Manganese phosphinocarbodithioate for RAFT polymerisation with sunlight-induced chain end post-treatment†
A new manganese RAFT agent of the formula Cp(CO)2MnP(Ph)2C(S)SCH(CH3)Ph was synthesized in a good overall yield by a three-step reaction from cymantrene and diphenylphosphine as the main starting materials. This complex proved to be efficient for the control of RAFT polymerisation of St, n-BA and DMAAm. The reaction course could be conveniently monitored by 31P NMR spectroscopy. The controlled character of these polymerisations and the integrity of the polymer chain ends were demonstrated by the synthesis of diblock copolymers of St and n-BA. In the case of long polymerisation times (i.e. for PSt), photo-induced polymer chain coupling reactions were detected. Importantly, removal of the Mn-RAFT-ω-chain end by visible light irradiation led to the formation of a monomodal SH-terminated PSt. These phenomena were evidenced by IR spectroscopy, SEC with RI and UV detection modes and by ESI mass spectrometry.