Determination of phase transition temperatures of PEO-PPO-PEO block copolymer L62 in presence of fermentation media components

This work investigates the effect of various additives/compounds present in fermentation media and products on phase transition temperatures [cloud point (CP), melting point (MP), double cloud point (DCP) and phase separation temperature (PST)] of non-ionic surfactant. Butanol fermentation media and L62 (tri-block copolymer) were considered as a model system. Results showed that the phase transition temperatures strongly depend on concentration of surfactant, butanol and glucose. Phase transition temperature (CP, MP, DCP, and PST) for control i.e. aqueous solution of L62 (3%-15% v/v) were 295-299 K, 297-307 K, 317-322 K, 342-343 K, respectively. Butanol (1%-5% v/v) significantly decreased the phase transition temperatures (7-8 K, 8-11 K, 8-12 K, and 27-29 K, respectively for CP, MP, DCP, and PST) followed by glucose (2-3 K, 2-3 K, 2-7 K and 5-6 K respectively for CP, MP, DCP, and PST) whereas other additives have negligible effect. Presence of both glucose and butanol together had synergistic effect on depression of phase transition temperatures of L62 (9-10 K, 10-14 K, 9-10 K, and 27-29 K, respectively for CP, MP, DCP, and PST). The results from this study provide the estimation of typical cloud point temperature for a range of components present in fermentation media/products. Further, these results will be useful for deciding the conditions for cloud point extraction.