Hollow Periodic Mesoporous Organosilica Research Articles

A novel anti-scaling and protection coating based on hollow periodic mesoporous organosilica encapsulated with scale inhibitor

Scaling and corrosion are common issues in the petroleum industry that compromise production safety. Currently, organic coatings are considered the most effective method for scaling inhibition. This paper presents the synthesis of hollow periodic mesoporous organosilica (HPMO) nanocontainers with a high specific surface area and a uniform, ordered mesoporous structure, using a hard template method. The morphology of HPMO was controlled by adjusting the water-to-ethanol ratio and precursor amount. Characterization of HPMO morphology and structure was conducted using scanning electron microscope, transmission electron microscope, X-ray diffraction, and nitrogen adsorption-desorption analysis. To enhance loading capacity, HPMO was modified with 3-aminopropyl triethoxysilane, increasing the encapsulation of the scale inhibitor ethylenediamine tetramethylphosphonic acid (EDTMP) from 3.6 % to 13.8 %. The modified HPMO, loaded with the scale inhibitor, significantly improved the protective and anti-scaling properties of epoxy resin coatings. Compared with pure epoxy coatings, the scale inhibition rate of the composite coating increased by 42 % under static conditions and 90 % under dynamic conditions. The crystalline morphology of calcium carbonate scale was also influenced by the scale inhibitor; EDTMP promoted the formation of acicular aragonite and inhibited cuboid calcite growth in static conditions. In dynamic conditions, aragonite was not observed, and the calcite crystals were smaller than those formed in static solutions.

Cobalt and nitrogen co-doped hollow periodic mesoporous organosilica spheres activated by potassium chloride for selective oxidation of ethylbenzene.

Enhancing the exposure of metal active sites and maximizing metal atom utilization are critical challenges in heterogeneous catalysis. To solve these issues, heterogeneous catalysts are usually activated by chemicals. Herein, potassium chloride (KCl) was used as an activator to prepare cobalt-nitrogen co-doped (Co-Nx) hollow periodic mesoporous organosilica spheres (Co-Nx/HPMOs-KCl). Co-Nx/HPMOs-KCl showed outstanding catalytic activity for the selective oxidation of ethylbenzene to acetophenone, with a conversion of up to 94.0% for ethylbenzene and a high selectivity of 98.4% towards acetophenone. Additionally, Co-Nx/HPMOs-KCl maintained excellent catalytic performance for the oxidation of ethylbenzene after six cycles. The excellent performance of Co-Nx/HPMOs-KCl was attributed to the activation of KCl, which increased the specific surface area of the catalyst and thus facilitated the exposure of more metal active sites. After the removal of unstable metal species through further acid treatment, the remaining metal active sites were thus fully exposed and stably embedded in the framework of the hollow periodic mesoporous organosilica spheres (HMPOs). This work presents an efficient catalyst and offers new insights for the improvement of heterogeneous catalysts.

Cobalt and nitrogen co-modified hollow periodic mesoporous organosilica spheres for selective oxidation of aryl alkanes

Hollow periodic mesoporous organosilica spheres (HPMOs) have stimulated great research interest owing to its unique organic–inorganic hybrid skeleton. In this work, HPMOs were synthesized by hydrothermal method, and then cobalt and nitrogen co-doped carbon catalyst was prepared by using HPMOs as supports. The optimal catalyst (Co-Nx/HPMOs-D) performed excellent activity in the selective oxidation reaction of aryl alkanes, with the conversion of ethylbenzene up to 97.0% and the selectivity of acetophenone was 98.9%, which was attributed to the Co-Nx active species and the unique HPMOs supports. The unique amphiphilic property of Co-Nx/HPMOs-D could better facilitate the adsorption and diffusion of organic substrates in the aqueous phase. The addition of dicyandiamide not only enhanced the nitrogen content in the catalyst, but also promoted the conversion of pyrrolic-N to pyridinic-N during the pyrolysis process, thus strengthened the interaction between the substrate and cobalt and improved the stability of the catalyst. This work presented a green and environmentally friendly method for the preparation of HPMOs and a facile strategy to obtain high performance catalysts for selective oxidation of aryl alkanes.

