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Influence of polydispersity of poly(lactic acid) on particle formation by rapid expansion of supercritical CO2 solutions.

TitleInfluence of polydispersity of poly(lactic acid) on particle formation by rapid expansion of supercritical CO2 solutions.
Publication TypeJournal Article
Year of Publication2010
Authors, , Acosta-Ramirez, A, Mehrkhodavandi, P, Signorell, R
JournalJournal of Supercritical Fluids
Volume51
Pagination376 - 383
Date Published2010///
ISBN Number0896-8446
Keywordspolydispersity polylactate particle expansion supercrit CO
Abstract

Poly(lactic acid) (PLA) particles were generated by rapid expansion of supercrit. PLA/CO2 solns. (RESS). Two different PLA samples, one with high (PDI = 2.4) and the other one with low (PDI = 1.4) polydispersity but similar no. av. mol. wt., were compared. After micronization, the polymers were analyzed by rapid-scan IR spectroscopy, SEM, size-exclusion chromatog., differential scanning calorimetry, and NMR spectroscopy. Our investigation reveals that the polydispersity of the polymers strongly affects the size but not the shape of the particles. We found larger particles (\~{}730 nm) for the PLA with high polydispersity than for the PLA with low polydispersity (\~{}270 nm). In both cases, spherical particles were formed. Moreover, our results clearly show that PLA with high polydispersity is less suitable for RESS processing because the low-mol. wt. chains are depleted over time and process conditions are thus not const. [on SciFinder(R)]