Photoinduced Conjugation of Dithioester- and Trithiocarbonate-Functional RAFT Polymers with Alkenes
Till Gruendling
Michael Kaupp
James P. Blinco
Christopher Barner-Kowollik
10.1021/ma101893u.s001
https://acs.figshare.com/articles/journal_contribution/Photoinduced_Conjugation_of_Dithioester_and_Trithiocarbonate_Functional_RAFT_Polymers_with_Alkenes/2699488
We report the photoinduced conjugation of polymers synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization with a number of low molecular weight (functional) olefins. Upon irradiation of a solution of an aliphatic alkene and the benzyl dithioacetic acid ester (CPDA) or dodecyl trithiocarbonate (DoPAT) functional poly(alkyl acrylate) at the absorption wavelength of the thiocarbonyl group (315 nm), incorporation of the alkene at the polymer chain-end occurred. The most efficient systems identified with regard to the rate of reaction and yield were poly(butyl acrylate)/CPDA/ethyl vinyl ether (78% monoinsertion product after 1 h) and poly(butyl acrylate)/CPDA/1-pentene (73% insertion product after 7 h) at ambient temperature. An in-depth analysis of the reaction mechanism by <sup>1</sup>H NMR and online size-exclusion chromatography-electrospray ionization tandem mass spectrometry (SEC/ESI−MS<sup>n</sup>) revealed that a possible [2 + 2] photoaddition mechanism of conjugation does not take place. Instead, fast β-cleavage of the photoexcited RAFT-end group with subsequent radical addition of an alkene was observed for all employed systems. The presented reaction thus provides a means of spatial and temporal control for the conjugation of alkenes to thiocarbonyl thio-capped macromolecules via the use of UV radiation.
2011-01-11 00:00:00
UV radiation
aliphatic alkene
Photoinduced Conjugation
benzyl dithioacetic acid ester
ambient temperature
1 H NMR
7 h
reaction mechanism
thiocarbonyl
poly
SEC
1 h
dodecyl trithiocarbonate
polymer
photoinduced conjugation
CPDA
absorption wavelength
acrylate
AlkenesWe report