Polyhedral Oligomeric Silsesquioxane Compounds Research Articles

Synthesis and Characterization of Schiff Bases and Cu(II) and Ni(II) Complexes of Polyhedral Oligomeric Silsesquioxane (POSS) Compounds

Bu çalışmada, 3-aminopropiltrietoksisilan (APTES) ve N-(2-aminoetil)-3-aminopropiltrimetoksisilan (AEPTMS) kullanılarak iki farklı polihedral oligomerik silseskioksan (POSS) sentezlenmiştir. Elde edilen bu POSS bileşikleri, salisilaldehit ve 5-bromosalisilaldehit ile kondenzasyon tepkimesi sonucu POSS Schiff bazları sentezlenmiştir. POSS ve ligand özelliğindeki türevlerinin yapıları spektroskopik (Elementel analiz (C, H, N), 1H-NMR, 29Si NMR, FT-IR) yöntemlerle aydınlatılmıştır. Schiff Bazlarının Cu(II) ve Ni(II) metal kompleksleri sentezlenmiştir. İzole edilen POSS Schiff bazı metal komplekslerinin yapıları FT-IR, Magnetik duyarlılık terazisi ve ICP-OES ile aydınlatılmaya çalışılmıştır. Sonuçlar, metal iyonlarının Schiff bazlarına fenolik oksijen ve azometin azotu üzerinden bağlandığını göstermiştir.

Engineering two nitrogen-containing polyhedral oligomeric silsesquioxanes (N-POSSs) to enhance the fire safety of epoxy resin endowed with superior thermal stability

Despite remarkable advances in developing flame retardants and smoke suppressants for epoxy resin (EP), engineering nitrogen-containing polyhedral oligomeric silsesquioxane (N-POSS) to impart superior fire safety properties to EP has remained an intractable challenge. In this work, two nitrogen-containing polyhedral oligomeric silsesquioxanes (N-POSSs), namely, aminoethyl-aminopropyl-hepta-phenyl polyhedral oligomeric silsesquioxane (AEAP-POSS) and aminopropyl-hepta-phenyl polyhedral oligomeric silsesquioxane (AP-POSS), were synthesized through the “corner-capping” reaction. The molecular structures of N-POSSs were fully characterized by FTIR, 1H NMR, 29Si NMR and MALDI-TOF MS, and the synthesized AEAP-POSS and AP-POSS were introduced into EP to solve the shortcomings of flammability. TGA results showed that the incorporation of 4 wt% N-POSS nanoparticles distinctly improved the char residue at 800 °C, which significantly enhanced the thermal stability of the EP composites. When 4 wt% of AP-POSS was introduced into EP, reductions in the peak of heat release rate (p-HRR), fire growth index (FGI), peak of smoke production rate (p-SPR), and the peak of CO production rate (p-COP) reached to 60.6%, 70.2%, 52.3% and 60.4%, respectively. Subsequently, TG-FTIR and XPS were utilized to investigate the flame retardancy and smoke suppression mechanism. Our work presented a considerable advancement for the facile fabrication of flame retardants based on nitrogen-containing polyhedral oligomeric silsesquioxane compounds.

Unsymmetric Dumbbell-Shaped Polyhedral Oligomeric Silsesquioxane (POSS) Compound as a Single-Component POSS Hybrid.

Dumbbell-shaped polyhedral oligomeric silsesquioxane (POSS) derivatives, in which two POSS units are linked through a bridge, have attracted attention in the last decade. Here, we prepared an unsymmetric dumbbell-shaped POSS derivative (3Ph-iBu) in which isobutyl- and phenyl-substituted POSS units are linked by a disiloxane unit and compared its thermal properties with those of the corresponding symmetric isobutyl- and phenyl-substituted dumbbell-shaped POSS derivatives (3iBu-iBu and 3Ph-Ph, respectively). The symmetric isobutyl- and phenyl-substituted dumbbell-shaped POSS derivatives, 3iBu-iBu and 3Ph-Ph, were almost completely phase-separated during a mixing process. This phase separation is due to the limited solubility of phenyl-substituted POSS compounds, which are only soluble in tetrahydrofuran (THF) and insoluble in hydrocarbons such as n-hexane and toluene, while the isobutyl-substituted POSS derivatives exhibit a wider spectrum of soluble solvents. The unsymmetric dumbbell-shaped POSS, 3Ph-iBu, showed hybrid properties of solubility in solvents and thermal behaviors. Differential scanning calorimetric (DSC) analysis showed that enthalpy of the phase transition of 3Ph-iBu was significantly lower than those of the mixture of 3iBu-iBu and 3Ph-Ph. No apparent melting behavior was observed above the phase transition. The thermal degradation of the weakest isobutyl substituents improves in the present single-component hybrid structure.

