Temperature-responsive Gel
convenient LCST like pNIPAAm

poly(2-3)Glucose phase transitions

Poly(2,3)glucose forms temperature-responsive gels. Aqueous solutions are liquids below their lower critical solution temperature and hydrogels above their transition temperature. These physically cross linked gels have precise (+/- 0.5 C) transition temperatures. Poly(2,3)glucoses T1-25, T1-30, and T1-35 have transition temperatures of 25, 30 and 35 in phosphate buffered saline 0.01 M. By linearly blending the two products with transitions that bracket another temperature, any intermediate transition temperature can be attained and temperature shifts due to other diluents can be accomodated.

The viscoelastic properties of a poly(2,3)glucose solution change dramatically and abruptly at the transition temperature. The sol-gel transition is endothermic and entropic. The heat of transition is ~20 J/g of polymer. The liquid to gel transition is very rapid, while the gel to liquid transition is slower and displays hysteresis. Applications of temperature-responsive gels utilize this hysteresis. For example islet cells can be suspended in a 10% T1-25 solution at 24 C, encapsulated at 37 C, and then handled at 24 C for hours before they are implanted in a murine kidney capsule.

Gel transition temperature decreases with concentration
Gels are named by their nominal transition temperature. Tgel decreases with polymer concentration. Solutes can also reduce Tgel. These effects can be accommodated by blending.
Blended solutions linearly combine in transition temperature.
The solution to gel transition occurs with temperature increase.

Entropic Transition

Differential scanning calorimetry of poly (2-3) glucose 5 wt% solution. 5 C/min. The sol-gel transition occurs with heating the gel-sol transition occurs with cooling.