Etched hollow periodic mesoporous organosilica with enlarged pore size for high-performance solid phase microextraction of polybrominated biphenyls

Hollow mesoporous silica has attracted increasing attention due to its outstanding characteristics such as low density, large void, mesoporous channel, and large specific surface area. Herein, a kind of etched hollow periodic mesoporous organosilica (EHPMOS) with enlarged mesopore size was successfully synthesized for high-performance solid phase microextraction (SPME). The etched silica material was prepared as a SPME fiber with uniform morphology, and the enrichment capacities for polybrominated biphenyls (PBBs) were systematically studied. In particular, the EHPMOS showed significant enrichment factors (158–9516) for PBBs. In addition, based on the home-made SPME fiber and gas chromatography-mass spectrometry (GC–MS), an ultra-sensitive analytical method was developed, with low limits of detection (0.11–0.32 ng·L-1), a wide linear range (1–1000 ng·L-1), and satisfactory reproducibility. And accurate quantifications of ultra-trace PBBs in environmental water sample were achieved.

Polyoxometalates Encapsulated into Hollow Periodic Mesoporous Organosilica as Nanoreactors for Extraction Oxidation Desulfurization

In this work, the highly active polyoxometalate (PW2Mo2) with Venturello structure and its corresponding catalyst were applied in catalytic desulfurization for the first time. PW2Mo2 as an active component was effectively encapsulated in hollow periodic mesoporous organosilica (HPMOS) to form the nanoreactor PW2Mo2@HPMOS, where the central cavity and mesoporous shell facilitate mass transfer and both provide a stable place to react with organic sulfides. Desulfurization test results show that the hollow nanoreactor PW2Mo2@HPMOS can almost remove four sulfides simultaneously from diesel in 2 h under mild conditions. Besides, the nanocatalyst PW2Mo2@HPMOS can be reused and recycled for at least seven consecutive tests without any noticeable loss in performance. With the rapid development of the economy, the massive use of sulfur-containing fuel has a huge impact on the global climate. After combustion of sulfur-containing fuel, the realized SOX is an important inducement of the formation of acid rain, and the realized sulfur particle is also a major source of haze. Therefore, removing sulfur compounds from fuel is an important issue that needs to be solved immediately.

Three birds with one stone: Contemporaneously boosting passive, active and self-healing properties for long-term anticorrosion coatings

Stimuli-responsive coatings can self-repair their own anticorrosion function in response to environmental changes, but they do not exhibit ideal long-term protective effect due to the lack of ability to regulate corrosive media, while this is vital to practical metal protection. Inspired by catalytic oxygen reduction, Cu-N center doped graphene oxide grafted with hollow periodic mesoporous organosilica nanocontainer (MBT@HPMO/Cu-GO) is synthesized via facile adsorption-pyrolysis strategy. Herein, introduced MBT@HPMO/Cu-GO is to simultaneously endow coatings with corrosive media shielding, active oxygen consumption and stimuli-responsive functions, thus “three birds with one stone”. The target catalyst exhibits excellent oxygen depletion performance (half-wave potential of 0.85 V) and is uniformly dispersed in the coating to construct steric hindrance against corrosive media. This dual effect allows composite coating to maintain the excellent anticorrosion performance over 60 days under oxygen environment. In addition, MBT@HPMO/Cu-GO can release inhibitor at corrosion sites in response to environment change when coating is damaged, so as to restore the protective ability of coating, with impedance increased from 2.4 × 107 Ω·cm2 to 1.5 × 108 Ω·cm2. Such multifunctional coating exploration overcomes the protective limitation of current self-healing coatings and sheds light on the design of intelligent long-term anticorrosion coatings.

Swellable hollow periodic mesoporous organosilica capsules with ultrahigh loading capacity for hydrophobic drugs.

As a new kind of drug carrier, practical applications of hollow periodic mesoporous organosilica (HPMO) have been greatly limited by their low loading capacity for hydrophobic drugs. In this work, we demonstrated the preparation of HPMO capsules with tunable shell thickness by using 1,2-bis(triethoxysilyl)ethane as the precursor. The capsules with thin shells and thus low Young's modulus showed excellent swellability to organic solvents containing hydrophobic drugs. As a result, hydrophobic drugs, i.e., paclitaxel (PTX) could be loaded into the hollow interior of the HPMO capsules with 4nm shell at an efficiency of ca. 120%. The as-prepared PTX-loaded HPMO capsules were dispersible in aqueous media and showed improved performance in killing cancer cells compared to free PTX.

