A well-controlled piezoelectrically mediated reversible addition–fragmentation chain-transfer polymerization (piezo-RAFT) was carried out under ultrasonic agitation with piezoelectric ZnO nanoparticles as the mechanochemical transducer. The resulting polymer had high end-group fidelity, low dispersity, and capacity for chain extension. This piezoelectrically mediated polymerization involves the generation of the alkyl radical through an electron transfer process from the piezoelectric nanoparticle to alkyl bromide, which was also verified by 1H NMR, liquid chromatography–mass spectrometry (LC-MS), electron spin resonance (ESR), and density functional theory (DFT) calculation. This chemistry was further adopted in curing composite resins to circumvent the light penetration limit of ultraviolet (UV) curing. This work opens a new avenue for piezoelectrically mediated chemistry and shows good potential in curing applications.

Comprehensive Summary Recently, piezocatalysis has attracted considerable attention as a new type of renewable mechanical energy conversion technology, which relies on the strain induced polarization of the piezoelectric material. This new technology has been extensively applied in the applications of water splitting, water remediation, gas purification and tumor therapy. Despite the rapid development in the piezocatalysis, the utilization of piezoelectric materials for synthetic purpose is still under exploration. Piezoelectric means to promote organic reactions expand the scope of piezoelectrically mediated reactions and show successes in both organic and polymer synthesis. Herein, we provide a comprehensive review on recent progress of piezoelectrically mediated reactions, catalytic mechanisms and applications in the last few years. The limitations and future directions of this area are also discussed. We believe this review will provide new insights into the underlying mechanism of piezoelectric mediated electron transfer process and guide the design of new chemistry.

Comprehensive SummaryMechanoredox chemistry that uses highly polarized piezoelectric materials as mechanoredox catalysts to promote redox reactions has emerged recently. It provides an alternative approach alongside the existing polymerization methods. Despite recent accomplishments, determining the quantitative relationship between the structure of ZnO and its catalytic performance for polymerization is still challenging. Herein, we prepared various ZnO crystals with different polar facets ratios to achieve efficient mechanically induced reversible addition‐fragmentation chain transfer polymerization (mechano‐RAFT). ZnO prepared from Zn(NO3)2 showed a high polar facet ratio of 1.66 and offered the highest catalytic activity among all ZnO samples. A near‐quantitative initiator efficiency of 99.5% and narrow molecular weight distribution were achieved for the polymerization of n‐butyl acrylate. Furthermore, the high chain‐end fidelity and chain extension capability were also evidenced by MALDI‐TOF MS and GPC analysis. This work highlighted the significant contribution of polar facets in ZnO to its catalytic activity and will guide the design of mechanoredox catalysis with superior catalytic performance in the future.