[[Polymer Solutions]] > [!Definition] > Polymers with groups that become charged when in solution Solid salt: Counter ions are attached electrostatically to backbone After dissolution in water: 1) osmotic pressure drives counterions farther away 2) charges on polymer start to repel each other without counter ions, polymer elongates Some polymers are superabsorbent (ex: polyacrylate) - Linear polymers become infiinitely diluted - Crosslinked polymers (hydrogels) will retain shape (ex: water beads) Adding salts to an aqueous polymer solution will cause the polymer to **shrink** - less osmotic pressure, more counter ions, less repulsion pH responsive gels: When acid is added, backbone is protonated and polymer is no longer a polyelectrolyte, so it shrinks