Synthesis and characterisation of PEGDA-based hydrogels crosslinked with pentaerythritol tetrakis (3-Mercaptopropionate)

Abstract

PEGDA-based hydrogels have been synthesised successfully by photopolymerisation and Michael-type addition reaction. Before the hydrogel is prepared, degree of acrylation is determined by 1H NMR characterisation. Photo-crosslinked hydrogels has been characterised by FTIR and show successful thiol-linkage with the acrylate moieties. Selected PEGDA-based hydrogels have been put through Instron tensile and cyclic tests, and show highly elastic behaviour. The rheometry test reaffirmed the high elastic behaviour of selected PEGDA-based hydrogels through its corresponding high storage moduli for PEGDA macromers synthesized from PEG of Mw 8000 Da and 10000 Da. Equilibrium swelling test indicates the high water content and swelling ratio of photo-crosslinked hydrogels synthesized with PEGDA macromers with high degree of acrylation. Similar trend is found in Michael-type addition crosslinked hydrogels synthesized from PEG of Mw 4000 Da, 8000 Da and 10000 Da.

In addition, higher wt% concentration of PEGDA involved in the preparation of Michael-type addition crosslinked hydrogels indicate better rheological property in terms of higher storage moduli. Equilibrium swelling test is performed to determine the composition of the three types of water existing in hydrogels. During degradation test, unexpected mass loss behaviour is observed in photo-crosslinked PEGDA-based hydrogels with high composition of non-freezing water indicated quantitatively by DSC test.