Organic mesoporous silica with variable structures for pH-Stimulated antitumor drug delivery

Hollow (hollow periodic mesoporous organosilica, HPMO), core-shell (mSiO2@PMO), and bowl (nanobowl periodic mesoporous organosilica, BPMO) organic mesoporous silica nanoparticles were produced in this work. According to adsorption and desorption studies, all three have large pore diameters (2–10 nm), high specific surfaces (567–726 m2g-1), and large pore volumes (0.4–1.4 cm3g-1). After transporting the antitumor pharmaceutical doxorubicin (DOX) and ZnO-controlled pH stimulation response modification, the obtained DOX@PMOs@ZnO has a high drug loading rate (17–37%, with the largest drug loading capacity up to 378 μg/mg). Cell uptake and apoptosis tests revealed that the three morphologies of DOX@PMOs@ZnO had high cellular uptake and inhibitory effects. These results showed that the DOX@PMOs@ZnO preparation may be beneficial for tumor-targeted therapy. More importantly, when three unique morphologies of DOX@PMOs@ZnO were analyzed in terms of drug loading, cell uptake, and apoptosis, the findings showed that the hollow structure of DOX@HPMO@ZnO and the bowl-like structure of DOX@BPMO@ZnO had more substantial impacts in all areas.

Venturello Structure Polyoxometalates Encapsulated into Hollow Periodic Mesoporous Organosilica as Nanoreactors for Extraction Oxidation Desulfurization

Venturello Structure Polyoxometalates Encapsulated into Hollow Periodic Mesoporous Organosilica as Nanoreactors for Extraction Oxidation Desulfurization

Unexpected phenomenon in a conventional system: synthesis of raspberry-like hollow periodic mesoporous organosilica with controlled structure in one continuous step

We put forward a facile method to fabricate raspberry-like hollow PMO with tunable morphology, derived from an interesting phenomenon in preparing conventional PMO.

Amine-promoted Ru1/Fe3O4 encapsulated in hollow periodic mesoporousorganosilica sphere as a highly selective and stable catalyst for aqueous levulinic acid hydrogenation

It is of great importance to develop selective and stable metal catalysts for the aqueous levulinic acid hydrogenation, yet challenging. Herein, we report a yolk-structured sing atom catalyst (SAC) with amine-modified Ru1/Fe3O4 core and periodic mesoporousorganosilica (PMO) shell, synthesized by a core–shell dual stabilization strategy. The Ru single atoms (0.76 wt%) are inserted into the oxygen vacancies of spheric Fe3O4, and stabilized by the amine groups from 1,6-hexanediamine. The hollow PMO sphere is hydrophobic, that affords a strong barrier for interior Ru1/Fe3O4 core, and the shell mesopore (4.2 nm) along with the cavity enhances the porosity of the resultant catalyst. As expected, the amine-promoted Ru1/Fe3O4 core in the hollow PMO shell (denoted as N-Ru1/Fe3O4@void@PMO), proves to be highly selective and stable for the aqueous levulinic acid (LA) hydrogenation under harsh conditions (pH ≈ 1), giving γ-valerolactone (GVL), a biomass-derived platform molecule with wide applications in the preparation of renewable chemicals and liquid transportation fuels. The elaborately fabricated catalyst is highly efficient, delivering 98.9% of selectivity to GVL and 99.0% of LA conversion in acidic water. And a high turnover frequency of 1084 h−1 is achieved and this catalyst can be cycled 7 times without apparent drop of GVL yield and LA conversion. The amine-stabilized Ru single sites, acid-resistant Fe3O4 circled by the hydrophobic shell, and the enhanced porosity of catalyst, are responsible for the excellent catalytic performance of N-Ru1/Fe3O4@void@PMO in acidic water.

