Branched and Network Polysilanes as Cleavable Macrophotoinitiators

The branched polysilane [(PhMeSi)0.8‐co‐(Et3Si(CH2)2Si)0.2]n (PS‐1) as well as the network polysilane [Et3Si(CH2)3Si]n (PS‐2) have been investigated as new polymerization photoinitiating structures. The behavior of PS‐1 was compared with that of [(PhMeSi)]n to demonstrate the enhancement of the photoinitiation for the branched system. As a result of the Si–Si bond cleavage under light and the formation of reactive silyl radicals or silyl cations, these compounds act as efficient photoinitiators (PIs) for free radical photopolymerization (FRP) and free radical promoted cationic polymerization (FRPCP). The polymerization initiating ability of PS‐1 is higher than that of PS‐2 under air. The initiating ability for the ring‐opening polymerization of epoxides is excellent for PS‐1. These polymeric PIs overcome the classical oxygen inhibition in FRP or FRPCP.