Manganese phosphinocarbodithioate for RAFT polymerisation with sunlight-induced chain end post-treatment

Abstract

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.