Selective Surface Modification of Biopolymers

Selective Surface Modification of Biopolymers

Selective Surface Modification of Biopolymers REU Progress Presentation Presented by Alicia Certain Advisor Jeffrey Youngblood August 4, 2004 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 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 The First Biopolymer

Family of polyhydroxyalkanoates (PHAs) Worked with poly(lactic acid) (PLA) Trade name Natureworks Produced from corn The Next Polymer From the family of 1,3, propanediol Specific polymer is poly(propyleneterephthalate) (PPT)

Trade name Sorona Also comes from corn 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

APTES modification 3aminopropyltriethoxysilane Previously used to modify PET Increased wettability What will it do to biopolymers? Hydrolysis Immersion in aqueous alkaline base Breaks up chain, adding hydroxyl group to one end, hydrogen to the other Should increase wettability Simplest procedure

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

Wettability Results (deg)) PLA Aminolysis 100 90 80 70 60 50 40 30

20 10 0 Advancing Receding 0 5 10 T im e (m in)

15 Untreated PLA 2 minutes 15 minutes Optimal Times PLA Aminolysis 100 90 80

(deg)) 70 60 50 Advancing Receding 40 30 20 10

0 0 1 2 3 Time (min) 4 5

Wettability Results PLA Hydrolysis 100 (deg)) 90 80 70 60 Advancing Receding

50 40 30 20 10 0 0 10 20 30

40 Time (min) 50 60 70 Contact Angles 30 minutes

15 minutes 45 minutes Wettability Results PPT Aminolysis 90 80 (deg)) 70 60

50 Advancing Receding 40 30 20 10 0 0 5

10 15 20 Time (min) 25 30 35

Wettability Results PPT Hydrolysis 90 80 (deg)) 70 60 50 Advancing Receding

40 30 20 10 0 0 20 40 60 80

Time (min) 100 120 140 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 Flourinated APTES 24 hour APTES reaction on PLA with concentration cut in half Subsequent reaction with tridecaflouro-1,1,2,2tetrahydrooctyltrichlorosilane APTES on PLA only increases wettability slightly, but surface is functionalized and flourination successfully

decreases wettability 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 Thanks! Prof. Youngblood and Prof. Kvam

John, Ben, and Phil Allen and Kendra The REU Group

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