Síntese e caracterização térmica e química do copolímero poli(D,L-lactídeo-co-glicolídeo)

Erbetta, Cynthia D’Avila Carvalho; Viegas, Carla C. B.; Freitas, Roberto F. S.; Sousa, Ricardo Geraldo de

doi:10.1590/s0104-14282011005000063

Cited by 13 publications

(7 citation statements)

References 14 publications

(18 reference statements)

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“…PLGA-R presents only Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres one step of weight loss between 170 °C and 370 °C and T max (maximum rate of decomposition temperature) near to 275 °C. This behavior is in agreement with the literature 27,28 . The degradation products of PLGA are similar to those of the neat poly(lactide) (PLA) and poly(glycolide) (PGA) polymers.…”

Section: Resultssupporting

confidence: 94%

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

et al. 2015

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Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (E α ) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.

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Section: Resultssupporting

confidence: 94%

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

et al. 2015

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“…S2b). The T g values for PLGA and s‐OLGAs decrease from 38°C for PLGA to 22°C for s‐OLGA‐2500 and are in good agreement with literature . A decreasing molecular weight leads to a lower glass transition temperature for the hydrolyzed OLGA fragments caused by a high amount of functional end‐groups, which have a higher mobility and a plasticizing effect .…”

Section: Resultssupporting

confidence: 87%

Influence of intermediate degradation products on the hydrolytic degradation of poly[(rac‐lactide)‐co‐glycolide] at the air–water interface

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Falkenhagen

Travkova

et al. 2015

Polymers for Advanced Techs

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The influence of intermediate degradation products on the hydrolytic degradation of poly[(rac-lactide)-co-glycolide] (PLGA, 50 mol% lactide) at the air-water interface is investigated using the Langmuir film balance. For that purpose, PLGA bulk samples were degraded in aqueous solution for different time periods to generate different sized fragments with varying water solubility. After dissolution in chloroform the water-insoluble degradation products are able to form Langmuir monolayers with an increased elasticity modulus by decreasing molecular weights. Watersoluble degradation products of PLGA were found to be surface active and form an adsorption layer at the airwater interface, which can be further compressed, and revealing a different adsorption behavior in dependence on their composition. The obtained results imply that measured surface area reduction as it is determined in Langmuir monolayer degradation (LMD) experiment is restricted by the effect of the surface activity of adsorbed oligomer fragments during the degradation process. The surface activity of the formed degradation products makes it difficult to derive degradation mechanism from a common LMD experiment. To elucidate the mechanism in detail, dimers, trimers and longer oligomers with known composition and end-groups have to be investigated. Copyright

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“…Observase uma banda entre 3400 e 3600 cm -1 no espectro mostrado na Figura 3, característica do grupo hidroxila, ausente nos espectros encontrados neste trabalho. Essa banda descrita na literatura, talvez pode ser devido à presença de umidade na amostra, de solvente residual, ou da absorção de (OH) do grupo carboxila resultante da hidrólise do monômero [34] .…”

Section: Desenvolvimento Da Metodologia Para Síntese Do Poli(ácido Láunclassified

Desenvolvimento da metodologia para síntese do poli(ácido lático-co-ácido glicólico) para utilização na produção de fontes radioativas

et al. 2015

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ResumoA Organização Mundial da Saúde (OMS) relata o câncer como uma das principais causas de morte no mundo. Uma modalidade de tratamento que vem sendo bastante utilizada no tratamento do câncer de próstata é a braquiterapia, que consiste na introdução de sementes com material radioativo no interior do orgão. Sementes de Iodo-125 podem ser inseridas soltas ou em cordas poliméricas fabricadas a partir do (poli(ácido lático-co-ácido glicólico)) (PLGA). Foi proposto neste trabalho, o estudo e desenvolvimento da metodologia de síntese do biopolímero PLGA. Os resultados obtidos demonstram que, através da metodologia utilizada, foi possível determinar os melhores parâmetros de reação (tempo e temperatura) para o PLGA na proporção 80/20 (lactídeo/glicolídeo). Com uma temperatura de 110 °C e tempo de reação 72h o rendimento da reação é superior a 90%. Os valores de massas moleculares obtidas entre os testes, ainda são baixos quando comparados com os valores obtidos por outros autores na literatura. Novos testes estão sendo conduzidos, utilizando dímeros preparados no laboratório. Testes substituindo o vácuo por uma atmosfera de nitrogênio também estão sendo realizados. Essas duas substituições podem aumentar o valor final da massa molecular do polímero. Em relação à caracterização, as técnicas utilizadas confirmaram a estrutura esperada do polímero. Palavras-chave: câncer de próstata, braquiterapia, poli(ácido lático-co-ácido glicólico), PLGA. AbstractAccording to the World Health Organization, cancer is a leading cause of death worldwide. A radiotherapy method extensively used in prostate cancer is brachytherapy, where the area requiring treatment receives radioactive seeds. Iodine-125 seeds can be inserted loose or stranded in bioabsorbable polymers produced from poly(lactic-co-glycolic acid) (PLGA). We developed the synthesis methodology for PLGA and the results obtained show that it was possible to determine the optimal reaction parameters (time and temperature) for PLGA in 80/20 (lactide/glycolide) ratio. The yield was higher than 90% using a temperature of 110 °C and reaction time of 72 hours; however, the molecular weight values obtained are very low compared to those obtained by other authors. New tests using previously synthesized dimers and nitrogen atmosphere are being performed. These conditions could potentially increase the molar mass of PLGA. All techniques used confirmed the expected structure of the polymer.

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Síntese e caracterização térmica e química do copolímero poli(D,L-lactídeo-co-glicolídeo)

Cited by 13 publications

References 14 publications

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

Influence of intermediate degradation products on the hydrolytic degradation of poly[(rac‐lactide)‐co‐glycolide] at the air–water interface

Desenvolvimento da metodologia para síntese do poli(ácido lático-co-ácido glicólico) para utilização na produção de fontes radioativas

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