Investigation of mechanical and thermodynamic properties of pH‐sensitive poly(N,N‐dimethylaminoethyl methacrylate) hydrogels prepared with different crosslinking agents

pH‐sensitive poly(N,N‐dimethylaminoethyl methacrylate) hydrogels were synthesized by free‐radical crosslinking polymerization using two different crosslinking agents; tetraethylene glycol dimethacrylate (TEGMA) and N,N′‐methylenebis(acrylamide) (BAAm). The influence of the polymerization factors such as the type of the crosslinking agent and the gel preparation concentration on the swelling behavior, the gel strength, the effective crosslinking density and the average chain length between the crosslink points for the resulting hydrogels was investigated. The results of the equilibrium swelling measurements in water showed that the linear swelling ratio of the resulting hydrogels increases with increasing gel preparation concentration. The swelling ratio of PDMAEMA hydrogels crosslinked with BAAm is larger than those for hydrogels crosslinked with TEGMA over the entire range of the polymer network concentration. The hydrogels exhibit very sharp pH‐sensitive phase transition in a very narrow range of pH between 7.7 and 8.0. From the mechanical measurements, it was also found that the linear swelling ratio of resulting hydrogels depends on the crosslinking density and also the type of the crosslinker used in the preparation. The resulting hydrogels are thought to be good candidates for pH‐sensitive drug delivery systems. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers