Modulating the mechanical properties of photopolymerised polyethylene glycol–polypropylene glycol hydrogels for bone regeneration

Hydrogels formulated from single polymers are often insufficient in terms of their mechanical properties for use as bone substitute materials. Hence, hydrogels synthesised from combinations of polymers have been investigated to optimise the performance of such materials. In the current study, polypropylene glycol dimethacrylate was added to polyethylene glycol dimethacrylate of a variety of molecular weights and photopolymerised to form a series of hydrogels. Polyethylene glycol and polypropylene glycol have the same chemical structure with the exception of a methyl group on the later. Herein, the influence of the methyl group of polypropylene glycol on the mechanical properties of hydrogels for bone regeneration applications is reported. For both unconfined and cyclic compression testing, results demonstrated that the incorporation of PEGDMA into the precursor improves the compression strength of the hydrogels. For example, in unconfined compression tests the Young’s modulus varied between 6.62 ± 0.31 MPa and 8.08 ± 0.81 MPa with the incorporation of PEGDMA 400.