Drying of PAAm hydrogels at various temperatures: A fluorescence study
Yükleniyor...
Dosyalar
Tarih
2007-05
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Taylor & Francis Group
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The steady-state fluorescence (SSF) technique was employed for studying the drying of polyacrylamide (PAAm) hydrogels. Disc-shaped hydrogels were prepared by free-radical crosslinking copolymerization of acrylamide (AAm) with N,N'-methylene bisacrylamide (BIS) as crosslinker in the presence of ammonium persulfate (APS) as an initiator. Pyranine (P) was introduced as a fluorescence probe and the intensity of pyranine was monitored during in situ drying at various temperatures. It was observed that the fluorescence intensity of pyranine increased during the drying process. A supporting, gravimetrical experiment was also performed. A phenomenological equation was introduced to determine the desorption coefficient, D, of water molecules from the drying hydrogels at various temperatures. The desorption activation energy, triangle E-d, values were measured for the drying processes and found to be 91.08 and 36.82 kJ mol(-1) by fluorescence and gravimetrical methods, respectively. This difference most probably originates from the origin of the techniques; the fluorescence technique measures the parameters at a molecular level, whereas the gravimetrical technique measures a parameter in the bulk.
Açıklama
Anahtar Kelimeler
Activation energy, Drying, Fluorescence, Hydrogels, Fast transient fluorescence, Gels, Heterogels, Diffusion, Behavior, Crosslinking, Desorption, Free radicals, Ammonium persulfate (APS), Pyranine, Steady-state fluorescence (SSF)
Kaynak
Journal of Macromolecular Science, Part B: Physics
WoS Q Değeri
Q4
Scopus Q Değeri
Q3
Cilt
46
Sayı
3
Künye
Aktaş, D., Pekcan, M. Ö. & Evingür, G. (2007). Drying of PAAm hydrogels at various temperatures: A fluorescence study. Journal of Macromolecular Science, Part B, 46(3), 581-590. doi:10.1080/00222340701257950
