Dimethyl amino phenyl substituted silver phthalocyanine as a UV- and visible-light absorbing photoinitiator: in situ preparation of silver/polymer nanocomposites†
A novel visible-light absorbing silver dimethyl amino phenyl substituted phthalocyanine photoinitiator (dmaph-Ag(II)Pc) for free-radical (FRP) and cationic (CP) polymerizations in laminate and under air is reported. The photoinduced electron transfer reactions of excited dmaph-Ag(II)Pc in the presence and absence of an iodonium salt (Iod) resulted in the formation of a Brønsted acid and radical species capable of initiating CP and FRP, respectively. The photophysical and photochemical properties of the photoinitiator are evaluated in detail by computational and spectroscopic investigations, and the kinetics of the polymerizations are studied. It was demonstrated that the described photoinitiating system is highly efficient in the simultaneous cationic or free-radical polymerization and silver ion reduction. The nanocomposites formed this way contain spherical shaped silver nanoparticles homogenously dispersed in the polymer matrix with a narrow size distribution between 5 and 20 nm.