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This book concerned mostly with complex systems and phenomenon of biophysical interest. In Chapter 1, an introduction of Polyelectrolytes, Polyampholytes, Coacervates and Gels is given. In Chapter 2, detail theories regarding Coacervates and Gels are discussed and in Chapter 3, physicochemical properties of agar and gelatin, methods of sample preparations and experimental techniques used are discussed. In chapter 4, formation of agar gelatin complexation, and phase separation thereby forming polymer rich dense phase called coacervate and very least polymer phase called supernatant. The study of this supernatant is discussed in chapter 5, which has been shown to be asymmetric intermolecular aggregates formed due to polarization induced electrostatic interactions. The micro-structural studies of agar-gelatin coacervate is discussed in chapter 6, reveal that this phase is a heterogeneous viscous material. The temporal evolution of the phase stability of agar-gelatin co-hydrogel system was monitored in chapter 7, and internal structures and their combination of agar-gelatin co-hydrogels were studied at chapter 8. In chapter 9, some important future challenges are outlined.

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