Tailoring the viscoelastic, swelling kinetics and antibacterial behavior of poly(ethylene glycol)-based hydrogels with polycaprolactone

Abstract Polyethylene glycol (PEG) diacrylate was photocured with poly( ɛ -caprolactone) (PCL) diacrylate and the thermal, viscoelastic and antibacterial properties were studied. The aim was to reinforce the hydrogels and induce shape memory behavior. The diacrylates of PEG of 3350 g/mol and PCL of 10,000 g/mol were photocured in the presence of a crosslinker tetrathiol and photoinitiator. The concentration of PCL macromers were varied from 10 to 50 mol%. Through scanning electron microscopy, differential scanning calorimetry, and rheology the influence of PCL was investigated. The dry PEG–PCL networks exhibited only one melting endotherm due to transition overlapping. The dry samples exhibited complex spherulitic morphology due to PEG and PCL competitive crystallization. Upon wetting, the crystalline phase of PEG “melted” away leaving only the crystalline phase of PCL, which acted as nanoreinforcer thus enabling a hydrogel with robust shear modulus. Moreover, PCL tuned the swelling rate, total swell and pore size of the hydrogels and its crystals melting transition provided for an activation temperature for shape memory behavior. Furthermore, antimicrobial activity of silver loaded hydrogels was investigated through exposure to Pseudomonas aeruginosa and Staphylococcus aureus with inoculation to a controlled cell density. The results showed that there was antibacterial activity even after 168 h. Therefore, PCL was effective in fine tuning the mechanical properties, swelling ratio and water uptake kinetics of PEG-based hydrogels thus opening up opportunities for intelligent substrates for antibacterial properties and drug delivery.