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Transport of Small Molecules in Polymers:

Overview of Research Activities

Benny D. Freeman Department of Chemical Engineering University of Texas at

Austin,

Office: CPE 3.404 and CEER 1.308B

Tel.: (512)232-2803, e-mail: freeman@che.utexas.edu

http://www.che.utexas.edu/graduate_research/freeman.htm

http://membrane.ces.utexas.edu

Develop fundamental structure/function rules

to guide the preparation of high performance

polymers or polymer-based materials for gas

and liquid separations as well as barrier

packaging applications.

Freeman Research Group Focus

• 15 Ph.D. students:

– Gas Separations: Qiang Liu, Kevin Stevens, Grant Offord, Tom Murphy, Katrina Czenkusch, David Sanders, Zach Smith*

– Liquid Separations: Wei Xie, Dan Miller*, Joe Cook, Geoff Geise, Michelle Oh, Albert Lee, Peach Kasemset*

– Barrier Materials: Kevin Tung

• 2 Postdocs: Dr. Claudio Ribeiro*, Dr. Chaoyi Ba

• Sponsors:

– NSF - 5 projects

– DOE – 2 projects

– Office of Naval Research - 1 project

– Industrial sponsors: PSTC, Air Liquide, Kuraray, Kraton

Polymers, ConocoPhillips, Statkraft, Dow Water Solutions

Freeman Research Group Profile

* = group members who have won major fellowships to support

their work from either the US govt. (NSF, DOE) or their home govt.

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Recent Graduates (within last 18 months)

Student Employer Area (Ph.D./Work)

Dr. Alyson Sagle Air Products, St. Louis, MO Fouling-resistant membranes/Gas

separation membranes

Dr. Yuan-Hsuan Wu Intel, Portland, OR Fouling-resistant

membranes/Microelectronics

Dr. Victor Kusuma Los Alamos (postdoc) Gas separation membranes

Dr. Lauren Greenlee NIST (postdoc), Boulder, CO High recovery desalination

membranes/Nanoparticles in water

treatment

Dr. Bryan McCloskey IBM (postdoc), San Jose, CA Fouling-resistant

membranes/Batteries

Dr. Hao Ju Dow, Midland, MI Fouling-resistant membranes/Battery

separators

Dr. Brandon Rowe NIST (postdoc), Gaithersburg, MD Physical aging in gas separation

membranes/Polymer physics of

membranes

Dr. Liz van Wagner GE Global Research, Niskayuna,

NY

Fouling-resistant

membranes/Membranes

Dr. Richard Li Advanced Hydro, Inc. Fouling-resistant membranes

• Gas Separations

• Thermally-Rearranged Polymers for Gas

Separation

• CO2/CH4 Separation for Natural Gas Purification

• Physical Aging in Glassy Polymers

• Physical Aging in Microlayered Polymers

• CO2/O2 Separation for Food Packaging

Applications

• Melt Processing Strategies to Prepare Thin

Membranes for Gas Separations

• Bioethanol Purification (Ethanol/Water Separation)

Current Projects - 1

• Liquid Separations

• Chlorine-Tolerant Desalination Membranes

• Desalination Membranes Based on Novel Block

Copolymers

• Fundamental Studies of Ion and Water Transport in

Polymers

• Melt Processing Strategies to Prepare Desalination

Membranes

• Bio-inspired Surface Modification of Water Purification

Membranes to Improve Fouling Resistance

Current Projects - 2

• Others

• Fundamental Studies of Oxygen Scavenging Polymers

for High Oxygen Barrier Packaging

• Hydrocarbon/Hydrocarbon Pervaporation for Refinery

Separations

Current Projects - 3

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0.01

0.1

1

10

100

0 5 10 15 20

Perm

eance [

L m

-2 h

-1 k

Pa

-1]

Time [h]

1 g/L BSA solution, pH=7.4

0.3 gpm crossflow, P=10.2 atm

0.2 m PVDF membrane

2000x

decrease

Internal fouling

Membrane

Feed flow

External fouling

Fouling: A Major Limitation in Liquid

Filtration Membranes

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HO

HO

NH2

N

OHHO

N

OHHO

N

HO OH

Dopamine Polydopamine

HO

HO

NH2

N

OHHO

N

OHHO

N

HO OH

Dopamine Polydopamine

H. Lee, S.M. Dellatore, W.M. Miller, and P.B. Messersmith., Mussel-Inspired

Surface Chemistry for Multifunctional Coatings. Science, 318, 426-430 (2007).

