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ResearchPresentation
- 1. ME 4474: Independent Study : Anti-Fouling Polymer Surface via Micro-Patterned Optimization Samuel Gates, Undergraduate Researcher Dr. Carl Frick, PI Dr. Jonathan Brant, co-PI Chris Laursen, M.S. Candidate
- 2. • Growing interest in membrane filtration of industry produced water • Membrane fouling is of major concern in desalinization of brackish water • Specific aim of research –Synthesize micro-patterned surface utilizing polymer system capable of switchable ductility
- 3. Motivation of Filtration Surface Room temp. water Rigid structure Porous membrane Warm backwash water Flexible structure • Stiff during operation and flexible during backwash • Antifouling characteristics – Steric repulsion – Decrease contact area • Assists particle removal
- 4. Lightly Crosslinked Polymer System 38.20°C 51.07°C 0.0 0.5 1.0 1.5 2.0 2.5 3.0 TanDelta 0.1 1 10 100 1000 10000 StorageModulus(MPa) 0 20 40 60 80 100 120 Temperature (°C) Sample: Dry 90/10 5%P550 Sample 2 Size: 18.0193 x 6.7200 x 1.0900 mm Method: LaursenTempSweep DMA File: C:...5% PEGDMA550D90_10_5P550.003 Operator: Chris Laursen Run Date: 31-Oct-13 08:27 Instrument: DMA Q800 V20.9 Build 27 Universal V3.9A TA Instruments Stiff Ductile Tonset
- 5. Desired Material Parameters • Stiff during operation – Onset temperature 30-40oC under submerged conditions • Flexible during backwashing – Short transition range • Partially hydrophilic to assist anti-fouling • Ability to be photopolymerized into structured surface
- 6. • Test various polymers for glass transition and percent water absorption –5 monofunctional (linear) –4 multifunctional (Crosslinked) • Determine appropriate polymer system constituents • Mechanically test polymer system
- 7. • tert-Butyl acrylate (tBA) • 2-Hydroxyethyl methacrylate (2HEMA) • 2-Ethoxyethyl methacrylate (2EEM) • Poly(propylene glycol) acrylate (PPGA) • 2-Carboxyethyl acrylate (2CEA) • Di(ethylene glycol) dimethacrylate (DEGDMA) • Poly(ethylene glycol) dimethacrylate Mn 550 (PEGDMA550) • Poly(ethylene glycol) dimethacrylate Mn 750 (PEGDMA750) • Dipentaerythritol penta/hexaacrylate (DPPHA) Polymer Constituents
- 8. Sample Fabrication • Mixing – 0.5% Photo initiator • Teflon Molds • UV lamp – 30 minutes • Oven – 60 minutes • Sample preparation
- 9. Dynamic Mechanical Analysis • 1cm x 6cm x 0.1cm samples • Measures – Storage Modulus – Loss Modulus • Used to determine – Glass transition temperature – Onset temperature
- 10. Dynamic Mechanical Analysis 38.20°C 51.07°C 0.0 0.5 1.0 1.5 2.0 2.5 3.0 TanDelta 0.1 1 10 100 1000 10000 StorageModulus(MPa) 0 20 40 60 80 100 120 Temperature (°C) Sample: Dry 90/10 5%P550 Sample 2 Size: 18.0193 x 6.7200 x 1.0900 mm Method: LaursenTempSweep DMA File: C:...5% PEGDMA550D90_10_5P550.003 Operator: Chris Laursen Run Date: 31-Oct-13 08:27 Instrument: DMA Q800 V20.9 Build 27 Universal V3.9A TA Instruments Tg
- 11. DMA Results Linear polymers Crosslinking polymers
- 12. Water Absorption Methods • Soak samples in double distilled water • Place in incubator – 37°C – 30 RPM • Measured mass before and after soaking
- 14. Ternary Polymer System • Linear building constituents: tBA and 2HEMA • Crosslinker: PEGDMA550
- 15. • 94.5 wt.% 9:1 tBA-co- 2HEMA • 5 wt.% PEGDMA550 • 0.5 wt.% photo-initiator • Tonset = 32°C • Tg = 51°C • Water absorption of 1.44±0.18% within 12 Hrs
- 16. • Further mechanical testing • Optimize micro-patterned surface – Pillar size, aspect ratio, and patterning • Qualitative assessment of anti-fouling properties of shape memory polymer structures
- 17. • Tested a variety of acrylate macromolecules for base properties • Produced a ternary polymer network optimized for our system – Good shape memory properties – Reached targeted onset temperature – Photo-curable • Optimize pillared surfaces • Test application effectiveness
Editor's Notes
- Dave
- Due the dwindling amount of fresh-water supplies. Utilization of porous membranes as a filtration device is a growing area of interest. Thus anti-fouling surface treatments are quite necessary.
- Basic premise: Fabricate micro-patterned pillars that are stiff during operation and flexible during backwash These pillars will inhibit large enough particles from even reaching the membrane filter and will hinder the contact area made by smaller particles and the membrane. The latter characteristic is based on reducing the amount Van Der Waal’s forces. Flexible pillars will facilitate the removal of foulants that may accumulate.
- Characteristic of polymers is that they are stiff in relatively low temps…….. Won’t discuss graph
- Stiff while filtering room ambient temperature water Ideally have short transition to have an attainable glassy regime
- Test 5 linear and 4 crosslinked Use this data to determine an appropriate polymer system Test mechanically—which we all had the pleasure be apart of for our last lab in this class
- Teflon Molds used for DMA samples and load frame samples Oven at 90 C Samples would often need sanding on edges using a rotary polish or sandpaper
- Measure Storage modulus and loss modulus over a specified temperature range Using these two values a phase difference can be determined which then leads us to the glass transition temperature
- This is the storage modulus and the tangent of the phase angle
- Confusing plot -Shows transition of each of the linear polymer and crosslinked polymers -What is special about this graph….is it help predict transition temperatures of polymer mixtures Here is a projection of a tBA and DEGDMA mixture. -Important to note area of interest. -Less than 20% in order to even have a transition -Need to have a suitable transition. Temperature.
- In order to test the %water absorption samples were placed in vials filled with water and placed in an incubator over a specific period of time. Masses were taken at different times.
- tBA reliable mechanical behaviors and fabrication 2HEMA water absorption PEGDMA550 partial stiffness and water absorption Tailor amount of 2HEMA to have a suitable transition
- Mechanical testing to solidify our understanding of the material’s properties Optimize the patterned surface- which is most effect for anti-fouling assess the polymer’s surface energies which can indicate fouling likely hood
- Dave