In this study,p orphyrinic zirconium (Zr) MOFs were investigated as heterogeneous photocatalysts for photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of various monomers under abroad range of wavelengths,producing polymers with high monomer conversions,n arrowm olecular weight distributions,l ow dispersity and good chain-end fidelity. Screening of various porphyrinic Zr-MOFs (Zn) containing Zn-metalled porphyrinic ligands demonstrated that MOF-525 (Zn) with the smallest sizeh ad the best photocatalytic activity in PET-RAFT polymerization, due to enhanced dispersion and light penetration. Oxygen tolerance and temporal control were also demonstrated during MOF catalysed PET-RAFT.Results suggested that the polymerization rates were significantly affected by changing the sizea nd surface area of MOFs,a nd the heterogeneous MOF photocatalysts could be easily separated and recycled for up to five independent PET-RAFT polymerizations without an obvious decrease in efficiency. Finally,t he MOF photocatalysts were utilized to create threedimensional polymeric objects with high resolution via visible light mediated stereolithography in an open-air environment.

A series of samples with the precursor’s molar ratio of {KMn8O16}/{CuFe2O4} = 0, 0.008, 0.010, 0.016, and 0.020 were successfully synthesized for selective catalytic reduction of NO by CO. The physicochemical properties of all samples were studied in detail by combining the means of X-ray photoelectron spectroscopy, H2-temperature-programmed reduction, scanning electron microscopy mapping, X-ray diffraction (XRD), N2 physisorption (Brunauer–Emmett–Teller), NO + CO model reaction, and in situ Fourier transform infrared spectroscopy techniques. The results show that three phases of γ-Fe2O3, CuFe2O4, and CuO, which have strong synergistic interaction, coexist in this catalyst system, and different phases play a leading role in different temperature ranges. Mn species are highly dispersed in the three-phase coexisting system in the form of Mn2+, Mn3+, and Mn4+. Because of the strong interaction between Mn2+ and Fe species, a small amount of Cu2+ precipitates from CuFe2O4 and grows along the CuO(110) plane, which has better catalytic performance. Mn3+ can inhibit the conversion of γ-Fe2O3 to α-Fe2O3 at high temperature and then increases the high-temperature activity. The synergistic effect between Mn4+ and the surfaces of three phases generates active oxygen species Cu2+–O–Mn4+ and Mn4+–O–Fe3+, which can be more easily reduced to some synergistic oxygen vacancies during the reaction. Furthermore, the formed synergistic oxygen vacancies can promote the dissociation of NO and are also propitious to the transfer of oxygen species. All of these factors make the appropriate manganese-modified three-phase coexisting system have better catalytic activity than the manganese-free catalyst, making NO conversion rate reach 100% at around 250 °C and maintain to 1000 °C. Combining comprehensive analysis of various characterization results and in situ infrared as well as XRD results in the equilibrium state, a new possible NO + CO model reaction mechanism was temporarily proposed to further understand the catalytic processes.

Although 3D printing allows the macroscopic structure of objects to be easily controlled, controlling the nanostructure of 3D printed materials has rarely been reported. Herein, we report an efficient and versatile process for fabricating 3D printed materials with controlled nanoscale structural features. This approach uses resins containing macromolecular chain transfer agents (macroCTAs) which microphase separate during the photoinduced 3D printing process to form nanostructured materials. By varying the chain length of the macroCTA, we demonstrate a high level of control over the microphase separation behavior, resulting in materials with controllable nanoscale sizes and morphologies. Importantly, the bulk mechanical properties of 3D printed objects are correlated with their morphologies; transitioning from discrete globular to interpenetrating domains results in a marked improvement in mechanical performance, which is ascribed to the increased interfacial interaction between soft and hard domains. Overall, the findings of this work enable the simplified production of materials with tightly controllable nanostructures for broad potential applications.

Ultrathin porphyrinic 2D MOFs, ZnTCPP nanosheets (TCPP: 5,10,15, porphyrin) were employed as heterogeneous photocatalysts to activate PET-RAFT polymerization under various wavelengths ranging from violet to orange light. High polymerization rates, oxygen tolerance, and precise temporal control were achieved. The polymers showed narrow molecular weight distributions and good chain-end fidelity. The 2D ZnTCPP nanosheets were applied as photocatalysts in stereolithographic 3D printing in an open-air environment under blue light to yield well-defined 3D printed objects. Apart from providing an efficient catalytic system, 2D ZnTCPP nanosheets reinforced the mechanical properties of the 3D printed materials. The presence of ZnTCPP embedded in the materials conferred effective antimicrobial activity under visible light by production of singlet oxygen, affording 98 % and 93 % anti-bacterial efficiency against Gram-positive and Gram-negative bacteria, respectively.

Nanostructured polymeric materials play important roles in many advanced applications, however, controlling the morphologies of polymeric thermosets remains a challenge. This work uses multi‐arm macroCTAs to mediate polymerization‐induced microphase separation (PIMS) and prepare nanostructured materials via photoinduced 3D printing. The characteristic length scale of microphase‐separated domains is determined by the macroCTA arm length, while nanoscale morphologies are controlled by the macroCTA architecture. Specifically, using 2‐ and 4‐ arm macroCTAs provides materials with different morphologies compared to analogous monofunctional linear macroCTAs at similar compositions. The mechanical properties of these nanostructured thermosets can also be tuned while maintaining the desired morphologies. Using multi‐arm macroCTAs can thus broaden the scope of accessible nanostructures for extended applications, including the fabrication of actuators and potential drug delivery devices.

Reversible addition-fragmentation chain-transfer (RAFT) polymerization has been widely exploited to produce homogeneous and living polymer networks for advanced material design. In this work, we incorporate silica nanoparticles (SNPs) into a...

The application of reversible addition–fragmentation chain-transfer (RAFT) agents in stereolithographic 3D printing has been seldom reported due to their tendency to reduce polymerization rates.

Several industrial- and research-type composite solid propellants containing different nano metric metal oxide catalysts (Fe2O3, Co3O4, CuO, and PbO) with similar nominal composition, were prepared and experimentally analyzed. The effects of different nano-sized metal oxide catalysts on the rheological properties and hazardous properties were investigated. The strand burning rate and the associated combustion flame structure of composite propellants were determined. The results show that the nano-sized metal oxide powders can be sufficiently dispersed in hydroxyl terminated polybutadiene binder. The propellant formulations containing nano metal oxide particles are sensitive to impact and friction except for the base propellant without nano-sized powders, which is less sensitive to friction as compared to the other compositions. The nano-sized metal oxide additives can affect the combustion behavior and increase the burning rate of propellants compared with the reference propellant composition