Effect of polyhedral oligomeric silsesquioxane on combustion performance of HTPB propellants

HTPB-based (hydroxyl‑terminated polybutadiene) propellants containing aluminum and ammonium perchlorate (AP) were prepared with 1 wt% polyhedral oligomeric silsesquioxanes (POSS) and Fe2O3, respectively. The influences of POSS compounds on combustion performance of HTPB propellants were investigated. Four POSS compounds, octa (phenyl) silsesquioxane (OPS), octa (nitrophenyl) silsesquioxane (ONPS), octa (dinitrophenyl) silsesquioxane (ODNPS) and octa (aminophenyl) silsesquioxane (OAPS) were used. Their compatibility with the HTPB propellant components were tested by DSC analysis. Their combustion heats of and sensitivities were measured by oxygen bomb calorimeter and friction and impact tests, respectively. The results show that ODNPS and ONPS belong to low sensitive energetic compounds. The POSS compounds have good compatibility with the components of HTPB propellant. The burning rates of the HTPB propellants were measured in combustion chamber with transparent window under pressure. The combustion behaviors of the propellants under atmospheric pressure were recorded using high-speed camera. The condensed-phase combustion products were collected and studied through the SEM observation, XRD analysis and particle size measurements. The POSSs can increase the burning rates of HTPB propellants. With the ODNPS, the burning rate of HTPB propellant is similar to that of Fe2O3. The addition of the OPS, OAPS and Fe2O3 reduces the combustion heats of propellants, while with ONPS and ODNPS, the combustion heats are close to that of the HTPB propellant. POSS compounds can promote the combustion of aluminum in the propellants, inhibit the agglomeration of aluminum particles in the combustion process, and reduce the size of condensed phase products. These should correlate to the formation of the nano carbon layers from the POSS compounds in combustion of the propellants.

Synthesis of Functionalized Silsesquioxane Nanomaterials by Rhodium‐Catalyzed Carbene Insertion into Si−H Bonds

AbstractWe report carbene insertion into Si−H bonds of polyhedral oligomeric silsesquioxanes (POSS) for the synthesis of highly functionalized siloxane nanomaterials. Dirhodium(II) carboxylates catalyze insertion of aryl‐diazoacetates as carbene precursors to afford POSS structures containing both ester and aryl groups as orthogonal functional handles for further derivatization of POSS materials. Four diverse and structurally varied silsesquioxane core scaffolds with one, three, or eight Si−H bonds were evaluated with diazo reactants to produce a total of 20 new POSS compounds. Novel diazo compounds containing a fluorinated octyl group and boron‐dipyrromethene (BODIPY) chromophore demonstrate the use of highly functionalized substrates. Transformations of aryl(ester)‐functionalized POSS compounds derived from this method are demonstrated, including ester hydrolysis and Suzuki–Miyaura cross‐coupling.

Synthesis of Functionalized Silsesquioxane Nanomaterials by Rhodium-Catalyzed Carbene Insertion into Si-H Bonds.

We report carbene insertion into Si-H bonds of polyhedral oligomeric silsesquioxanes (POSS) for the synthesis of highly functionalized siloxane nanomaterials. Dirhodium(II) carboxylates catalyze insertion of aryl-diazoacetates as carbene precursors to afford POSS structures containing both ester and aryl groups as orthogonal functional handles for further derivatization of POSS materials. Four diverse and structurally varied silsesquioxane core scaffolds with one, three, or eight Si-H bonds were evaluated with diazo reactants to produce a total of 20 new POSS compounds. Novel diazo compounds containing a fluorinated octyl group and boron-dipyrromethene (BODIPY) chromophore demonstrate the use of highly functionalized substrates. Transformations of aryl(ester)-functionalized POSS compounds derived from this method are demonstrated, including ester hydrolysis and Suzuki-Miyaura cross-coupling.

