Hydrophobically Associated Poly(acrylamide/octadecyl acrylate)-Carboxymethyl Cellulose Hydrogels: Synthesis, Characterization, and Shape Memory Ability

In this study, hydrophobic modified poly(acrylamide/octadecyl acrylate) (poly(AAm/C18)) and poly(acrylamide/octadecyl acrylate)-carboxymethyl cellulose (poly(AAm/C18)-CMC) hydrogels with high mechanical strength and shape memory properties were synthesized by random copolymerization method. Hydrogel synthesis was successfully carried out in one step on the basis of the hydrophobic monomer units carrying alkyl side chains included in the hydrophilic polymer network, and these hydrophobes clustered in water and acted as crosslinks. Hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), Differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results showed that with the increase of the amount of hydrophobic monomer (C18) in the hydrogels, the crystal regions in the hydrogel structure increased. The swelling behaviour of the hydrogels was investigated as a function of the hydrophobic monomer content. Experimental swelling data confirmed the DSC and XRD results. The shape memory properties of hydrogels containing CMC were investigated. The new shape of the hydrogels was fixed by complexation between CMC and metal (M 2+ and M 3+ valence) ions.