Photoinitiated grafting and graft polymerization of liquid mixtures, adsorbed onto polypropylene, polycaprolactam, and poly(ethy1ene terephthalate) films, containing one of four acryloxy-substituted aromatic diazenes and one of four diacrylate comonomers, in the presence of 1,2-diphenyl-2,2-dimethoxyethanone as photoinitiator, were investigated kinetically at 30 2 2ยฐC. Irradiation was carried out polychromatically, with impinging photoenergy from 2.1 x to 20.5 x lo-@ einstein s-l cm-2; in some of the runs the ultraviolet radiation was filtered. The ratio R between the molar concentration of photoinitiator and the sum of concentrations of dye and diacrylate varied between 0.005 and 0.095; the ratio M between the molar concentration of dye and diacrylate varied between 0.005 and 0.046. The moles of dye and diacrylate n initially deposited per unit apparent polymeric surface S varied between 2 and 74 kmol cm-2.
No selective effect was shown by the presence of dyes in the comonomer mixture. The surface density of grafted molecules at the end of the grafting process was not affected by the photoinitiator concentration (for 0.030 < R < 0.0951, by diacrylate or dye concentrations, or by the kind of polymer substrate. This parameter, on the contrary, clearly depended on nlS, and linearly up to nlS = 30 ymol cm-z. Quantum efficiencies for the two consecutive kinetic processes of grafting and graft polymerization (al and Q2, respectively) were evaluated. The dependency of Ql on R, as well as of Q2 on nIS, are critically discussed on the basis of the proposed mechanism involving grafting of a n oligomeric chain (Ql values up to the order of lo2) followed by a step-by-step graft polymerization (Q2 limiting values of the order of unity).
The sensitizing effect of acryloxy-substituted aromatic diazenes on both Q1 and Q2 is evidenced.