Rapid photopolymerization of octadecyl methacrylate in the solid state

Abstract

Mobility restrictions in solid-state photopolymerization give extremely poor polymerization kinetics. However, photopolymerization of octadecyl methacrylate in the solid state exhibits unique polymerization kinetics and molecular weight distributions. The solid state (at low temperature) in comparison with liquid state (at high temperature) gives significantly improved polymerization kinetics and double bond conversion. More notably, the conversion and polymerization rate of crystalline octadecyl methacrylate were higher than that of liquid dimethacrylates (DEGDMA and EGDMA) studied comparatively. XRD, Real-time FTIR and DSC analysis has illustrated that octadecyl methacrylate polymerized in the solid state without destroying the hexagonal packing of crystalline long alkyl chains. It has been concluded that crystallization occurred in such a manner that acrylic double bonds were arranged in a structure that facilitated rapid minimally activated propagation. Molecular weight distributions were significantly decreased by solid-state photopolymerization. The molecular weight distribution of polymer samples synthesized by solid-state polymerization was independent of reaction conditions i.e. photoinitiator concentration, irradiation wavelength and light intensity.