Volume phase transition

Saito, S., Konno, M and Inomata, H. Volume Phase Transition of N-Alkylacrylamide Gels. Vo), 109, pp. 207-232. 

S Hirotsu, Y Hirokawa, T Tanaka. Volume phase transitions of ionized N-isopro-pylacrylamide gels. J Chem Phys 87 1392-1395, 1987. 

Otake, K., Inomata, H., Konno, M., and Saito, S. Thermal analysis of the volume phase transition with Al-isopropylacrylamide gels. Macromolecules 1990, 23, 283-289. 

The goal of this research is to develop a new class of bioresponsive materials that undergo rapid, large-magnitude, volume-phase transitions in response to specific biological stimuli. Our approach to these materials is based on two fundamental aspects of hydrogels (1) hydrogel solvation/desolvation thermodynamics can be perturbed... and... 

Note 3 An example of covalent polymer gels is nei-poly(A-isopropylacrylamide) swollen in water, which shows volume phase transition during heating. 

Figure 19.1 shows the temperature-dependent volume-phase transitions of NIPA-based hydrogels. It is suggested that formation of a complex between bioactive molecules and functional groups of hydrogels is responsible for immobilization of the former. The lower critical solution temperature (LCST) of PNIPA can be tuned to the required value by introducing hydrophobic or hydrophilic fragments. 

Volume Phase Transition and Related Phenomena of Polymer Gels... 

Volume Phase Transition of Gels. The volume-phase transition was experimentally discovered for a partially ionized acrylamide gel in a mixture of acetone and water by Tanaka in 1978 [19],... 

In Sect. 2, we briefly review the thermodynamics of the volume phase transition. In Sect. 3, the dynamics of gels are discussed and the theory of dynamic light scattering (DLS) is reviewed. Section 4 describes the current knowledge of the microscopic gel structure as shown by small-angle neutron... 

Similarly to the van der Waals fluid, polymer gels were found to have a volume-phase transition. In the case of gels, the gas and liquid phases correspond to the swollen and collapsed (shrunken) phases, respectively. The prototype of the free energy expression was given by [9, 10, 18]. 

Fig. 4. Phase diagram of gels, fl and v denote the osmotic pressure and the microscopic volume of gel. (v = a3/< >). This Il-v plane corresponds to P-V plane of van der Waals fluids. At % < Xc. n is a convex function of v. At > Xc. a volume phase transition from collapsed to swollen states or vice versa occurs. Note II can be either positive or negative...

Prediction of Discontinuous Volume Phase Transition with Respect to Temperature... 

Fig. 6. Equilibrium volume of ionized AJ-isopropylacrylamide (NIPA) gels in water show discontinuous volume phase transition in response to temperature. The values shown in the diagram indicate the amount of ionizable group (sodium acrylate) incorporated in 700 mM NIPA...

The classic theory discussed in the previous section describes the essential feature of the volume phase transition of polymer gels. However, a quantitative... 

---