2017
DOI: 10.1021/acsmacrolett.7b00038
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Catalyst-Free Photoinduced End-Group Removal of Thiocarbonylthio Functionality

Abstract: An initiator-and catalyst-free method for polymer end-group modification has been designed. Under long-wave ultraviolet irradiation, polymers with thiocarbonylthio end groups undergo photolytic cleavage to reveal an active macroradical capable of irreversible termination with a suitable hydrogen source. This straightforward method was successfully demonstrated by the removal of a range of end groups that commonly result from reversible addition−fragmentation chain transfer or photoiniferter polymerizations, in… Show more

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Cited by 67 publications
(75 citation statements)
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“…Neither a decrease in I polyrotaxane nor increase in I αCD remarkably occurred under either condition in the SEC (Figure B,C), suggesting that the dissociation was triggered by UV irradiation. This is consistent with the previous report that UV irradiation induces the photo‐cleavage of thiocarbonylthio groups to generate radical species . In order to further investigate whether the photo‐cleavage of CPADB stoppers trigger the dissociation of the αCD/PEG‐CPADB polyrotaxanes, polyrotaxane capped with adamantanes (Ad) was prepared as a control (αCD/PEG‐Ad polyrotaxane) (Figure S3, Supporting Information).…”
supporting
confidence: 85%
“…Neither a decrease in I polyrotaxane nor increase in I αCD remarkably occurred under either condition in the SEC (Figure B,C), suggesting that the dissociation was triggered by UV irradiation. This is consistent with the previous report that UV irradiation induces the photo‐cleavage of thiocarbonylthio groups to generate radical species . In order to further investigate whether the photo‐cleavage of CPADB stoppers trigger the dissociation of the αCD/PEG‐CPADB polyrotaxanes, polyrotaxane capped with adamantanes (Ad) was prepared as a control (αCD/PEG‐Ad polyrotaxane) (Figure S3, Supporting Information).…”
supporting
confidence: 85%
“…To sterically access the ω chain-end for catalytic activation, a photoinduced end-group removal strategy 30 previously developed in our group was used as the key step in generating a hydrogen capped PMMA (PMMA-H) that contained a sterically unhindered ester on the ω terminus. Transesterification of PMMA-H resulted in the monosubstituted ω-functionalized product (PMMA-Bn) which was verified through MALDI-TOF-MS ( Fig.…”
Section: Resultsmentioning
confidence: 99%
“…In the case of dithiolate esters, visible light is reported to be ineffective at initiating efficient polymerization whereas UV photolysis effects polymerization 7,15,16 . However, UV photolysis results in poor end group fidelity, due to unspecified side reactions that degrade the dithiolate ester 16,17 . The trithiocarbonate RAFT agents are effective photoiniferters under both UV and visible light photolysis, although the photochemical efficiency of these processes is suggested to be modest at best 13,[18][19][20][21][22][23] .…”
Section: Scheme 1 Initiation and Propagation In A Raft Polymerizatiomentioning
confidence: 99%