Smart thermosensitive poly (N-vinylcaprolactam) based hydrogels for biomedical applications

Photopolymerisation is an attractive technique used in biomedical applications as it can provide rapid reaction rates with excellent temporal and spatial control features and unique tuneable properties. This fabrication technique provides the potential to reduce invasiveness and cost for biomedical and biotechnological applications. In this study physically crosslinked hydrogels based on N-vinylcaprolactam with different weight percentages of photoinitiator were prepared via free radical polymerisation. These temperature responsive polymers were characterised in terms of glass transition, lower critical solution temperature (LCST) and swelling properties. Results showed that photoinitiator concentration had minimal effect on phase transition temperature as LCST was ~31°C for samples tested. Swelling studies results showed that hydrogen bonding dominates below its LCST as the polymers dissolved within 5hrs.This was compared to above its LCST where both hydrogen bonding weakens and the hydrophobic components dominate in the system. Finally, the photoinitiator concentration altered the glass transition temperature of the hydrogels where values ranged from 89-118 °C.