Polyhedral Oligomeric Silsesquioxane Research Articles

Redox‐Active Organic Molecules Supported by Polyhedral Oligomeric Silsesquioxane

AbstractOrganic redox molecules have attracted considerable attention because of their abundant availability and excellent design flexibility. For practical applications, these molecules must be anchored onto scaffolds such as polymers to prevent crystallization and elution into the electrolyte. In this study, we explore the use of polyhedral oligomeric silsesquioxane (POSS) derivatives as scaffolds for anthraquinone (AQ) and hydroquinone. We investigated the cage structure of POSS and the number of redox units incorporated. Notably, a corner‐opened POSS (CO‐POSS) variant with three AQ units exhibited reversible redox behavior under neutral, acidic, and basic conditions. Furthermore, we examined the air‐battery performance of AQ‐modified CO‐POSS as an anode‐active material.

Silsesquioxane Cages under Solvent Regimen: The Influence of the Solvent on the Hydrolysis and Condensation of Alkoxysilane.

This study investigates the formation mechanisms of oligomeric phenyl silanols, focusing on polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane (DDSQ) derivatives. Combining literature reports and crystal structures of solvated derivatives obtained in our laboratory, we show that the solvent choice significantly influences their structures. POSS-based silanols prefer aprotic solvents like THF, preserving dimerization, while double-deckers form stable architectures in protic solvents like isopropanol. This discrepancy arises from different stabilization mechanisms. Our findings enhance our understanding of hydrolytic condensation involving trimethoxyphenylsilane and suggest aprotic solvents for efficient reactions with POSS-based silanols.

Exploring drug release performance of hollow‐structured CS/SA/POSS composite gel spheres employing hydrophilic polymerizable AS‐POSS as crosslinker

AbstractThis study prepares a series of hollow‐structured CS/SA/POSS composite gel spheres with a diameter of ~2.5 mm by using hydrophilic Janus‐type polyhedral oligomeric silsesquioxane (AS‐POSS) as a crosslinking agent in combination with sodium alginate and chitosan via electrostatic adsorption/free radical polymerization. As the content of POSS increases, the wall thickness of the gel spheres also increases from 20 to 30 μm, leading to a more compact and smooth wall structure in the polymerized CS/SA/POSS composite gel spheres. Additionally, the introduction and polymerization of POSS significantly enhance the stability, drug loading rate, and entrapment rate of the gel spheres, providing them with improved drug release capabilities. For hydrophilic drug doxorubicin, the loading rate and encapsulation rate reach 41.2% and 79.9%, respectively, while for the hydrophobic drug ibuprofen, they are 14.7% and 76.3%. Compared to some previously reported drug‐loaded gel materials, the gels prepared in this study demonstrate relatively higher drug loading performance. Thus, these hollow‐structured CS/SA/POSS composite gel spheres hold promise as innovative drug carriers in the biomedical field.

AgNPs loaded adenine-modified chitosan composite POSS-PEG hybrid hydrogel with enhanced antibacterial and cell proliferation properties for promotion of infected wound healing

Wound healing is a dynamic and complex process, it's urgent to develop new wound dressings with excellent performance to promote wound healing at the different stages. Here, a novel composite hydrogel dressing composed by silver nanoparticles (AgNPs) impregnated adenine-modified chitosan (CS-A) and octafunctionalized polyhedral oligomeric silsesquioxane (POSS) of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) solution was presented to solve the problem of wound infection. Modification of chitosan with adenine, not only can improve the water solubility of chitosan, but also introduce bioactive substances to promote cell proliferation. CS-A and POSS-PEG-CHO were cross-linked by Schiff-base reaction to form the injectable self-healing hydrogel. On this basis, AgNPs were added into the hydrogel, which endows the hydrogel with better antibacterial activity. Moreover, this kind of hydrogel exhibits excellent cell proliferation properties. Studies demonstrated that the hydrogel can significantly accelerate the closure of infected wounds. The histological analysis and immunofluorescence staining demonstrated that the wounds treated with the composite hydrogel exhibited fewer inflammatory cells, more collagen deposition and angiogenesis, faster regeneration of epithelial tissue. Above all, adenine-modified chitosan composite hydrogel with AgNPs loaded was considered as a dressing material with great application potential for promoting the healing of infected wounds.

