Synthesis and Characterization of Antibacterial Poly(ethylene glycol) Hydrogels

Abstract

Poly(ethylene glycol) (PEG) hydrogels containing tertiary amines were synthesized by thermally-initiated free-radical copolymerization of poly(ethylene glycol) methacrylate (PEGMA), poly(ethylene glycol) dimethacrylate (PEGDMA), and 2-dimethylaminoethyl methacrylate (DMAEMA). The mass fraction of each monomer was varied from 0 to ~1 to determine the composition for optimum mechanical properties and maximum tertiary amine content. Dry films were characterized by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), elemental analysis, dynamical mechanical analysis (DMA), tensile testing, swelling, and differential scanning calorimetry (DSC). The film composition with highest strength, elasticity, swelling, and amine content was found to be 30 wt% PEGDMA due to limited polymerization of DMAEMA with PEGDMA. Films composed of 10 wt% PEGDMA were subsequently quaternized with alkyl bromides of varying chain length (C8, C12, and C16) to impart antibacterial properties to the network. Quaternized films were characterized by elemental analysis, swelling, DSC, and a surface antimicrobial assay. The minimum quaternized DMAEMA concentration for antimicrobial activity was 22 wt% quaternized with C8Br and 30 wt% quaternized with C12Br and C16Br. The most potent alkyl bromide was C8Br followed by C12Br and C16Br. These quaternized PEG-co-poly(DMAEMA) hydrogels show promise as antibacterial materials for biomedical applications.