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https://hdl.handle.net/1822/30945
Título: | Confinement effects on the dynamic behavior of poly(d,l‑lactic acid) upon incorporation in α‑cyclodextrin |
Autor(es): | Viciosa, M. T. Alves, N. M. Oliveira, T. Dionísio, M. Mano, J. F. |
Palavras-chave: | Inclusion complexes PDLLA |
Data: | Set-2014 |
Editora: | ACS Publications |
Revista: | The Journal of Physical Chemistry |
Citação: | Viciosa M. T., Alves N. M., Oliveira T., Dionisio M., Mano J. F. Confinement Effects on the Dynamic Behavior of Poly(D,L‑lactic Acid) upon Incorporation in α‑Cyclodextrin, J Phys Chem B, Vol. 118, pp. 6972-6981, 2014 |
Resumo(s): | Inclusion complexes (ICs) composed of α-cyclodextrin (α-CD) and poly(D,L-lactic acid) (PDLLA), with 10/24 (IC1) and 15/46 (IC2) (% w/ w) of PDLLA incorporated/initial PDLLA weight percentage, were prepared and characterized mainly by dielectric relaxation spectroscopy (DRS). Bulk PDLLA was also analyzed for comparison. DRS was revealed to be a suitable tool to distinguish the dynamical response of the PDLLA regions constrained in between α-CD channels from the fraction incorporated inside channels. While the cooperative α-process undergoes a dramatic depletion shifting to higher temperatures (∼4.5 °C) for the PDLLA interchannels portion, it is suppressed for PDLLA chains inside pores. It was demonstrated that the broad secondary relaxation of bulk PDLLA is the Johari−Goldstein process (βJGprocess). The detection of its analogue in the ICs at higher frequencies, to a greater extent in IC1, is interpreted as a true confinement effect where the dimensions of the α-CD channels interfere with the length scale of the βJG-process. The limit predicted in the framework of the coupling model, where the α-relaxation transforms in the βJG-process, seems to be reached in the ICs. Furthermore, it was found that the length scale of the additional γ process only detected in the ICs is inferior to inter- or intrachannel dimensions. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/30945 |
DOI: | 10.1021/jp5045783 |
ISSN: | 1520-6106 |
Arbitragem científica: | yes |
Acesso: | Acesso restrito UMinho |
Aparece nas coleções: | 3B’s - Artigos em revistas/Papers in scientific journals |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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18141-JPhysChemB118_6072_14.pdf Acesso restrito! | 1,5 MB | Adobe PDF | Ver/Abrir |