Directional self-assembly of octavinyl polyhedral oligomeric silsesquioxane on the surface of melamine sponge: Establishing hydrophobic surfaces to improve oil–water separation performance

The continuous increase in industrial organic pollutants has seriously contaminated the natural environment, posing a threat to natural ecosystems and human survival. The preparation of hydrophobic materials with corrosion resistance is crucial for the efficient treatment of emulsified oil–water mixtures in industrial wastewater.Octavinyl polyhedral oligomeric silsesquioxane-coated melamine foam (OV-POSS@MF), possessing hydrophobic properties, was synthesized through a two-step process: initially, a sulfhydryl layer was built up on the surface of the melamine foam, followed by the subsequent assembly of octavinyl POSS onto the melamine foam’s surface via a free radical polymerization reaction between sulfhydryl groups and vinyl moieties. OV-POSS@MF achieves a static water contact angle of 141°, demonstrating its pronounced hydrophobic nature. Moreover, the corrosion resistance, adsorption capacity, oil–water separation efficiency, deformation resistance, and flame retardancy of OV-POSS@MF were thoroughly examined. The results indicate that OV-POSS@MF exhibits strong corrosion resistance and maintains good hydrophobicity even after prolonged exposure to highly acidic and alkaline conditions. Notably, OV-POSS@MF possesses the capability to efficiently and rapidly separate emulsified oil–water mixtures. Furthermore, it retains excellent hydrophobicity even after undergoing up to 100 consecutive compressions or distortions, highlighting its remarkable mechanical resilience. Additionally, OV-POSS@MF demonstrates superior flame retardant properties compared to unmodified melamine foam (MF).

Solvent-Mediated Chiral Self-Assembly of Nanosized π-Conjugated Polyhedral Oligomeric Silsesquioxane toward Full Spectrum Luminescence

Solvent-Mediated Chiral Self-Assembly of Nanosized π-Conjugated Polyhedral Oligomeric Silsesquioxane toward Full Spectrum Luminescence

Correction to: Poly(lactic acid)/poly(butylene adipate-co-terephthalate) films reinforced with polyhedral oligomeric silsesquioxane nanoparticles: a morphological, mechanical, and thermal study

Correction to: Poly(lactic acid)/poly(butylene adipate-co-terephthalate) films reinforced with polyhedral oligomeric silsesquioxane nanoparticles: a morphological, mechanical, and thermal study

Polyhedral Oligomeric Sesquioxane Cross-Linked Chitosan-Based Multi-Effective Aerogel Preparation and Its Water-Driven Recovery Mechanism.

The use of environmentally friendly and non-toxic biomass-based interfacial solar water evaporators has been widely reported as a method for water purification in recent years. However, the poor stability of the water transport layer made from biomass materials and its susceptibility to deformation when exposed to harsh environments limit its practical application. To address this issue, water-driven recovery aerogel (PCS) was prepared by cross-linking epoxy-based polyhedral oligomeric silsesquioxane (EP-POSS) epoxy groups with chitosan (CS) amino groups. The results demonstrate that PCS exhibits excellent water-driven recovery performance, regaining its original volume within a very short time (1.9 s) after strong compression (ε > 80%). Moreover, PCS has a water absorption rate of 2.67 mm s-1 and exhibits an excellent water absorption capacity of 22.09 g g-1 even after ten cycles of absorption-removal. Furthermore, a photothermal evaporator (PCH) was prepared by loading the top layer with hydrothermally reacted tannins (HAs) and Zn2+ complexes. The results indicate that PCH achieves an impressive evaporation rate of 1.89 kg m-2 h-1 under one sun illumination. Additionally, due to the antimicrobial properties of Zn2+, PCH shows inhibitory effects against Staphylococcus aureus and Escherichia coli, thereby extending the application of solar water evaporators to include antimicrobial purification in natural waters.

Exploration of Molecular Nanoparticles as Soft Structural Materials and Their Structure-Property Relationship.

The search for alternative chemical systems other than polymers with chain topologies for soft structural materials raises general interests in fundamental materials and chemical sciences. It is also appealing from an engineering perspective for the urgent need to resolve the typical trade-offs of polymer systems. Herein, a subnanometer molecular cluster, polyhedral oligomeric silsesquioxanes, is assembled into molecular nanoparticles (MNPs) with star topology. Broadly tunable viscoelasticity can be realized by fine-tuning the MNPs' deformability. Being analogous to polymeric systems, the hierarchical structural relaxation dynamics can be observed, and their relaxation time and temperature dependence are dominated by the linker flexibilities. This not only provides microscopic understanding on MNP's unique viscoelasticity but also offers enormous opportunities for modulating their mechanical properties via linker engineering. Our work proves the possibility of applying structural units with particle topologies for the design of soft structural materials.

