4. Conclusions
It was shown that a 0.75% KC/0.75% gelatin mixed system
underwent a transition from complex coacervation governed by
electrostatic interaction to that reinforced by hydrogen bonding
upon cooling. The increasing of turbidity at 40 ◦C is not induced by
the ordering of two polymers both of which are still in coiled state.
Urea and glycerol have been used to identify the driving force in this
transition. The transition is found to be mainly due to the hydrogen
bond formation between KC and gelatin that reinforces the
existing complex coacervation. pH, ionic strength, mixing concentration
and ratio are the major parameters that affect the hydrogen
bonding reinforced complex coacervation. Their effects should be
explained in the context of electrostatic complexation. Electrostatic
complexation seems to be an advantage for the subsequent formation
of hydrogen bonding upon cooling. The study would provide