Structure and Morphology Engineering of Hollow Conjugated Microporous Photocatalysts to Boost Photo-Controlled Polymerization at Near-Infrared Wavelengths
Xue Li, Yuan Huang, Min Jian, Xi Juan Zhang, Tao Cai
Abstract
Structure and morphology engineering of conjugated microporous polymers has been considered a promising strategy in the field of photopolymerization as it has the potential to promote catalytic efficiency and address challenges in product contamination. Herein, hollow conjugated microporous photocatalysts (S- h PorIPN MSs) were constructed by Sonogashira–Hagihara polycondensation on the surface of SiO 2 templates, followed by removal of the SiO 2 inner cores and sulfonation of the conjugated shells. Upon the introduction of cyano and sulfonic acid substituents, S- h PorIPN MSs were utilized as an excellent heterogeneous photocatalyst to trigger aqueous RAFT polymerization by a 740 nm near-infrared (NIR) light, affording the preparation of diverse polymers with predictable molecular weight and narrow dispersity. The enhanced penetration capabilities provided by NIR wavelengths allowed the photopolymerization to be conducted through synthetic and biological barriers at faster polymerization rates in a non-degassed system. Furthermore, high end-group integrity, excellent monomer/chain transfer agent adaptation, and reliable reusability were highlighted on the S- h PorIPN MSs being applied as photocatalysts for NIR-light-driven polymerization. Taking advantage of the higher surface-area-to-volume ratio and more accessible active sites of S- h PorIPN MSs, we presented the first metal-free heterogeneous catalyst system capable of achieving faster polymerization rates through light-proof barriers for aqueous RAFT polymerization.