Visible-Light-Induced Living/Controlled Radical Copolymerization of 1-Octene and Acrylic Monomers Mediated by Organocobalt Complexes

Abstract

Compared with homopolymers, the copolymers exhibit improved properties, providing a broad application prospect. Herein, we report the visible-light-induced living/controlled radical copolymerization of acrylates or acrylamides and 1-octene mediated by organocobalt complexes at ambient temperature, giving copolymers with well-predictable molecular weights from 4400 to 27200 and low polydispersities in the range 1.17–1.28. The acrylic monomer reactivity ratio was calculated by monomer conversion and molar fraction of 1-octene without a complex fitting process. The electron-withdrawing groups on acrylic monomers resulted in low reactivity ratio down to 1.1 along with high molar fraction of 1-octene up to 34%, while electron-donating group led to increased reactivity ratio as 43 with a declined molar fraction of 1-octene as 3%. For the first time, a linear relationship between the logarithm of the reactivity ratio and the atomic charge of the propagating radical was observed, which affords a potential quantitative model to evaluate the electronic effect in other copolymerization systems.

Organo‐Cobalt Complexes in Reversible‐Deactivation Radical Polymerization

“…We used the organo‐cobalt complex of (Salen)Co−CO 2 CH 3 associated with the photo‐initiator, TPO, to mediate the visible‐light induced copolymerization of acrylates and 1‐octene (1‐Oct) in the ambient temperature (Scheme 7). [75] The living nature of copolymerization was demonstrated by linearly increased molecular weight with conversion, the match between the experimental M n and the theoretical values, a narrow molecular weight distribution (Figure 10a), and the successful chain extension to PMA and PDMA (Figure 10b). The copolymerization was proposed to be controlled via an RT pathway because the polymerization could be initiated with the absence of TPO.…”

“… Structures of (Salen)Co III −CO 2 CH 3 , 2,4,6‐trimethylbenzoyl diphenyl phosphine oxide (TPO) and the acrylates copolymerized with 1‐octene: (a) 1‐octene (1‐Oct), (b) methyl acrylate (MA), (c) tert ‐butyl acrylate ( t BA), (d) N , N ‐dimethylacrylamide (DMA), (e) 2,2,3,3‐tetrafluoropropyl acrylate (TFPA), (f) 2,2,2‐trifluoroethyl acrylate (TFEA), (g) 1,1,1,3,3,3‐hexafluoroisopropyl acrylate (HFIPA) [75] …”

“… (a) Evolution of molecular weight, polydispersity and molar fraction of 1‐ Oct versus MA conversion in the copolymerization of MA and 1‐Oct under the condition of [MA] 0 /[1‐Oct] 0 /[(Salen)Co III −CO 2 CH 3 ] 0 /[TPO] 0 =150/150/1/2, [MA] 0 =[1‐Oct] 0 =1.0 mol L −1 , light intensity was 6 mW cm −2 , set MF(1‐Oct) as 10 % to calculate theoretical M n . (b) GPC traces of poly(MA‐ co ‐1‐Oct) macroinitiator, as well as block copolymers with MA and DMA by visible‐light induced polymerization mediated by organo‐cobalt complex [75] …”

Advances in Polymerizations Modulated by External Stimuli

“…(Salen)­Co–CO 2 CH 3 was also used in the presence of TPO, generating both phosphorus- and carbon-centered radicals upon irradiation, which resulted in the formation of phosphorus-capped polymer chains because of the high reactivity of phosphorus radicals . More recently, (salen)­Co–CO 2 CH 3 was used for the copolymerization of 1-octene and acrylates under visible-light irradiation (420–780 nm) while maintaining good molecular weight control . However, while this (salen)­Co–CO 2 CH 3 system exhibited good molecular weight control, it did not exhibit any temporal control.…”

Photoinduced SET to access olefin-acrylate copolymers

“…Despite these complicating factors, copolymer materials comprised of both activated and unactivated monomer units remain desirable due to improvements in many material properties when compared to homopolymers of either monomer. 2,[4][5][6][7][8][9][10][11][12] Radical copolymerizations of olefins with activated monomers face a substantial barrier that precludes facile copolymerization. The enchainment of a given monomer in a radical copolymerization is governed by its feed ratio and the reactivity ratios of the two monomers.…”