Mimicking Mussel Adhesion (“Bio-Glue”)

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Polydopamine

Polydopamine: Novel Fouling Resistant

Membrane Coating

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Michael Addition/ Schiff Base Reaction O

CH3H2Nn

Polydopamine

PEG ad-layer

Proposed Polydopamine Structure:

N

O

O

H

N

HN

O

H

PEG

Polydopamine as Surface “Primer” to Graft

PEG to Membrane Surfaces

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80

100

120

140

160

0 0.2 0.4 0.6 0.8 1

Flu

x [

Lm

-2h

-1]

Time [h]

Unmodified (85.4% rejection)

PTFE MFPDOPA-g-PEG modified

(94.5% rejection)

PDOPA modified

(95.7% rejection)

Conditions: P=0.3 atm, crossflow=120 L/h (Re=2500) 1500 ppm soybean oil/DC193-water emulsion (non-ionic)

Modification: 60 min PDOPA deposition time followed by 60 min 5KDa PEG-NH2 (1mg/mL, 60 °C)

Oily Water Filtration Using Pegylated Polydopamine

Treated Teflon Microfiltration Membranes

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- Two identical UF PAN membranes

that are highly hydrophilic

- One coated and one non-coated,

both processed high fouling water

stream from a bio-reactor with a lot

of sludge.

- 10 minute filtration followed by 1

min backwash cycle for 48+ hours.

- Both membranes were taken out

and flushed with a hose / water

- Modified membrane washes clean

- Non-modified retains sludge film

- Membrane housings (hydrophobic)

also showed significantly better

anti-stick, fouling resistant surface

Field Validation - Visual

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- Pressure increases during single filtration/back-flush cycle due to fouling

- Almost twice the volume of water could be processed for same end-point pressures

- Unmodified shows pressure increase at a rate of 1.55 psi/hr vs. 1.1 psi/hr for modified membrane

Unmodified

Modified

40% Lower Energy

2X More Water

Processed Between

Cleanings

Field Validataion: Ultrafiltration of Bioreactor

Effluent

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• 100 trillion scf of natural gas used worldwide per year

– All requires pretreatment

• Amine absorption is the leading technology

• Membranes have < 5% market share

R.W. Baker, K. Lokhandwala, Natural gas processing with membranes: An overview, Industrial & Engineering Chemistry Research. 47 (2008) 2109-2121.

Natural Gas Processing

Science, vol. 318, 12 October 2007, pp. 254-258.

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CO2/CH4 Separation Performance

1: PIOFG-1 2: TR-1-350 3: TR-1-400 4: TR-1-450 5-19: OTHER TR POLYMERS

N NCF3

CF3

O

OO

OOH OH

F3C CF

3

H.B. Park, C.H. Jung, Y.M. Lee, A.J. Hill, S.J. Pas, S.T. Mudie, E. van Wagner, B.D.

Freeman, & D.J. Cookson, Polymers with Cavities Tuned for Fast, Selective

Transport of Small Molecules and Ions, Science, 318, 254-258 (2007).

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2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0

(d)

(c)

(b)

R

ela

tive in

ten

sit

y (

a.u

.)

Cavity radius (A)

(a)

o

Cavity Size Distribution from Positron

Annihilation Lifetime Spectroscopy

(a) PIOFG-1

(b) TR-1-350

(c) TR-1-400

(d) TR-1-450

N NCF3

CF3

O

OO

OOH OH

F3C CF

3

Lin et al., Science, 311, pp. 639-642 (2006).

Beating the Permeability-Selectivity Tradeoff

for H2 Purification

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Reduction to Practice

CO2 Selective Materials

Using Nanocomposites to Enhance Membrane Separations

Using Nanolayering to Enhance Gas Barrier Properties