Thermal gellation and photo-polymerization of di-acrylated Pluronic F 127

Thermal gellation and photo-cross-linking of di-acrylated Pluronic PF 127 (DA-PF 127) were characterized. First, thermo-hysteresis of Pluronic F 127 (PF 127) solution was characterized. Upon heating, thermal gellation was observed at higher temperature with faster heating rate, whereas upon cooling, the re-melting was rather insensitive to cooling rate. Thus, the net thermo-hysteresis effect was more enhanced by increasing heating rate and was more evident at lower concentrations of PF 127. The hysteresis behavior was not affected at all by the presence of acrylated end-groups of di-acrylated DA-PF 127. Next, photo-polymerization of DA-PF 127 was compared with that of non-thermo-sensitive, di-acrylated PEG (DA-PEG). The micellar nature of DA-PF 127 resulted in the beneficial effect on photo-cross-linking reaction. DA-PF 127 showed faster and more effective cross-linking reaction than DA-PEG, characterized by rheometry and FT-IR. Also, by controlling temperature and concentration, morphology of the cross-linked DA-PF 127 hydrogels was varied more significantly than that of DA-PEG hydrogels.