selectivity • Mechanical integrity • Low fouling
Phase inversion
Desired qualities for ultrafiltration membranes:
Self-assembled Track-etched
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Block Copolymers Self-Assemble
Q230 H Q229 fRed
Cochran, E. W. et al. Macromolecules 2006, 39, 2449.
N = number of segments χ = interaction parameter f = polymer volume fraction
L Q230 H Q229 fRed
Red Polymer MINORITY PHASE
Red Polymer MAJORITY PHASE
Theoretical Coil-Coil Diblock Copolymer Phase Diagram
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Membrane Cast by SNIPS
Solvent
Solvent Non-solvent Selective Layer
Support Layer
Evaporate
Precipitate Membrane
Doctor Blade
Polymer Solution
Cast
Glass Slide
Water bath Self-assembly
SNIPS- Self-assembly and Non-solvent Induced Phase Separation
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Prior Efforts Limited by Functionality
Block Function Polyisoprene Increases toughness Polystyrene Forms matrix
Poly(4-vinyl pyridine) pH-responsive, but terminal chemistry
Cast Membrane
Phillip, W. A. et. al. Nano Letters, 2011, 11, 2892-2900.
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Pore Walls Can be Functionalized
Cast Membrane
Block Function Polyisoprene Decreases brittleness Polystyrene Forms matrix
Poly(Dimethylacrylamide) Can be functionalized to specific applications
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Triblock Polymerization by RAFT
Tolerant of atmospheric conditions
Low dispersity
Metal-free
1.3 1.3 1.2
RAFT- Reversible Addition-Fragmentation chain Transfer
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Asymmetric Membrane Produced 9
A Permeable and Selective Membrane 10
Membrane Functionalization
Solvent
Solvent Non-solvent
Evaporate
Precipitate
Doctor Blade
Polymer Solution
Cast
Glass Slide
Water bath
6M HCl in Water
Heat to 85ºC React for 2 days
Functionalization
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Functionalization Alters Pore Chemistry
Pore walls can be reacted to a variety of functional groups (pink dots).
“Click” Chemistry
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Porous Structure Retained Parent Functionalized
Less than 4% deviation in average pore size and porosity
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A Selective pH-responsive Membrane 14
Parent Functionalized
Parent Functionalized Parent
How Pore Wall Groups Affect Pore Size
Dry state (SEM) PDMA Wet State (MWCO) Parent Membrane
Average- 52 nm Water soluble Estimated- 8.1 nm
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Parent Functionalized
Parent
• AFM to compare wet/dry pore sizes • New functional to line pore walls • Transport tests for targeted applications
Functionalized Estimated -2.6 nm
Conclusions
This material produces robust selective membranes with a high density of monodisperse pores in the self-assembled selective layer.
Pore walls have been successfully deprotected to a functionalizable polyacrylic acid group, lending itself to a variety of applications by simple chemical conversion.
Controlled radical polymerization allows for a scalable production method of terpolymer with tunable block lengths and low dispersity. I D
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Acknowledgements
As well as:
– Center for Environmental Science and Technology (CEST)
– Notre Dame Integrated Imaging Facility (NDIIF)
THANK YOU!!
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Special thanks to: Professor Bryan W. Boudouris Ryan A. Mulvenna
Professor William A. Phillip John Pople