Nanoparticle-Catalyzed Green Chemistry Synthesis of Polybenzoxazole

Abstract

Enabling catalysts to promote multistep chemical reactions in a tandem fashion is an exciting new direction for the green chemistry synthesis of materials. Nanoparticle (NP) catalysts are particularly well suited for tandem reactions due to the diverse surface-active sites they offer. Here, we report that AuPd alloy NPs, especially 3.7 nm Au 42 Pd 58 NPs, catalyze one-pot reactions of formic acid, diisopropoxy-dinitrobenzene, and terephthalaldehyde, yielding a very pure thermoplastic rigid-rod polymer, polybenzoxazole (PBO), with a molecular weight that is tunable from 5.8 to 19.1 kDa. The PBO films are more resistant to hydrolysis and possess thermal and mechanical properties that are superior to those of commercial PBO, Zylon. Cu NPs are also active in catalyzing tandem reactions to form PBO when formic acid is replaced with ammonia borane. Our work demonstrates a general approach to the green chemistry synthesis of rigid-rod polymers as lightweight structural materials for broad thermomechanical applications.

Cu2O nanoparticle-catalyzed tandem reactions for the synthesis of robust polybenzoxazole

“…26,42,43 The PA effect on PBO hydrolysis was also evidenced by a faster PBO property degradation in the boiled PA solution. 20,21 The PBO prepared by our method is intrinsically PA-free, which prompts us to study their stability against hydrolysis. A 10 μm thick PBO thin film was prepared by casting the NMP solution of the pre-PBO onto a glass plate and annealed at 350 °C.…”

“…19 These MPd alloy NPs were further applied to prepare the rigid-rod polymer polybenzoxazole (PBO) with much improved thermal and mechanical properties over the commercial PBO (Zylon®). 20,21 PBO belongs to a class of rigid-rod organic polymers with high tensile strength, stiffness, and thermal stability, and has shown great potential for ballistic fiber, anti-flame coating, and heat-resistant membrane applications. [22][23][24] It should be noted that the common method applied to prepare PBO requires the use of toxic/corrosive poly (phosphoric acid) and amine, 25 and the phosphoric acid residue embedded in the polymer structure is difficult to remove and can promote the hydrolysis of the benzoxazole-ring, compromising the thermal and mechanical stability of the polymer materials.…”

Controlling Multiple Active Sites on Pd−CeO2 for Sequential C−C Cross‐coupling and Alcohol Oxidation in One Reaction System

“…For example, zeolite was chosen to create acid sites for sequential condensation and hydrogenation, [8] and noble metals and their alloys were utilized to promote several multistep organic reactions in one reaction system. [9,10] Ceria (CeO 2 ), a representative reducible oxide, is a promising candidate for a multifunctional catalyst because CeO 2 not only has a unique Ce 3 + /Ce 4 + redox property [11,12] but also acts as a stable support for metal catalysts through strong interactions between metal and CeO 2 . [13][14][15][16] The redox-related catalytic properties of CeO 2 are closely related to its local surface structure, such as exposed facets and crystallite size.…”

Simultaneous Control of Formation and Growth of Asphaltene Solids and Wax Crystals Using Single-Walled Carbon Nanotubes: an Experimental Study under Real Oilfield Conditions

“…Due to the recent developments in nanoscience, nanotechnology has exhibited potential applications in different sections of the petroleum industry, such as exploration and production, drilling operations, enhanced oil recovery (EOR), and petrochemical refinery processes. − The potential of nanostructured materials is attributed to their unique properties, such as a large specific surface area, high mechanical and thermal stability, biocompatibility, or electroactivity. These tempting properties make some of them attractive as green chemicals for many situations. − Nanoparticles and nanofluids have gained great attention as an efficient alternative solution to traditional techniques for the mitigation of issues induced by asphaltene and wax precipitation and deposition. ,− …”