文摘
In this work, the reversible addition-fragmentation chain transfer (RAFT) polymerization of vinyl acetate (VAc) was successfully performed at room temperature using 60Co ¦Ã-irradiation as the initiation source. Under the dose rate of 10 Gy/min irradiation, the polymerization proceeded smoothly and converted approximately 90 % of the monomer within 7 h. The molecular weight distribution (Mw/Mn) remained narrow (Mw/Mn < 1.35) up to 90 % conversion. Compared to AIBN-initiated RAFT polymerization at 60 ¡ãC, 60Co ¦Ã-irradiation-initiated RAFT polymerization is a technique that can better control the molecular weight, especially at high conversion. The 1H NMR spectra and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry confirmed that most of the chain ends of poly(VAc) (PVAc) from ¦Ã-irradiated RAFT polymerization were living and can be reactivated for chain-extension reactions. The microstructures of PVAc from 60Co ¦Ã-irradiated RAFT polymerization (almost head-to-tail addition) and AIBN-initiated RAFT polymerization (5 % tail-to-tail addition) were different, as revealed by the 13C NMR spectra. For the first time, 60Co ¦Ã-irradiation was used as an initiation source for RAFT polymerization of VAc at room temperature.