Polytriazole resins toughened by an azide-terminated polyhedral oligomeric silsesquioxane (OADTP)

Abstract An azido-terminated polyhedral oligomeric silsesquioxane (POSS) compound, octakis(azidopropyl-3-oxycarbonyl-1-decyl-10-thiopropyl-3-)POSS (OADTP), is synthesized and characterized. POSS-polytriazole (PTA) resins are prepared from an azide, an alkyne monomer, and OADTP. The toughening effect of OADTP on PTA resins is analyzed by impact performance test and electronic microscope characterization, and the thermal performance of resins is measured by thermogravimetric analysis and dynamic mechanical analysis. The results show that the addition of the POSS can improve the mechanical properties of PTA resins. The impact strength of POSS-PTA resins first increases and then decreases with the increase in the POSS compound, and the maximum one arrives at 54.8 kJ m−2 which increases by 44.2% as compared to 38 kJ m−2 of the PTA resin. A good thermal stability remains in POSS-PTA resins.

Analysis of the Stereoisomers (cis, trans) of Polyhedral Oligomeric Silsesquioxane Compounds by UHPSFC-QTof MS

Polyhedral oligomeric silsesquioxanes (POSSs) are a class of important hybrid inorganic/organic materials. When POSSs are used as the building block in polymerization, the materials show superior performance over their organic counterparts in many areas due to the special Si–O cage structure. However, the stereoisomers (cis, trans) of polyhedral oligomeric silsesquioxane (POSS) show some differences in improving polymer property and it is difficult to get the pure stereoisomer by synthesis. Therefore, a method is required to separate and purify the mixture of POSSs. In this study, the isomers of POSS compounds and the impurities were separated by ultra-high performance supercritical fluid chromatography coupled quadrupole time-of-flight mass spectrometry (UHPSFC-QTof MS). To separate the isomers of POSS, the crucial parameters of UHPSFC-QTof MS were investigated. Under the optimal conditions, the isomers of product and impurities were separated in 4 min. On account of exact mass measurement, some impurities were identified. This is the first study on the analysis of isomers of POSS using UHPSFC-QTof MS. Based on this analysis method, it is helpful to optimize the conditions of synthesis.

Comparing the Electrorheological Effect of Polyhedral Silsesquioxane Cage Structures with Different Numbers of Cyanopropyl Functional Groups.

Previous research has shown that polyhedral oligomeric silsesquioxane (POSS) particles in silicone oil show electrorheological (ER) activity. The effect of the number of same functional groups attached to POSS cage structures on the ER activity of these structures is discussed in this article. Two compounds of the octahedral geometry (T8) of cyanopropyl POSS (cPOSS) were used for this investigation. One of the compounds (monofunctionalized cPOSS) was commercially available, and the other (octafunctionalized cPOSS) was synthesized. The effects of the number of cyanopropyl functional groups attached to the inorganic silicon–oxygen core structure of the POSS compounds on the rheological properties are demonstrated through steady flow and oscillatory tests. Particular attention is paid to how the number of cyano functional groups affects the behavior of these suspensions of cPOSS compounds in silicone oil under increasing electric field strength. The research also contributed answers to the effects of changing the concentration of the cPOSS particles in the suspension. The flow curve was described by the Herschel–Bulkley model, and the yield stress values were ascertained from the model. The dielectric characterization was also done to support the ER response results, which showed that the octafunctionalized compound gave a better response. The differences in the ER properties of these compounds have also been discussed with the tests.

Electrorheological Effects of Synthesized Octa-cyanopropylsilsesquioxane Cage Structure.

