1. Selective Surface Modification of Biopolymers REU Progress Presentation Presented by Alicia Certain Advisor Jeffrey Youngblood August 4, 2004

2. Polymers vs. Biopolymers  Familiar examples: garbage bags, milk jugs, car bumpers, motor oil, carpet fibers, plumbing pipes  Biopolymers: The “green” materials  Made from renewable resources  Biodegradable  Have different properties than traditional polymers

3. Wettability and Applications  An increase in wettability would be desirable for applications such as textiles, cleaning wipes, household fabrics  A decrease in wettability would be desired for packaging

4. The First Biopolymer  Family of polyhydroxyalkanoates (PHAs)  Worked with poly(lactic acid) (PLA)  Trade name “Natureworks”  Produced from corn

5. The Next Polymer  From the family of 1,3, propanediol  Specific polymer is poly(propylene- terephthalate) (PPT)  Trade name “Sorona”  Also comes from corn

6. Modification of Biopolymers  Samples were spin coated onto glass slides  Goal was to modify the surface of the polymers in order to change wettability  Worked with three chemical modifications  APTES  Hydrolysis  Aminolysis

7. APTES modification  3- aminopropyltriethoxysilane  Previously used to modify PET  Increased wettability  What will it do to biopolymers?

8. Hydrolysis  Immersion in aqueous alkaline base  Breaks up chain, adding hydroxyl group to one end, hydrogen to the other  Should increase wettability  Simplest procedure

9. Aminolysis  Similar to hydrolysis, using an amine instead  Tried n-butylamine, which is known to increase wettability in PET – very slow!  Used n-lithiodiamine to decrease reaction times

10. Contact Angle Analysis  Liquid drop on solid surface modifies its shape based on the interfacial tensions  Creates a material property of the system called the “contact angle”

11. Characterization  Contact angle measurements primary characterization  Tests done through the goniometer  AFM imaging used to augment

12. Wettability Results

13. Untreated PLA

14. 2 minutes

15. 15 minutes

16. Optimal Times

17. Wettability Results

18. Contact Angles 15 minutes 30 minutes 45 minutes

19. Wettability Results

21. PPT and APTES  Most successful in decreasing wettability  6 hours led to approx. 55 degree advancing, 0 receding  24 hours led to approx. 45 degree advancing, 0 receding  72 hours created an increase back to approx. 60 advancing, 0 receding

22. Flourinated APTES  24 hour APTES reaction on PLA with concentration cut in half  Subsequent reaction with tridecaflouro-1,1,2,2- tetrahydrooctyltri- chlorosilane  APTES on PLA only increases wettability slightly, but surface is functionalized and flourination successfully decreases wettability

23. Possible Future Directions  APTES optimization  Pinpointing a more definite optimum PLA hydrolysis time  Vapor phase reactions  Subsequent reactions on functionalized surfaces to increase hydrophobicity rather than decrease

24. Thanks! Prof. Youngblood and Prof. Kvam John, Ben, and Phil Allen and Kendra The REU Group