Inhibitor-self-gated stimuli-responsive anticorrosion system based on π-π stacking

Most of existing nanocontainers suffer from tedious, complicated and unsustainable assembly process which restricts their application in corrosion protection as smart inhibitor carriers. In this study, we adopted the framework-hybridization approach to prepare a smart anticorrosion system (MBT@Ph-HPMO), with MBT inhibitor as cargo and phenylene-bridged hollow periodic mesoporous organosilica (Ph-HPMO) as nanocontainer. Results reveal that the π-π stacking between MBT and framework of Ph-HPMO serves as nature valve, which is supplemented by the molecular dynamic simulation. The encapsulated inhibitor was loaded into Ph-HPMO at neutral pH, demonstrating fast release in acidic environment. On-demand release of inhibitors from MBT@Ph-HPMO contributed to achieving in situ active corrosion protection. Anticorrosion performance of MBT@Ph-HPMO for copper alloy was evaluated in 3.5 wt% NaCl solution for a period of 30 days. The alloy exhibited the slightest corrosion damage in the corrosion medium with the addition of 0.24 wt% MBT@Ph-HPMO. This facile and versatile strategy will have broad applications in new class of nanocontainers fabrication and open up a new prospect for active corrosion protection.

Organosilica: Mesoporous Organosilica Hollow Nanoparticles: Synthesis and Applications (Adv. Mater. 38/2019)

In article number 1707612, Wei Li, Guangming Lu, Dongyuan Zhao, and co-workers review advances in the synthesis of hollow periodic mesoporous organosilica (PMO) nanoparticles with various organic moieties. The synthetic strategies, smart hollow architectures, and typical applications for hollow PMOs are systemically discussed.

Deformable Hollow Periodic Mesoporous Organosilica Nanocapsules for Significantly Improved Cellular Uptake.

Mesoporous solids have been widely used in various biomedical areas such as drug delivery and tumor therapy. Although deformability has been recognized as a prime important characteristic influencing cellular uptake, the synthesis of deformable mesoporous solids is still a great challenge. Herein, deformable thioether-, benzene-, and ethane-bridged hollow periodic mesoporous organosilica (HPMO) nanocapsules have successfully been synthesized for the first time by a preferential etching approach. The prepared HPMO nanocapsules possess uniform diameters (240-310 nm), high surface areas (up to 878 m2·g-1), well-defined mesopores (2.6-3.2 nm), and large pore volumes (0.33-0.75 m3·g-1). Most importantly, the HPMO nanocapsules simultaneously have large hollow cavities (164-270 nm), thin shell thicknesses (20-38 nm), and abundant organic moiety in the shells, which endow a lower Young's modulus (EY) of 3.95 MPa than that of solid PMO nanoparticles (251 MPa). The HPMOs with low EY are intrinsically flexible and deformable in the solution, which has been well-characterized by liquid cell electron microscopy. More interestingly, it is found that the deformable HPMOs can easily enter into human breast cancer MCF-7 cells via a spherical-to-oval morphology change, resulting in a 26-fold enhancement in cellular uptake (43.1% cells internalized with nanocapsules versus 1.65% cells with solid counterparts). The deformable HPMO nanocapsules were further loaded with anticancer drug doxorubicin (DOX), which shows high killing effects for MCF-7 cells, demonstrating the promise for biomedical applications.

Controllable synthesis of hollow periodic mesoporous organosilica spheres with radial mesochannels and their degradable behavior

Hollow periodic mesoporous organosilica spheres with radial mesochannels have been efficiently and controllably synthesized only through introducing a pre-hydrolysis process.

A one-step method for pore expansion and enlargement of hollow cavity of hollow periodic mesoporous organosilica spheres

In this study, a facile one-step method combining the pore expansion and the enlargement of the hollow cavity of hollow periodic mesoporous organosilica spheres (HPMOSs) into one step was proposed. Moreover, the whole process for the formation just needs 1 h and involves reaction just under normal pressure and temperature. We further investigate the influence of different expanders and the amount of expanders on pore size and hollow cavity size. The obtained HPMOSs using tridecane as expander possess excellent properties, including good spherical morphology, large hollow structures, radially oriented mesochannels (3.44 nm), uniform particle size (115 nm), high BET surface area (1298 m2/g), and large pore volume (1.96 cm3/g). In addition, the hollow cavity size and the mesoporous size can be controlled via the modulation of tridecane amount. This method also provides a basis for synthesizing both large pore and the hollow cavity of functionalized, monodispersed HPMOSs.

