Kinetics study of the photopolymerisation of donor/acceptor pairs using the differential photocalorimetric technique and the relation of the kinetics data to hydrogels formation

The differential photocalorimetric technique was used to study the rates of photopolymerisation initiated by donor/acceptor pairs with N-vinylpyrrolidinone (NVP) as the donor, and the acceptors were a series of N-hydroxy alkylmaleimides including N-hydroxymethyl maleimide (HMMI), N-(2-hydroxy) ethylmaleimide (HEMI), N-(3-hydroxy) propylmaleimide (HPrMI) and N-(5-hydroxy) pentylmaleimide (HPMI). HPMI/NVP system displays the highest rate of polymerisation followed by HMMI/NVP and then HPrMI/NVP, with HEMI/NVP giving the lowest rate.These donor/acceptor pair systems were subsequently used to initiate the polymerisation of NVP under the influence of UV radiation. With the exception of the HEMI/NVP system, the other three systems produced polymers with characteristics pertaining to that of hydrogel. A previously proposed mechanism (Proceedings of the RadTech Asia ’01 Conference, Kunming, China, 2001, pp. 182–201) was used to explain such phenomenon.