Metal-free atom transfer radical polymerization with ppm catalyst loading under sunlight

Qiang Ma,Yu Jiang,Li Ji,Xun Zhang,Jinshuai Song,Saihu Liao

doi:10.1038/s41467-020-20645-8

Abstract

Organocatalytic atom transfer radical polymerization (O-ATRP) is recently emerging as an appealing method for the synthesis of metal-free polymer materials with well-defined microstructures and architectures. However, the development of highly effective catalysts that can be employed at a practical low loading are still a challenging task. Herein, we introduce a catalyst design logic based on heteroatom-doping of polycyclic arenes, which leads to the discovery of oxygen-doped anthanthrene (ODA) as highly effective organic photoredox catalysts for O-ATRP. In comparison with known organocatalysts, ODAs feature strong visible-light absorption together with high molar extinction coefficient (ε455nm up to 23,950 M–1 cm–1), which allow for the establishment of a controlled polymerization under sunlight at low ppm levels of catalyst loading.

Highlights

Organocatalytic atom transfer radical polymerization (O-ATRP) is recently emerging as an appealing method for the synthesis of metal-free polymer materials with well-defined microstructures and architectures
Conventional ATRPs rely on transition metal catalysts [i.e., Cu(I), Ru(II)],3 which will result in transition metal contaminations in the final products, and raise concerns when applied to fields sensitive to metal contaminants.[4,5,6]
This absorption profile is in sharp contrast to that of the known photocatalysts such as 1–3, which possess a smaller conjugation in the core structure and absorption maximums appearing in the ultra-violet region (

Summary

Introduction

Organocatalytic atom transfer radical polymerization (O-ATRP) is recently emerging as an appealing method for the synthesis of metal-free polymer materials with well-defined microstructures and architectures. 1234567890():,; Since the discovery in the 1990s, atom transfer radical polymerization (ATRP) has evolved into one of the most versatile and utilized polymerization methods for the synthesis of polymer materials with well-defined structures and architectures, and widely employed in a variety of industrial applications including coatings, adhesives, cosmetics, inkjet printings, etc.[1,2,3] conventional ATRPs rely on transition metal catalysts [i.e., Cu(I), Ru(II)],3 which will result in transition metal contaminations in the final products, and raise concerns when applied to fields sensitive to metal contaminants.[4,5,6] considerable efforts have been dedicated to lowering catalyst loadings or removing residual metals since the initial discovery of ATRP.[5,6,7,8] Whereas, the recent emerging organocatalytic atom transfer radical polymerization (O-ATRP). We were thinking that heteroatom-doping[39,40] of small polycyclic arenes might be a feasible catalyst design logic for the O-ATRP photocatalyst development (Fig. 1b)

Methods

Results

Conclusion