Mechanically Driven Atom Transfer Radical Polymerization by Piezoelectricity

Abstract

Targeting sustainable and eco-friendly polymer synthesis, we demonstrate here a synergistically catalyzed atom transfer radical polymerization (ATRP) induced and controlled by interplay between ball milling (BM) and piezoelectric nanoparticles (piezoNPs). BM-induced electron transfer can be achieved through piezoNPs deformation under impact force, serving as an external stimulus to mediate polymerization. The ppm level of copper loading is sufficient in fabrication of a polymer with well-defined molecular weight and low polydispersity. High-molecular-weight polymers ranging from 33 to 74 kDa were prepared successfully through DMSO-assisted grinding. Besides, its good performance on availability of water as liquid-assisted grinding additive, the recyclability of piezoNPs, and the formation of cross-linker-free composite resin make our ATRP approach a green and practical option alongside the existent heat-, electro-, and photo-induced methods.

Comparison of Mechano- and PhotoATRP with ZnO Nanocrystals

“…12 These approaches have gained significant attention, as they allow the on-demand spatiotemporal control over the reaction kinetics, 13 under mild conditions. 5 In mechanically controlled ATRP (mechanoATRP), the electrons are generated by piezoelectric nanoparticles dispersed in the ATRP solution upon exposure to ultrasonic shock waves or impact forces, such as ball milling, 14 thereby reducing the Cu(II) catalyst deactivator to form Cu(I) activators. The extent of the electron generation can be controlled by loading of the piezoelectric agents 15 or tuning their physical properties (i.e., dimensions, crystallographic structure, etc.).…”

Shake, shear, and grind! – the evolution of mechanoredox polymerization methodology

“…Other solidstate polymerizations have now been developed as well. 101,102 Future outlook for mechanoredoxmediated polymerizations…”

“…From FRP and RDRP reactions to crosslinking mechanisms using diverse mechanical and piezoelectric sources, we as a field have merely scratched the surface of using mechanoredox catalysis for constructive polymer chemistry. 17,56,[68][69][70]73,76,82,[84][85][86]101 Yet, there are still many unanswered challenges that exist, including the quantification of ''force'' in a given system, recapitulating mechanoredox processes on large scale, exploring the scope of mechanoredox catalysts for specific applications (including the use of organic piezoelectric materials), and pushing the limits on accessing soft materials that are fully inaccessible using solution-state processes. Even more, the utility of mechanoredox chemistry will surely reach beyond polymer synthesis and into more applied areas of research such as the synthesis of anisotropic composites and layered materials.…”

Electron/hole piezocatalysis in chemical reactions

“…PMMA with a monomer conversion of 63.1%, a molecular weight of 6600 g mol −1 , and a dispersity of 1.30 was achieved in the presence of 400 ppm CuBr 2 /TPMA and1.2 wt% ZnO/BaTiO 3 under US (40 kHz, 500 W) for 4 h. The ZnO/BaTiO 3 piezocatalyst showed a high rate of US-mediated ATRP after ten cycles, displaying the excellent recyclability of ZnO/BaTiO 3 . Zhou et al (2023) 199 prepared high molecular weight PMMAs ranging from 33 000 g mol −1 to 74 000 g mol −1 through DMSO-assisted BM over tet-BaTiO 3 (200 nm) in the presence of the CuBr 2 /TPMA complex (1/2). The monomer conversion reached 59–69% after 4 h in all the experiments, while dispersity increased from 1.44 to 1.75.…”