Advances in Polymer-based Barrier Materials for Packaging Applications

1. Transport of Small Molecules in Polymers: Overview of Research Activities Benny D. Freeman Department of Chemical Engineering University of Texas at Austin, Office: CPE 3.466 Tel.: (512)232-2803, e-mail: freeman@che.utexas.edu http://www.che.utexas.edu/graduate_research/freeman.htm http://membrane.ces.utexas.edu March 2004

2. Focus Develop fundamental structure/function rules to guide the preparation of novel, high performance polymers or polymer-based materials for gas and liquid separations as well as barrier packaging applications.

3. Current Group/Program Profile • 11 Ph.D. students: • Gas Separations: Scott Matteucci, Roy Raharjo, Scott Kelman, Rajeev Prabhakar, Haiqing Lin • Liquid Separations: Conor Braman, Alyson Sagle, Bryan McCloskey, Hao Ju, Yuan-Hsuan Wu • Barrier Materials: Keith Ashcraft • Administrative assistant: Sande Storey • Sponsors: • NSF - 1 project • DOE - 3 projects • Office of Naval Research - 4 projects • Industrial sponsors: Pall Corp., Air Liquide, Eastman Chemical

4. Reactive Oxygen Barrier Materials • Growing demand for packaging oxygen sensitive products in flexible, polymer-based containers (food & beverage packaging, microelectronic components, pharmaceutical agents, etc.) • Most polymer packaging does not have sufficient oxygen barrier to meet new applications. • Recent discoveries in industry have shown that adding certain salts to polymers can markedly increase the oxygen barrier properties, but there are no fundamental studies of the mechanism, kinetics, etc. of these systems to serve as a basis for optimization.

5. Example of Oxygen Scavenging with Cobalt Salt in MXD6 Nylon PET = poly(ethylene terephthalate), one of the most widely used packaging materials known.

6. Filled Polymer Membranes: Background Nonporous, impermeable filler Data of Barrer et al., Journal of Polymer Science, 1, 2565-2586 (1963).

7. Effect of Silica Nanoparticles on PMP Permeability and Mixed-Gas Selectivity s: Barrer et al., Journal of Polymer Science, 1, 1963 : Most, Journal of Applied Polymer Science, 14, 1970 2 % n-butane / 98% methane feed; upstream pressure = 150 psig; downstream pressure = 0 psig Merkel et al., Ultrapermeable, Reverse-Selective Nanocomposite Membranes, Science, 296, 519-522 (2002).

8. Problem with Conventional Membranes: Fouling Organic rejection (i.e., oil + surfactant) is >95%.

9. Nonporous Pebax 4011 Coating on Porous PVDF Nonporous Pebax 4011 coating Microporous PVDF support Pebax 4011: 57 wt% PEG, 43 wt. % PA6:

10. Fouling Properties of Pebax 4011 Coated Membrane and Conventional Porous Membrane Pebax 4011: 57 wt% PEG, 43 wt. % PA6:

11. Separation Properties of Pebax 1074/PDVF Composite Spiral Wound Membrane Modules 10,000 ppm motor oil/1000 ppm surfactant in water 1,000 ppm motor oil + surfactant in water (90% rejection) 100 ppm motor oil + surfactant in water (99% rejection) Membrane Area: 1 m2

12. Attachment Chemistries Enzymes were immobilized onto the membranes using many different surface activation strategies • Chitosan • Direct attachment • Bis(sulfosuccinimdyl) suberate • Glutaraldehyde • Hydroxyethyl Cellulose • Direct attachment • 4-nitrophenyl chloroformate

13. Enzyme Coupling to Chitosan Membranes • Coupling of Enzymes Chitosan-N=CH-(CH2)3-CHO +  Chitosan-N=CH-(CH2)3-CH=N-Enzyme H2N-(CH2)4- H2N-(CH2)4- a-chymotrypsin

14. Initial Memzyme Fouling Results • Membranes exposed to 1% BSA at for 23 days and at 3% for 2 days in a continuous loop permeation system. • Porous PVDF membrane exhibits obvious surface fouling; the other samples do not. • BSA rejection for all samples was approx. 99%.