Polyurea/Aminopropyl Isobutyl Polyhedral Oligomeric Silsesquioxane-Functionalized Graphene Nanoplatelet Nanocomposites for Force Protection Applications.

Herein, the development of new nanocomposite systems is reported based on one-part polyurea (PU) and aminopropyl isobutyl polyhedral oligomeric silsesquioxane (POSS)-functionalized graphene nanoplatelets (GNP-POSS) as compatible nanoreinforcements with the PU resin. GNP-POSS was effectively synthesized via a two-step synthesis protocol, including ultrasonication-assisted reaction and precipitation, and carefully characterized with respect to its chemical and crystalline structure, morphology, and thermal stability. FTIR and XPS spectroscopy analyses revealed that POSS interacts with the residual oxygen moieties of the GNPs through both covalent and noncovalent bonding. The X-ray diffraction pattern of GNP-POSS further revealed that the crystallinity of the GNPs was not altered after their functionalization with POSS. GNP-POSS was successfully incorporated in PU at contents of 1, 3, 5, and 10 wt % to yield PU/GNP-POSS nanocomposite films. An ATR-FTIR analysis of these films confirmed the presence of strong interfacial interactions between the urea groups of PU and the GNP-POSS functionalities. Moreover, the PU/GNP-POSS nanocomposite films exhibited enhanced thermal stability and mechanical properties compared to those of the neat PU film. The quasi-static tensile testing of the PU/GNP-POSS samples revealed remarkable enhancements in the tensile strength (from 7.9 for the neat PU to 25.1 MPa for PU/GNP-POSS) and Young's modulus (238-617 MPa), while elongation at break and toughness also showed 14 and 125% improvements, respectively. Finally, the effects of GNP-POSS content on the morphological, quasistatic tensile, and high-strain-rate dynamic behavior of the PU/GNP-POSS nanocomposite films were also investigated. Overall, the tests performed using a split-Hopkinson pressure bar setup revealed a large increase in the film strength (from 147.6 for the neat PU film to 199 MPa for the PU/GNP-POSS film) and a marginal increase in the energy density of the film (38.1-40.8 kJ/m3). These findings support the suitability of the PU/GNP-POSS nanocomposite films for force protection applications.

Photoresponsive Viscoelasticity of the Granular Materials of Azobenzene-Bearing Molecular Nanoparticles.

The large sizes of granular particles lead to their slow diffusive dynamics and significant interparticle friction, bringing enormous difficulty to tune the mechanical properties and processability of the granular materials (GMs). Herein, 1 nm polyhedral oligomeric silsesquioxane (POSS) particles functionalized with azobenzene are designed as structural units, and the obtained GMs show unique photoswitchable viscoelasticity. The azobenzene group can undergo a reversible trans-cis conformation switch while the π-π stacking among the azobenzene fragments is only favored by the trans-conformation due to molecular geometrical requirements. The POSS units from neighboring assemblies close pack to form microdomains, and the POSS is under confinement by both the supramolecular bonding and the other POSS in the microdomains. The simultaneous breaking of the two types of confinement is difficult and, therefore, the free diffusion of POSS is hindered, leading to the elasticity of the GMs of trans-POSS. For cis-POSS, the interparticle supramolecular interaction is weak and the POSS unit can undergo free diffusion, contributing to their high flowability at room temperature. The photoswitching viscoelasticity of GMs is further used for self-healing and photoswitchable adhesion. This work paves new pathways for the regulation of material viscoelasticity and the design of GM-based smart materials.

Organic-Inorganic Hybrid Materials: Tailoring Carbon Dioxide-Based Polycarbonate with POSS-SH Crosslinking.

