The micellization of four triblock copolymers of the poly(ethylene oxide)x-poly(propylene oxide)y-poly-(ethylene oxide)x type (Pluronic P103, P104, P105, and F88) in aqueous solutions versus temperature is followed by Fouier transform-(FT-) Raman spectroscopy. The frequencies and relative intensities of C-H stretching bands in FT-Raman spectra are sensitive to the local polarity and conformation of block copolymer chains, and their variations with temperature are indicators of micellization. Therefore, the critical micellization temperatures of these copolymers of 10% concentration in aqueous solutions are determined. The deconvolution method is used to resolve the overlapping bands in the C-H stretching region, and the deconvoluted spectra provide information about the structural and microenvironmental changes of ethylene oxide (EO) and propylene oxide (PO) blocks, respectively. The hydration of the EO chains in the corona is found to diminish with increasing temperature, and the conformation changes to a more disordered structure. The structure of PO chains changes from a more polar, gauche conformation at low temperatures to a less polar, stretching conformation at high temperatures. The micellization is explained by the change in structure and microenvironment of the EO and PO units. The results confirm the leading role of the hydrophobic PO units in micellization, and reveal a favorable contribution of the hydrophilic EO units.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

Conclusions:The cells immobilized in magnetic PVA beads could be stably stored and be repeatedly used over 12 times for biodesulfurization. The immobilized cells could be easily separated by magnetic field. Significance and Impact of the Study: Magnetic PVA beads are easy to prepare. The immobilization process in the paper is to increase the efficiency of cells and to decrease the cost of operations.