3-Hydroxythiophenol-Formaldehyde Resin Microspheres Modulated by Sulfhydryl Groups for Highly Efficient Photocatalytic Synthesis of H2O2

Resorcinol-formaldehyde (RF) resin represents a promising visible-light responding photocatalyst for oxygen reduction reaction (ORR) toward H2O2 production. However, its photocatalytic ORR activity toward H2O2 generation is still unsatisfied for practical application. Herein, 3-hydroxythiophenol-formaldehyde (3-HTPF) resin microspheres synthesized through polycondensation reaction between 3-HTP and formaldehyde at room temperature and subsequent hydrothermal treatment exhibit enhanced photocatalytic ORR activity is reported. The experimental results show that the partial substitution of hydroxy group (─OH) by sulfhydryl one (─SH) through using 3-HTP to replace resorcinol could slow the rates of nucleation and growth of the resin particles and lead to strongly π-stacked architecture in 3-HTPF. The introduction of ─SH group can also improve adsorption ability of 3-HTPF to O2 molecules and enhance ORR catalytic activity of the photocatalysts. Stronger built-in electric field, better adsorption ability to O2 molecules, and increased surface catalytic activity collectively boost photocatalytic activity of 3-HTPF microspheres. As a result, H2O2 production rate of 2010 µm h-1 is achieved over 3-HTPF microspheres at 273 K, which is 3.4 times larger than that obtained using RF submicrospheres (591 µm h-1). The rational substituent group modulation provides a new strategy for designing polymeric photocatalysts at the molecular level toward high-efficiency artificial photosynthesis.

Polymeric Bowl-Shaped Nanoparticles: Hollow Structures with a Large Opening on the Surface

Polymeric bowl-shaped nanoparticles (BNPs) are anisotropic hollow structures with large openings on the surface, which have shown advantages such as high specific area and efficient encapsulation, delivery and release of large-sized cargoes on demand compared to solid nanoparticles or closed hollow structures. Several strategies have been developed to prepare BNPs based on either template or template-free methods. For instance, despite the widely used self-assembly strategy, alternative methods including emulsion polymerization, swelling and freeze-drying of polymeric spheres, and template-assisted approaches have also been developed. It is attractive but still challenging to fabricate BNPs due to their unique structural features. However, there is still no comprehensive summary of BNPs up to now, which significantly hinders the further development of this field. In this review, the recent progress of BNPs will be highlighted from the perspectives of design strategies, preparation methods, formation mechanisms, and emerging applications. Moreover, the future perspectives of BNPs will also be proposed.

Autofluorescent Polymers: 1 H,1 H,2 H,2 H-Perfluoro-1-decanol Grafted Poly(styrene- b-acrylic acid) Block Copolymers without Conventional Fluorophore

Recently, although several unconventional luminescent polymers have been synthesized, it still remains a significant challenge to prepare various new fluorescent polymers by functionalization of nonfluorescent polymers. A nonfluorescent 1 H,1 H,2 H,2 H-perfluoro-1-decanol grafted to nonfluorescent polystyrene- b-poly(acrylic acid) block copolymers through simply esterification reaction can exhibit strong blue emission. On the basis of control experiments and theoretical simulation, we have proposed that the luminescence stems from interchain n → π* interaction between the lone pair (n) of hydroxyl O atoms of carboxyl units and empty π* orbital of ester carbonyl unit. In addition, the fluorescent polymers are successfully employed for fluorescence imaging in living HeLa cell.