ARTICLE This journal isThe ability of a RAFT agent to control the polymerization of a monomer is dictated by the structures of both the monomer and the RAFT agent. In this paper, the polymerization of Nvinylpyrrolidone was examined with a series of cyanomethyl N-aryl-N-pyridyl dithiocarbamates [(4-RʹPh)N(py)C(=S)SCH 2 CN] varying in the substituent (Rʹ) at the 4position on the phenyl ring. The polymerization of N-vinylpyrrolidone was best controlled when Rʹ was methoxy; one of the least active RAFT agents in the series. The preservation of RAFT agent functionality was demonstrated by chain extension experiments with further Nvinylpyrrolidone. Again best control again was found for the RAFT agent with Rʹ=MeOPh. The utility of this RAFT agent was also proved with the preparation of poly( Nisopropylacrylamide)-block-poly(N-vinylpyrrolidone).

Thermolysis is examined as a method for complete desulfurization of reversible addition-fragmentation chain transfer (RAFT)-synthesized polymers prepared with acid/base "switchable" N-methyl-N-pyridyldithiocarbamates [RS CZ or RS CZH ]. Macro-RAFT agents from more activated monomers (MAMs) (i.e., styrene (St), N-isopropylacrylamide (NIPAm), and methyl methacrylate (MMA)) with RS CZH and less activated monomers (LAMs) (i.e., vinyl acetate (VAc) and N-vinylpyrolidone (NVP)) with RS CZ are prepared by RAFT polymerization and analyzed by thermogravimetric analysis. In all cases, a mass loss consistent with loss of the end group (ZCS H) is observed at temperatures lower than, and largely discrete from, that required for further degradation of the polymer. The temperatures for end group loss and the new end groups formed are strongly dependent on the identity of the R(P) and the state of the pyridyl Z group; increasing in the series poly(MMA) < poly(St) ∼ poly(NIPAm) << poly(VAc) ∼ poly(NVP) for S CZ and poly(MMA) < poly(St) ∼ poly(NIPAm) for S CZH . Clean end group removal is possible for poly(St) and poly(NVP). For poly(NIPAm), the thiocarbonyl chain end is removed, but the end group identity is less certain. For poly(MMA) and poly(VAc), some degradation of the polymer accompanies end group loss under the conditions used and further refinement of the process is required.

We report on low molar mass cationic RAFT agents that provide predictable molar mass and low molar mass dispersities (Đm) in ab initio emulsion polymerization.