POS1-1507
The power of high pressure: Visible-light-mediated and oxygen-tolerant ATRP for the synthesis of ultra-high molecular weight polymers
When and Where
Nov 30, -0001
8:30am - 9:30am
Presenter(s)
Roksana Wygoda (University of Silesia in Katowice)
Co-Author(s)
Abstract
Ultra-high molecular weight (UHMW) polymers have great potential in biomedical, marine, and construction sectors. However, access to these macromolecules via common reversible-deactivation radical polymerization techniques is highly limited. While aqueous synthesis has been reported predominantly via light-induced reversible addition-fragmentation chain transfer, atom transfer radical polymerization (ATRP) requires an additional stimulus like high pressure. To address this, we developed a high pressure and visible-light irradiation (HP&LI) protocol to synthesize the highest-molecular-weight polymers obtained by ATRP to date.
Extensive research on the effects of pressure on the elementary reactions of the polymerization reveals that it serves as a powerful external physical tool to accelerate propagation, increase the ATRP equilibrium constant, and retard bimolecular termination in diffusion-controlled processes. Within our study, we applied pressures up to 225 MPa and green light (λ=530 nm) to investigate photoredox/copper dual catalysis using OEOMA500 macromonomer, EBiB initiator, eosin Y photocatalyst, and CuBr2/TPMA deactivator in a water/DMSO/PBS mixture, yielding polymers with Mn up to 9,350,000 and Đ<1.49 without deoxygenation of the reaction mixture. We determined an exceptionally large negative apparent reaction volume (ΔVR = -73.60 ± 3.00 cm3mol-1), quantitatively illustrating how high pressure thermodynamically favors the radical generation process. Excellent chain-end fidelity was confirmed by extending a macroinitiator from 33,700 to over 1,234,300 (Đ=1.29). The platform's versatility was also proven by preparing well-defined poly(2-hydroxyethyl acrylate) up to 1,134,000.
In conclusion, combining photoredox/copper catalysis with HP yielded UHMW poly(methacrylates) and poly(acrylates) up to ca. 10 million, previously unattainable by ATRP, revealing the intricate interplay between pressure, rate, catalyst concentration, and solvent.
Extensive research on the effects of pressure on the elementary reactions of the polymerization reveals that it serves as a powerful external physical tool to accelerate propagation, increase the ATRP equilibrium constant, and retard bimolecular termination in diffusion-controlled processes. Within our study, we applied pressures up to 225 MPa and green light (λ=530 nm) to investigate photoredox/copper dual catalysis using OEOMA500 macromonomer, EBiB initiator, eosin Y photocatalyst, and CuBr2/TPMA deactivator in a water/DMSO/PBS mixture, yielding polymers with Mn up to 9,350,000 and Đ<1.49 without deoxygenation of the reaction mixture. We determined an exceptionally large negative apparent reaction volume (ΔVR = -73.60 ± 3.00 cm3mol-1), quantitatively illustrating how high pressure thermodynamically favors the radical generation process. Excellent chain-end fidelity was confirmed by extending a macroinitiator from 33,700 to over 1,234,300 (Đ=1.29). The platform's versatility was also proven by preparing well-defined poly(2-hydroxyethyl acrylate) up to 1,134,000.
In conclusion, combining photoredox/copper catalysis with HP yielded UHMW poly(methacrylates) and poly(acrylates) up to ca. 10 million, previously unattainable by ATRP, revealing the intricate interplay between pressure, rate, catalyst concentration, and solvent.
