Paper AS-TuM12
Surface Domain Analysis of a Blended Polymer System Using ToF-SIMS

Tuesday, October 21, 2008, 11:40 am, Room 207

Biodegradable polymers can serve as drug delivery platforms, thus, understanding the dynamic environment that occurs during degradation, in addition to the static surface chemistry, is crucial to developing better materials.¹ A desirable characteristic of biodegradable polymer materials is the potential for controllable degradation.²To that end, this research utilizes time-of-flight secondary ion mass spectrometry to evaluate lateral phase segregation at the surface of a polymer blend. The polymer blend consists of poly(L)lactic acid (PLLA) blended with a fluorine end-capped PLLA (FPLLA) with the expectation that domains of fluorine would appear at the surface. It is anticipated that by controlling domain size, degradation rates within and at the interface of domains can then be spatially tailored. The instrument used in this work is an ION TOF 5.100 equipped with a Bi_n⁺, Cs⁺, and C₆₀⁺ ion source. The spectra obtained from PLLA/FPLLA polymer blends showed the formation of cluster secondary ion repeating patterns in the region from approximately 900 Da to 2100 Da. Results from pure PLLA do not exhibit such cluster ion formation. Images of surface domain formation can be obtained from spatial analysis of the cluster ions from FPLLA even at very low FPLLA blend concentrations (ca. 1% ). Domain sizes at the surface range from 50 to 150 µm diameter. Depth profiles show the results of surface segregation of the end groups and connect to domains within the bulk of the blend.

¹ Ha, C.-S.; Gardella, J. A., Jr., Surface Chemistry of Biodegradable Polymers for Drug Delivery Systems. Chemical Reviews (Washington, DC, United States) 2005, 105, (11), 4205-4232.
² Peppas, N. A.; Langer, R., New challenges in biomaterials. Science FIELD Full Journal Title:Science (New York, N.Y.) 1994, 263, (5154), 1715-20.