Non-Osmotic Hydrogels: A Rational Strategy for Safely Degradable Hydrogels.

Hydrogels are promising materials for biomedical applications, where timely degradation is often preferred. In the conventional design, however, the cleavage of polymer networks essentially causes considerable morphological changes (i.e., degradation-induced swelling), triggering various medical complications. Herein, we report a rational strategy to suppress the degradation-induced swelling based on the synthetic control of the polymer-solvent interaction parameter (χ) of constituent polymer networks. The resultant hydrogels with an optimal χ parameter (χ37 °C ≈0.53; non-osmostic hydrogels) displayed the capability to retain their original shape and degrade without generating significant swelling pressure under physiological conditions (Π37 °C <1 kPa). This concept of the safely degradable non-osmotic hydrogel is theoretically universal, and can be exploited for other types of synthetic hydrogels in various settings.