Photo-induced polymerization of diethylene glycol diacrylate in the presence of poly(methyl methacrylate): 1—Polymerization without any photoinitiator

With a view to the manufacture of printing plates, films consisting of diethylene glycol diacrylate and poly(methyl methacrylate) acting as a binding agent were irradiated with UV light. The monomer absorbs UV radiation below 300 nm, whereas the resulting polymer as well as the poly(methyl methacrylate) only weakly contribute to total absorption.

On irradiation, UV light of wavelengths below 300 nm initiates polymerization of the monomer also in the absence of any photo-initiator and induces degradation of polymer chains: the poly(methyl methacrylate) depolymerizes to the monomer methyl methacrylate, whereas poly(diethylene glycol diacrylate) does not decompose to degradation products with CC double bonds. No degradation occurs when the films are irradiated with UV radiation of wavelength above 300 nm, but polymerization of diethylene glycol diacrylate is initiated to some extent under these conditions.

Annealing at 60°C of films irradiated at room temperature to maximum conversion results by thermal polymerization in a loss of pendant double bonds of diacrylate monomer units which are incorporated into the network only by polymerization via one double bond.