Influence of residual monomers and metals on poly (l-lactide) thermal stability

Cam, Darinn; Marucci, Mariagrazia

doi:10.1016/s0032-3861(96)00711-2

Cited by 176 publications

(121 citation statements)

References 11 publications

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“…Interestingly, the presence of solvent does not affect the thermal stability of the PLLA since the onset (T o ) and end (T end ) degradation temperatures are similar to those observed for the PLLA pellet. This result is in accordance to other studies that determined that low molecular weight compounds such as residual solvents and moisture, can be removed without affecting the thermal stability of the material (Cam and Marucci, 1997;Lim et al, 2008).…”

Section: Resultssupporting

confidence: 92%

“…It has been demonstrated that residual metal catalysts (Sn, Fe, Zn, Al) and especially metal oxides/hydroxides (CaO, MgO, Mg(OH) 2 ) reduce the thermal stability of PLLA (Cam and Marucci, 1997;Fan et al, 2004;Nishida et al, 2005;Chiang et al, 2011). Relevant for this investigation is that chemical reactivity of pure Mg is much higher than MgO reactivity -Mg particles are highly flammable, can spontaneously ignite and react violently with oxidising agents-, which could additionally impose a serious technical limitation during processing.…”

Section: Introductionmentioning

confidence: 99%

“…Thermal stability of the PLLA during processing could also be altered by the presence of Mg particles, as observed for other metallic compounds of interest to control its depolymerization into L,L-lactide for feedstock recycling (Cam and Marucci, 1997;Nishida et al, 2005;Motoyama et al, 2007;Chiang et al, 2011). It has been demonstrated that residual metal catalysts (Sn, Fe, Zn, Al) and especially metal oxides/hydroxides (CaO, MgO, Mg(OH) 2 ) reduce the thermal stability of PLLA (Cam and Marucci, 1997;Fan et al, 2004;Nishida et al, 2005;Chiang et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Does magnesium compromise the high temperature processability of novel biodegradable and bioresorbables PLLA/Mg composites?

Cifuentes¹,

Benavente²,

González-Carrasco³

2014

REVMETAL

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This paper addresses the influence of magnesium on melting behaviour and thermal stability of novel bioresorbable PLLA/Mg composites as a way to investigate their processability by conventional techniques, which likely will require a melt process at high temperature to mould the material by using a compression, extrusion or injection stage. For this purpose, and to avoid any high temperature step before analysis, films of PLLA loaded with magnesium particles of different sizes and volume fraction were prepared by solvent casting. DSC, modulated DSC and thermogravimetry analysis demonstrate that although thermal stability of PLLA is reduced, the temperature window for processing the PLLA/Mg composites by conventional thermoplastic routes is wide enough. Moreover, magnesium particles do not alter the crystallization behaviour of the polymer from the melt, which allows further annealing treatments to optimize the crystallinity in terms of the required combination of mechanical properties and degradation rate. RESUMEN: ¿Compromete el magnesio la procesabilidad a elevada temperatura de nuevos materiales compuestos biodegradables y biorreabsorbibles de PLLA/Mg?.Este trabajo aborda la influencia de magnesio en el comportamiento a fusión y en la estabilidad térmica de nuevos compuestos de PLLA / Mg biorreabsorbibles como una forma de investigar su procesabilidad mediante técnicas convencionales, lo que probablemente requerirá una etapa en estado fundido a alta temperatura para moldear el material mediante el uso de una etapa de compresión, extrusión o inyección. Para este fin, los materiales de PLLA cargados con partículas de magnesio, de diferentes tamaños y fracción de volumen, se prepararon por la técnica de disolución y colada, evitando así el procesado a alta temperatura antes del análisis. El análisis mediante DSC, DSC modulada y termogravimetría demuestra que, aunque la estabilidad térmica de PLLA se reduce, el intervalo de temperatura para su procesado por rutas convencionales es suficientemente amplio. Además, las partículas de magnesio no alteran la cristalización del polímero a partir del fundido, lo que permitirá optimizar el grado de cristalinidad mediante tratamientos posteriores de recocido y conseguir así una adecuada combinación de propiedades mecánicas y velocidad de degradación.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Does magnesium compromise the high temperature processability of novel biodegradable and bioresorbables PLLA/Mg composites?