This article introduces a new electrorheological (ER) fluid. A molecular cage structure for electrorheological applications has been synthesized, and the ER behavior of the octa-functionalized polyhedral oligomeric silsesquioxane (POSS) variant in silicone oil (PDMS) has been shown. The hydrolyzation route has been used in the synthesis, the microstructure has been displayed using scanning electron microscopy, the yield has been ascertained, and the compound has been characterized. The rheological properties are demonstrated on the ER fluid through steady flow and oscillatory tests to investigate the effects of change in concentration on the functional group attached to the inorganic silicon–oxygen core structure of the POSS compound. The electrorheological efficiency was analyzed, and dielectric characterization was done. The flow curve was described by the Herschel–Bulkley model, and yield stress values were derived from the model. The octa-cyanoPOSS/PDMS electrorheological fluid has been shown to have ER activity.

POSS Compounds as Modifiers for Rigid Polyurethane Foams (Composites).

Three types of polyhedral oligomeric silsesquioxanes (POSSs) with different functional active groups were used to modify rigid polyurethane foams (RPUFs). Aminopropylisobutyl-POSS (AP-POSS), trisilanoisobutyl-POSS (TS-POSS) and octa(3-hydroxy-3-methylbutyldimethylsiloxy-POSS (OH-POSS) were added in an amount of 0.5 wt.% of the polyol weight. The characteristics of fillers including the size of particles, evaluation of the dispersion of particles and their effect on the viscosity of the polyol premixes were performed. Next, the obtained foams were evaluated by their processing parameters, morphology (Scanning Electron Microscopy analysis, SEM), mechanical properties (compressive test, three-point bending test, impact strength), viscoelastic behavior (Dynamic Mechanical Analysis, DMA), thermal properties (Thermogravimetric Analysis, TGA, thermal conductivity) and application properties (contact angle, water absorption). The results showed that the morphology of modified foams is significantly affected by the fillers typology, which resulted in inhomogeneous, irregular, large cell shapes and further affected the physical and mechanical properties of the resulting materials. RPUFs modified with AP-POSS represent better mechanical properties compared to the RPUFs modified with other POSS.

Organosiloxane and Polyhedral Oligomeric Silsesquioxanes Compounds as Chemiluminescent Molecular Probes for Direct Monitoring Hydroxyl Radicals.

Despite the tremendous progress in the research of luminescent probes for reactive oxygen species (ROS), designing luminescent ROS probes with high sensitivity for the individual ROS is still retarded because of their high reactivity and the rapid and complex interconversion reactions among them. Herein, organosiloxane and polyhedral oligomeric silsesquioxanes (POSS) compounds are designed as a novel class of luminescent molecular probes to produce extraordinary chemiluminescence (CL) based on the specific electrophilic attack of •OH. No CL signal can be obtained by the other ROS and strong oxidants. AEAP-POSS formed by hydrolytical condensation of 3-(2-aminoethylamino)propyl]trimethoxysilane (AEAPTMS) is constructed to covalently link a dye molecular, perylene diimide derivative (PDI), and an intramolecular chemiluminescence resonance energy transfer (CRET) system is obtained to realize the red shift of CL wavelength and enhanced CL intensity. This probe based on CRET is applied to monitor inherent •OH in ambient particular matter (PM2.5 and PM10). Density functional theory (DFT), ion chromatograph, X-ray photoelectron spectroscopy (XPS), particle size analysis, and fluorescence spectrum (FL) are applied to study the CL mechanism. These studies discover that electronically carbonyl CH3CO• is the CL emitter, and the silicon-oxygen skeleton in the organosiloxane and POSS compounds plays the key role in undergoing chemiluminescence (CL) reaction.

The wetting properties of Langmuir-Blodgett and Langmuir-Schaefer films formed by DPPC and POSS compounds.

