Temperature-sensitive poly[(2-diethylaminoethyl methacrylate)-co-(N,N-dimethylacrylamide)] [P(DEAEMA-co-DMAAm)] hydrogels with five different DMAAm contents were synthesized with and without the addition of sodium carbonate as porosity generator. The synthesized hydrogels were characterized with dry gel density measurements, scanning electron microscopy observation and the determination of swelling ratio. The influence of the pore-forming agent and content of DMAAm on swelling ratio and network parameters such as polymer-solvent interaction parameter (χ), average molecular mass between crosslinks (M c ) and mesh size (ζ ) of the cryogels are reported and discussed. The swelling and deswelling rates of the porous hydrogels are much faster than for the same type of hydrogels prepared via conventional methods. At a temperature below the volume phase transition temperature, the macroporous hydrogels also absorbed larger amounts water compared to that of conventional hydrogels and showed obviously higher equilibrated swelling ratios in aqueous medium. In particular, the unique macroporous structure provided numerous water channels for water diffusion in or out of the matrix and, therefore, an improved response rate to the external temperature changes during the deswelling and swelling processes. These properties are attributed to the macroporous and regularly arranged network of the porous hydrogels. Scanning electron micrographs reveal that the macroporous network structure of the hydrogels can be adjusted by applying porosity generation methods during the polymerization reaction.

Summary: Temperature‐sensitive P(DEAEMA‐co‐DMAAm) cryogels with five different DMAAm contents were synthesized via a two‐step polymerization method, the initial polymerization being conducted for various times at 22 °C, followed by polymerization at −26 °C for 24 h. The influence of the first‐step time and the content of DMAAm on the swelling ratio and network parameters such as the polymer/solvent interaction parameter, the average molecular mass between crosslinks, and the mesh size of the cryogels were reported and discussed. The swelling studies indicated that the swelling increased in the following order: 22C45 > 22C30 > 22C15 > 22C0. The cryogels exhibited swelling/deswelling transitions (reentrant phenomena) in water depending on temperature. These properties were attributed to the macroporous and regularly arranged network of the cryogels. Scanning electron microscope graphs reveal that the macroporous network structure of the cryogels can be adjusted by applying a two‐step polymerization.Chemical structure of the P(DEAEMA‐co‐DMAAm) cryogels.magnified imageChemical structure of the P(DEAEMA‐co‐DMAAm) cryogels.