Photopolymerization of Di- and Tetrafunctional Methacrylic Monomers in a Polymeric Medium:  Kinetics and Evidence of Reaction Diffusion Throughout the Photopolymerization Reaction

Abstract

The photopolymerization behavior and reaction kinetics of ethylhexyl methacrylate (EHMA) and ethylene glycol dimethacrylate (EGDMA) monomers in styrene−butadiene−styrene block copolymer (SBS) were studied. For both monomers, di- and tetrafunctional, reaction diffusion was found to be the only mechanism of termination when the polymerization is carried out in this polymeric medium, that is, reaction diffusion controls the termination reaction from the beginning of the reaction. The polymerization of EGDMA in polystyrene and polybutadiene showed similar behavior to that in SBS. Also, the relationship between the individual rate constants k t and k p was studied, and a constant ratio of these kinetic constants was found.

Kinetic investigations on the photopolymerization of di- and tetrafunctional (meth)acrylic monomers in polymeric matrices. ESR and calorimetric studies. I. Reactions under irradiation

“…18,20 All irradiations were done at 40°C in air. Samples were irradiated with a MACAM-Flexicure portable irradiation system provided with a Sylvania 400 W Hg medium-pressure lamp and twin quartz optical fiberguides.…”

“…This finding is an additional confirmation that the mechanism of polymerization in polymeric binders at these monomer concentrations is controlled by reaction diffusion overall the entire range of reaction and confirms our previous results. 18 This occurs even the polymeric system is at T Ͼ T g , and then it is supposed to have not so restricted chain mobility. This 9-line signal remains during all the irradiation time.…”

“…This value is coincident with data given elsewhere for polymerization of multifunctional monomers. 18 In Figure 13 curves of the relative intensity of ESR signal of the propagating radicals versus double bond conversion are shown. As commented before, the signal for HDDMA is stronger than for the monomethacrylates, even its R p is only 2 times higher.…”

“…17 As a part of our research, we have recently described the mechanisms which govern the kinetics of polymerization of methacrylic monomers in polymeric binders. 18 Reaction-diffusion has been evidenced as the only mechanism acting throughout the entire photopolymerization reaction when monomer concentrations in the binder are below 20%. The behavior of the polymerization in polymeric binder has been confirmed as different from that reported for bulk polymerization.…”

Photopolymerisation of styrene initiated by triphenyl bismuthonium ylide

“…In recent years photo-polymerization has attracted much attention because of its increasing technical importance in various applications [1][2][3][4] . Much effort has been devoted to free radical photo-initiated polymerizations, mainly due to the availability of a wide range of photoinitiators 5) .…”