The possibility of modification of surface wettability is especially desirable in implantology. This effect is achieved by coating a given material with thin films containing nanoparticles of different chemical properties. In recent years, much interest has been paid to supported phospholipid bilayers (SPBs), because they can be exploited in novel biotechnological devices such as biosensors and mimetic membrane-coated implants. In view of the above, we decided to study the modification of wetting properties of phospholipid layer by two types of polyhedral oligomeric silsesquioxanes (POSS) with different functional groups attached to the silica open-cage. The POSS and phospholipid (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) were vertically (Langmuir-Blodgett; LB) and horizontally (Langmuir-Schaefer; LS) deposited on quartz substrates to form a thin layer structure. The advancing contact angles on the modified surface coated with thin films were measured. The surface free energy (SFE) of DPPC, POSS and their mixed DPPC/POSS films was estimated by using Owens-Wendt-Rabel-Käelbe (OWRK) method. It was shown that the chemical structure of POSS used as a modifier influence the wetting properties of modified quartz surface. Incorporation fluoroalkyl-POSS into DPPC monolayer leads to obtaining a more hydrophobic film, while the addition of polyethylene glycol-POSS creates a more hydrophilic film. The transfer of the film with a more condensed structure led to a more hydrophobic material. The deposition technique (horizontal or vertical) had a particular impact on the modification of wettability of quartz surface coated with monocomponent fluoroalkyl-POSS film, whereas for the modification with mixed DPPC/POSS systems the choice of transfer method was not so significant.

Synthesis of new polyhedral oligomeric silsesquioxane derivatives as some possible antimicrobial agents

1,3-Dipolar cycloaddition reactions were studied to synthesize Polyhedral oligomeric silsesquioxane (POSS)-based norbornyl imide derivatives containing izoxazoline groups in good yields. And also 1,3-dipolar cycloaddition reactions of azomethine ylides with POSS-based norbornene dipolarophiles for a synthesis of the novel POSS-based norbornane-fused spiro-1,3-indandionolylpyrrolidines are reported. All newly synthesized POSS compounds were structurally characterized by FTIR, 1H, 13C NMR, HRMS and GC/MS analyses.

A critical assessment of multifunctional polymers with regard to their potential use in structural applications

Multi Wall Carbon Nanotubes (MWCNTs) and Polyhedral Oligomeric Silsesquioxanes (POSS) are common additives to simultaneously enhance electrical conductivity and flame resistance. In the present work, the synergistic effect of the addition of MWCNTs and two different POSS compounds, DodecaPhenyl POSS (DPHPOSS) and Glycidyl POSS (GPOSS), on the mechanical behavior of multifunctional polymers subjected both to quasi-static as well as to fatigue loading was investigated. The results of the mechanical tests were discussed supported by Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) analyses. The results showed that the incorporation of MWCNTs in the resin containing GPOSS determines a slight decrease in the flexural modulus compared to the unfilled resin. The material filled with MWCNTs and DPHPOSS shows a higher reduction of the flexural modulus as compared to the other analyzed materials. The same trend was observed also for the flexural strength; more than 50% decrease of the flexural strength of the material filled with MWCNTs and DPHPOSS is detected. As far as the fatigue is concerned, it seems that the incorporation of the flame retardants led to an appreciable decrease in the fatigue life. The decrease in the mechanical properties of the nanofilled resin loaded with DPHPOSS is most likely due to the presence of aggregates of DPHPOSS crystals in the matrix. This hypothesis is confirmed by EDX analysis which shows that DPHPOSS forms some small aggregates, whereas GPOSS, being molecularly solubilized in the epoxy formulation, shows mechanical performance more similar to the sample loaded only with carbon nanotubes.

Effect of chemical structure of fluorinated polyhedral oligomeric silsesquioxanes on formation of Langmuir monolayers and Langmuir-Blodgett films

Fluorinated polyhedral oligomeric silsesquioxanes (F-POSS) due to their nanoscale hybrid structure coupled with hydrophobic substituted chains have drawn significant attention as highly hydrophobic and oleophobic materials. That is why the surface properties of such compounds at the molecular level should be analyzed in details. Therefore we studied four different fluorinated closed cage polyhedral oligomeric silsesquioxanes (POSS) using Langmuir and Langmuir-Blodgett (LB) techniques. The monolayer behavior was investigated by measurements of the surface pressure-area (π-A) isotherm and morphology of the films was visualized using Brewster angle microscopy (BAM). The rheological behavior was investigated using interfacial shear rheometer (ISR). The unusual properties of these silsesquioxanes result from their unsymmetrical structure. The hydrophobic character of their fluorinated substituents, combined with the hydrophilicity of the trimethoxysilane moieties lead to specific monolayer properties. The compounds were found to form stable monolayers at the air/water (A/W) interface however the surface activity of POSS derivatives decreases with increasing content of fluorinated moieties in the POSS structure. The monolayers of the studied POSS compounds were also successfully transferred onto the solid substrates as Y-type Langmuir-Blodgett films. The wettability and the structure of the LB film were investigated by measuring the static water contact angle on the glass surface. The presence of fluorinated moieties in the structure of POSS molecules governs the enhanced hydrophobic properties of solid substrate modified by the LB film.

