Optimization of synthetic hydrogel biomaterials through control of microstructure

The degradation behavior of highly swollen, chemically crosslinked hydrogels was characterized by monitoring changes in their mass loss, degree of swelling, and compressive modulus. The hydrogels were used as model systems to investigate the hydrolytic degradation process in crosslinked networks. The trends of the three measured properties differ substantially from those seen for linear degradable systems but can still be accurately predicted using hydrolysis kinetics and network structure. Experimental results verify theoretical predictions and show the modulus to decrease exponentially with time while the volumetric swelling ratios for these gels increase exponentially. The characteristic time constants for these two functions, as well as the overall degradation time-scale, are influenced greatly by the network structure. Thermodynamic relationships are used to explain these trends as well as to relate the observed tradeoff between the two desirable properties of mechanical strength and water content.