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Extracting information on the surface monomer unit distribution of PLGA by ToF-SIMS.

Ogaki, R*; Shard, A G; Li, S M*; Vert, M*; Luk, S*; Alexander, M R*; Gilmore, I S; Davies, M C* (2008) Extracting information on the surface monomer unit distribution of PLGA by ToF-SIMS. Surf. Interface Anal., 40 (8). pp. 1168-1175.

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Abstract

The surface chemistries of a range of random poly l-lactide¿co-glycolide (PLGA) materials have been investigated using X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS) and gentle secondary ion mass spectrometry (G-SIMS). The estimated mole fraction of lactide units provided by SSIMS was in good agreement with bulk composition and not affected by contamination. Conversely, XPS assessment of lactide compositions was unreliable due to hydrocarbon contamination contributions. We also propose a novel model here to show that by using SSIMS, it was possible to determine infer the degree of trans-esterification for PLGA co-polymers synthesised from a mixture of lactide and glycolide homo-dimers. This was determined by introducing two independent parameters, the ratio of trans-esterified bonds to the total number of ester bonds, PT, and the lactide composition. The model has indicated that for this set of polymers, PT was approximately 25%. Furthermore, we demonstrated that G-SIMS successfully identified the structurally important key fragments leading to direct identification. Analysis by G-SIMS showed that the glycolic acid units from all PLGA compositions are emitted in a lower energy fragmentation process than lactic acid units.

Item Type: Article
Keywords: X-ray Photoelectron Spectroscopy, SSIMS, G-SIMS, PLGA, co-polymer
Subjects: Nanoscience
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4224

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