Cifuentes¹,

Benavente²,

González-Carrasco³

2014

REVMETAL

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“…Indeed, AFM analysis of the pSi-PLLA (spin-coated) ( Figure 8B) shows that the pores have been totally occluded by polymer, in contrast to the pSi-Ox ( Figure 5B) and to pSi-PLLA (grafted) [38]. Due to solubility issues, the molecular weight of PLLA used for the spin coating and monolith production was determined from TGA measurements by using the published relationship between decomposition temperature and molecular weight [73].…”

Section: Resultsmentioning

confidence: 99%

Controlled Drug Delivery From Composites of Nanostructured Porous Silicon and Poly( L -Lactide)

et al. 2012

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Aims: Porous silicon (pSi) and poly(L-lactide) (PLLA) both display good biocompatibility and tunable degradation behavior, suggesting that composites of both materials are suitable candidates as biomaterials for localized drug delivery into the human body. The combination of a pliable and soft polymeric material with a hard inorganic porous material of high drug loading capacity may engender improved control over degradation and drug release profiles and be beneficial for the preparation of advanced drug delivery devices and biodegradable implants or scaffolds. Materials & methods: In this work, three different pSi and PLLA composite formats were prepared. The first format involved grafting PLLA from pSi films via surface-initiated ring-opening polymerization (pSi–PLLA [grafted]). The second format involved spin coating a PLLA solution onto oxidized pSi films (pSi–PLLA [spin-coated]) and the third format consisted of a melt-cast PLLA monolith containing dispersed pSi microparticles (pSi–PLLA [monoliths]). The surface characterization of these composites was performed via infrared spectroscopy, scanning electron microscopy, atomic force microscopy and water contact angle measurements. The composite materials were loaded with a model cytotoxic drug, camptothecin (CPT). Drug release from the composites was monitored via fluorimetry and the release profiles of CPT showed distinct characteristics for each of the composites studied. Results: In some cases, controlled CPT release was observed for more than 5 days. The PLLA spin coat on pSi and the PLLA monolith containing pSi microparticles both released a CPT payload in accordance with the Higuchi and Ritger–Peppas release models. Composite materials were also brought into contact with human lens epithelial cells to determine the extent of cytotoxicity. Conclusion: We observed that all the CPT containing materials were highly efficient at releasing bioactive CPT, based on the cytotoxicity data. Original submitted 16 December 2010; Revised submitted 29 September 2011; Published online 6 March 2012

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“…(268 °C and 88.3% weight loss in bulk form). TGA was also nm on a solution polymerised (48 hrs, 10 J.lmol, Sn(Octh and 10 mmol of L-lactide without pSi) sample ofPLLA that was found to decompose at 282 °C (94.7% weight loss), in comparison the decomposition temperature of PLLA at infinite molecular weight is 353 °C [31]. The lower decomposition temperatures indicate that the three standard samples possess low molecular weight PLLA [25].…”

Section: Atomic Force Microscopy (Afm) Of Psi-plla Filmsmentioning

confidence: 99%

Characterisation of porous silicon/poly( L -lactide) composites prepared using surface initiated ring opening polymerisation

et al. 2005

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Influence of residual monomers and metals on poly (l-lactide) thermal stability

Cited by 176 publications

References 11 publications

Does magnesium compromise the high temperature processability of novel biodegradable and bioresorbables PLLA/Mg composites?

Does magnesium compromise the high temperature processability of novel biodegradable and bioresorbables PLLA/Mg composites?

Controlled Drug Delivery From Composites of Nanostructured Porous Silicon and Poly( L -Lactide)

Characterisation of porous silicon/poly( L -lactide) composites prepared using surface initiated ring opening polymerisation

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