A novel functional polycarbonate (PAGC), characterized by the presence of double bonds within its side chain, was successfully synthesized through a ternary copolymerization of propylene oxide (PO), allyl glycidyl ether (AGE), and carbon dioxide (CO2). Polyhedral oligomeric silsesquioxanes octamercaptopropyl (POSS-SH) was employed as a crosslinking agent, contributing to the formation of organic-inorganic hybrid materials. This incorporation was facilitated through thiol-ene click reactions, enabling effective interactions between the POSS molecules and the double bonds in the side chains of the polycarbonate. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed a homogeneous distribution of silicon (Si) and sulfur (S) in the polycarbonate matrix. The thiol-ene click reaction between POSS-SH and the polycarbonate led to a micro-crosslinked structure. This enhancement significantly increased the tensile strength of the polycarbonate to 42 MPa, a notable improvement over traditional poly (propylene carbonate) (PPC). Moreover, the cross-linked structure exhibited enhanced solvent resistance, expanding the potential applications of these polycarbonates in various plastic materials.

Development of a novel hybrid POSS nanocomposite for the detection of parabens in environmental samples

The daily use of personal care products exposes us to various chemicals, including parabens. Parabens are commonly used as preservatives in cosmetics due to their strong antimicrobial properties. Excessive exposure to parabens from multiple products can have negative side effects on human health. Additionally, it poses a significant environmental concern as high concentrations of parabens have been found in environmental samples, leading to pollution and toxicity in aquatic species through indirect exposure. Therefore, it is crucial to monitor the presence of parabens in cosmetics and water samples. In this study, an electrochemical sensor was developed using a hybrid nanocomposite composed of vinyl functionalized polyhedral oligomeric silsesquioxane (V-POSS) embedded multi-layer graphene (MLG). The combination of these materials resulted in excellent charge transferability and conductivity, making them suitable for the sensor. The nanocomposite was characterized using various techniques such as Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), water contact angle measurements, and scanning electron microscopy (SEM). The electrochemical characterization of the V-POSS: MLG nano-interfacing element demonstrated a detection limit (S/N:3) of 0.29 nM for methylparaben (MP), 0.11 nM for ethylparaben (EP) and 0.2 nM for propylparaben (PP). Finally, the sensor was successfully applied to the analysis of cosmetics and water samples, showing good recovery rates (95–110 %) with minimal interference.

POSS/EHTPB synergistically toughened epoxy resin for cryogenic application

The high brittleness of epoxy resin at cryogenic temperature restricts their wide application in cryogenic engineering. In this study, polyhedral oligomeric silsesquioxane (POSS) with -Si-O-Si- molecular chains were synthesized, and the mechanical properties of diglycidyl ether of bisphenol A (E51 epoxy resin) were significantly enhanced at room temperature (RT) by incorporating a 4% POSS and curing agent 4,4′-diamino-diphenylmethane (DDM) as the E51/POSS/DDM resin system. Subsequently, by adding different contents of epoxidation hydroxyl-terminated polybutadiene (EHTPB) into the E51/POSS/DDM resin system, the EHTPB-E51/POSS/DDM resin system was prepared. The investigation into the impact of EHTPB content on the mechanical properties of EHTPB-E51/POSS/DDM resin system at room temperature (RT) revealed that EHTPB-E51/POSS/DDM resin system with 10% EHTPB exhibited the most favorable results. Specifically, the elongation at break, flexural strength, and critical stress intensity factor (KIC) were measured to be 6.82%, 143.75 MPa, and 1.83 MPa·m1/2, respectively. These values demonstrated a notable improvement of 53.3%, 26.9%, and 86.7% compared to those for the E51/DDM resin system. Concurrently, at 77 K, the elongation at break and critical stress intensity factor (KIC) increased by 37.8% and 73.5%, respectively. The toughening mechanism of the prepared EHTPB-E51/POSS/DDM resin system was further explored through resin-curing cross-linking simulation networks and SEM images of the fracture surface of resin samples. The study of EHTPB and POSS synergistically toughened epoxy resin provided a new efficient method to prepare epoxy resins with high toughness at low temperatures.

Ab initio molecular dynamics study of interactions between isolated polyhedral oligomeric silsesquioxane trisilanols and aluminum

Trisilanol polyhedral oligomeric silsesquioxane (POSS) are a category of inorganic–organic material that comprise an inorganic open cage silica structure, organic attachments, and silanol (SiOH) groups. Recently, trisilanol POSS was added to Al-based alloys, and found to promote substantial microstructural refinement, and improved mechanical strength and fatigue life compared to conventional compositions. Such microstructural modifications and property enhancements are usually attributed to silanolAl bonds that formed within the liquid-state, prior to solidification. However, details of such high-temperature chemical interactions remain unclear. Here, we performed ab initio molecular dynamics simulations at 1500 K, to probe the chemical interactions between isolated trisilanol POSS molecule and discreet Al atoms. Al atoms modified the silanol groups to form, two energetically favorable coordinate complexes: monodentate SiOAl and bidentate (SiO)2Al. Such complexes were formed by Al atoms attracting electrons towards themselves from the POSS molecule. Crucially, this bonding mechanism allowed trisilanol POSS to organize the neighboring Al atoms into geometric motifs that can potentially serve as nucleation sites within liquid-Al, and facilitate microstructural refinement.