A facile “polystyrene-dissolving” strategy to hollow periodic mesoporous organosilica with flexible structure-tailorability

A facile “template dissolving” strategy has been developed for the fabrication of hollow periodic mesoporous organosilica (HPMO) particles with perpendicularly ordered mesopores, where polystyrene (PS) is used as sacrifice template for the generation of hollow cavity. Systematic characterizations including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and N2 adsorption/desorption analysis clearly reveal that the HPMO particles have an excellent monodispersity with a high specific surface area of 1246.7 m2 g−1, large pore volume of 1.38 cm3 g−1 and uniformly ordered mesopores of 2.48 nm. The pre-encapsulation of a core into PS (SiO2, Fe3O4@SiO2) results in a yolk-shell (Y-S) particle with high tunable shell thickness (30–60 nm) and cavity size (230–450 nm). The magnetically recyclable Fe3O4-YS-PMO was further utilized to adsorb 2, 4-dichlorophenol (2, 4-DCP) and the controlled release of camptothecin (CPT). Up to 81 mg of CPT was loaded per gram of the Fe3O4-YS-PMO particles, followed with a continuously release of 76% within 5 days.

Synergistic Chemo-Photothermal Therapy of Breast Cancer by Mesenchymal Stem Cell-Encapsulated Yolk-Shell GNR@HPMO-PTX Nanospheres.

Mesenchymal stem cells (MSCs) have attracted increasing attention as vehicles for cancer treatment. Herein, MSC-based synergistic oncotherapy strategy is presented for the first time. To achieve this goal, yolk-shell structured gold nanorod embedded hollow periodic mesoporous organosilica nanospheres (GNR@HPMOs) with high paclitaxel (PTX) loading capability and excellent photothermal transfer ability upon near-infrared (NIR) light irradiation are first prepared. Cytotoxicity and migration assays show that the viability and tumor-homing capability of MSCs are well-retained after internalization of high content of PTX loaded GNR@HPMOs (denoted as GNR@HPMOs-PTX). In vitro experiments show the GNR@HPMOs-PTX loaded MSCs (GNR@HPMOs-PTX@MSCs) possess synergistic chemo-photothermal killing effects for breast cancer cells. Also, photoacoustic imaging shows that the MSCs can improve dispersion and distribution in tumor tissue for GNR@HPMOs-PTX after intratumoral injection. In vivo experiments in breast cancer model of nude mice further demonstrate that the GNR@HPMOs-PTX@MSCs significantly inhibit tumor growth, suggesting their great potential for synergistic therapy of cancer.

Hollow periodic mesoporous organosilica nanospheres by a facile emulsion approach

Periodic mesoporous organosilicas (PMOs) with homogeneously incorporated organic groups, highly ordered mesopores, and controllable morphology have attracted increasing attention. In this work, one-step emulsion approach for preparation of hollow periodic mesoporous organosilica (HPMO) nanospheres has been established. The method is intrinsically simple and does not require any sacrificial templates, corrosive and toxic etching agents. The obtained HPMO nanospheres have high surface area (∼950m2g−1), accessible ordered mesochannels (∼3.4nm), large pore volume (∼3.96cm3g−1), high condensation degree (77%), and diameter (∼560nm), hollow chamber size (∼400nm), and shell thickness (∼80nm). Furthermore, cytotoxicity show the cell viability is higher than 86% after incubating with the HPMO nanospheres at a concentration of up to 1200μgmL−1 for 24h. The hemolysis of HPMO nanospheres is lower than 1.1% at concentrations ranging from 10 to 2000μgmL−1. The lower hemolysis and cytotoxicity make the HPMO nanospheres great promise for future biomedical applications.

A one-step synthesis of hollow periodic mesoporous organosilica spheres with radially oriented mesochannels.

A simple and effective one-step method is proposed for the fabrication of hollow periodic mesoporous organosilica spheres (HPMOSs). The obtained HPMOSs possess well-defined spherical morphology, uniform and tunable particle size, adjustable hollow void structure, and radially oriented mesochannels in their shells.