Oscillating Swelling–Shrinking Dynamics and Diffusive Properties of Weakly Cationic Poly(Aminoalkyl Methacrylate)-Based Cryogels: Quantifying the Influence of Polymer Network Parameters

Thermodynamic properties of swelling equilibria and variability of dynamic response of pH-sensitive polybases are examined. Poly(aminoalkyl methacrylate)-based cryogels and hydrogels are prepared in a facile way by crosslinking polymerization of amine functional monomer N,N-dimethylaminoethyl methacrylate (DMAEMA) in the presence of diethyleneglycol dimethacrylate as crosslinker at temperatures below and above freezing point of polymerization solvent, water, via cryogelation and conventional crosslinking polymerization. The effect of polymerization temperature on swelling characteristics of the prepared polybasic gels is investigated as a function of the gel-preparation concentration. The overshooting effect is observed during pH-dependent swelling of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) hydrogels in acidic medium. Protonation/deprotonation of tertiary amine groups in network-forming polymer demonstrates critical swelling behavior as pH of the swelling medium increases. Oscillating swelling–shrinking studies are performed and effective diffusion coefficient of water within PDMAEMA cryogel and hydrogel matrices is estimated using the dynamic swelling profiles. The mechanism of cyclic swelling–shrinking process of PDMAEMA cryogels and hydrogels are analyzed to control their pulsatile output patterns in metabolic oscillations. Considering the swelling process occurs through Fickian diffusion mechanism in acidic solutions, polybasic cryogels and hydrogels prepared in this study are thus proposed as good candidates for delivery applications.