Synthesis and evaluation of modified polyhedral oligomeric silsesquioxane (POSS) derivatives with luminescent Side-chains having charge-transfer characters

Abstract We describe here a synthesis and evaluation of polyhedral oligomeric silsesquioxane (POSS) derivatives having luminescent charge-transfer molecules. The electron withdrawing groups (EWG), such as trifluoromethyl groups, and electron donating groups (EDG), such as methoxy and dimethylamine groups, were introduced into π-conjugated systems connected at each vertex of the silica cube, and their optical properties were evaluated in solution and solid states. It was shown that the POSS scaffold hardly influenced the electronic structures of each substituent, meanwhile there were significant differences in electronic interactions between EWGs and EDGs depending on the order of connections from the silica cube. Finally, we obtained heat resistant luminescent materials having intermolecular charge-transfer characteristics.

Insight into the drying-mediated and thioether bond activated chiral inversion assembly of nano building blocks

Supramolecular materials are typically obtained from a solvent environment, while the assembled nano-structures always affected and unpredictably changed by irreversible evaporation of solvents, which brings great challenges for the precise controlling of assembled structures. Herein, a drying-mediated and thioether bond activated chiral inversion assembly behavior of organic/inorganic nano-building blocks polyhedral oligomeric silsesquioxane (POSS) was investigated. The POSS was modified by eight methylated terminal cysteine, while the existence of thioether bond could capture the hydrogen bonds belonging to amide groups during drying process, resulting in weaken of the inter-molecular hydrogen bonds and displacing the stacking of the nano-building blocks, which activates the forming of super-helical structures opposite to the original chirality. This research reveals the solvent-induced chiral assembly principle of the giant molecules and helpful for the construction of the precise architecture.

Development of fluorescence sensors for quantifying anions based on polyhedral oligomeric silsesquioxane that contains flexible side chains with urea structures

Development of fluorescence sensors for quantifying anions based on polyhedral oligomeric silsesquioxane that contains flexible side chains with urea structures

Progress in Polyhedral Oligomeric Silsesquioxane (POSS) Photoresists: A Comprehensive Review across Lithographic Systems.

This paper offers a comprehensive overview of the polyhedral oligomeric silsesquioxane (POSS) and POSS-based composites within the realm of photoresist resin. The study involves a systematic exploration and discussion of the contributions made by POSS across various lithographic systems, with specific emphasis on critical parameters such as film formation, sensitivity, resolution, solubility, and edge roughness. These lithographic systems encompass X-ray lithography (XRL), deep ultraviolet nanoimprint lithography (DUV-NIL), extreme ultraviolet lithography (EUV), and guided self-assembled lithography (DSA). The principal objective of this paper is to furnish valuable insights into the development and utilization of POSS-based photoresist materials in diverse lithographic contexts.

Optimization of the Thermally Conductive Low-k Polymer Dielectrics Based on Multisource Free-Volume Effects.

Polymers/polymer matrix composites possessing low dielectric constants (low-k polymer dielectrics) contribute to the advance of electronics, for instance, microprocessor chips, mobile phone antennas, and data communication terminals. However, the intrinsic long-chain structural characteristic results in poor thermal conductivities, which draw heat accumulation and undermine the outstanding low-k performance of polymers. Herein, multisource free-volume effects that combine two novel kinds of extra free volume with the known in-cage free volume of polyhedral oligomeric silsesquioxanes (POSSs) are discussed to reduce the capacity for dielectric constant reduction. The multisource free-volume effects of POSSs are associated with the thermal conductive network formed by the hexagonal boron nitride (BN) in the polymer matrix. The results show a decent balance between low-k performance (dielectric constant is 2.08 at 1 MHz and 1.98 at 10 GHz) and thermal conductivity (0.555 W m-1 K-1, 4.91 times the matrix). The results provide a new idea to maximize the free-volume effects of POSSs to optimize dielectric properties together with other desired performances for the dielectrics.