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Gelation of hyaluronic acid through annealing
Author(s) -
Fujiwara Junji,
Takahashi Masato,
Hatakeyama Tatsuko,
Hatakeyama Hyoe
Publication year - 2000
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/1097-0126(200012)49:12<1604::aid-pi558>3.0.co;2-4
Subject(s) - differential scanning calorimetry , annealing (glass) , enthalpy , materials science , molecule , dissociation (chemistry) , chemistry , analytical chemistry (journal) , polymer chemistry , chemical engineering , thermodynamics , chromatography , composite material , organic chemistry , engineering , physics
The effect of annealing, at a temperature higher than that of the gel‐sol transition, on the junction formation in the gelation process of sodium hyaluronate/water systems was investigated by the falling ball method (FBM) and differential scanning calorimetry (DSC). FBM measurements were carried out for 1, 2 and 3 wt% solutions. Gel formation was not observed for 1 and 2 wt% solutions, but for 3 wt% solution, gel formation was observed for annealing temperature T = 60 °C and annealing time longer than 6 h. The gel‐sol transition temperature measured by FBM was about 15 °C. Gel formation was not observed in measurements at T = 40 °C and 50 °C. However, the enthalpy of melting, Δ H m per 1 mg of water, (determined by DSC) changed in a complex manner during annealing at 60 °C, ie Δ H m increased in the initial stage and then decreased in the later stage. This indicates that the amount of non‐freezing water decreased in the initial stage and then increased in the latter stage. The initial stage corresponds to processes of dissociation of the assemblies of hyaluronic acid molecules by desorbing water molecules and subsequent homogenization of the system. However in the later stage, a junction structure which enables the system to form gels was thought to be formed. © 2000 Society of Chemical Industry