Swelling behavior depending on the charge density of sulfonic acid gels and acrylic acid gels in water and buffers was reviewed on the author’s results.The counterion condensation in the sulfonate gels and their volume phase transition were summarized here
showing the hystersis during the phase transition in mixed organic solvents.The driving force for the transition and concept of polyelectrolyte and ionomer were interpreted with the multiplet formation when decreasing the media polarity.