POSS-containing hybrid nanomaterials based on thiol-epoxy click reaction

Organic-inorganic nanocomposites were designed by combining a commercial epoxy resin (diglycidyl ether of bisphenol A - DER) and a multi-thiol crosslinking agent with a “clickable” polyhedral oligomeric silsesquioxane (POSS) compound. 1-methylimidazole was employed as a catalyst to yield highly efficient thiol-Michael addition reaction materials. The equivalent ratio between epoxy: thiol was maintained 1:1 in all the formulations and therefore the homopolymerization reaction of epoxy resin is unlikely to occur. The synergistic effect of the thiol compound and mono-functionalized POSS bearing one epoxy/thiol reactive group on the curing process was investigated in detail. We assume that the mechanistic pathway of the thiol-epoxy click-reaction increases in complexity due to the introduction of reactive POSS in the system. The incorporation of mono-epoxy or mono-thiol POSS in the thiol–epoxy organic host leads to distinct thermo-mechanical behavior of the crosslinked networks due to the fact that the POSS compound will chemically interact in the click reaction.

Janus [3:5] Polystyrene–Polydimethylsiloxane Star Polymers with a Cubic Core

We describe the precision synthesis and self-assembly of a series of Janus star polymers with mixed [3:5] heteroarms of polystyrene (PS) and polydimethylsiloxane (PDMS) precisely arranged on a cubic scaffold of T8 polyhedral oligomeric silsesquioxane (POSS) in a spatially segregated fashion. The synthesis begins with a Janus POSS compound with three 2-hydroxylethyl groups on one face and five vinyl pendant groups on the rest vertexes. Facilitated by esterification and a “click” adaptor, two types of polymer arms are attached efficiently by sequential “click” reactions, which constitutes a general approach for modular synthesis of such Janus star polymers. The Janus feature is thoroughly characterized using NMR, FT-IR, SEC, and MALDI-TOF mass spectrometry, and the self-assembled structures are studied by small-angle X-ray scattering (SAXS) experiments. With increasing molecular weight of PS arm, the self-assembled phase transits from lamellae (LAM) to hexagonally packed cylinder (HEX) and further to invers...

Toughening of Epoxy Adhesives by Combined Interaction of Carbon Nanotubes and Silsesquioxanes.

The extensive use of adhesives in many structural applications in the transport industry and particularly in the aeronautic field is due to numerous advantages of bonded joints. However, still many researchers are working to enhance the mechanical properties and rheological performance of adhesives by using nanoadditives. In this study the effect of the addition of Multi-Wall Carbon Nanotubes (MWCNTs) with Polyhedral Oligomeric Silsesquioxane (POSS) compounds, either Glycidyl Oligomeric Silsesquioxanes (GPOSS) or DodecaPhenyl Oligomeric Silsesquioxanes (DPHPOSS) to Tetraglycidyl Methylene Dianiline (TGMDA) epoxy formulation, was investigated. The formulations contain neither a tougher matrix such as elastomers nor other additives typically used to provide a closer match in the coefficient of thermal expansion in order to discriminate only the effect of the addition of the above-mentioned components. Bonded aluminium single lap joints were made using both untreated and Chromic Acid Anodisation (CAA)-treated aluminium alloy T2024 adherends. The effects of the different chemical functionalities of POSS compounds, as well as the synergistic effect between the MWCNT and POSS combination on adhesion strength, were evaluated by viscosity measurement, tensile tests, Dynamic Mechanical Analysis (DMA), single lap joint shear strength tests, and morphological investigation. The best performance in the Lap Shear Strength (LSS) of the manufactured joints has been found for treated adherends bonded with epoxy adhesive containing MWCNTs and GPOSS. Carbon nanotubes have been found to play a very effective bridging function across the fracture surface of the bonded joints.

Reactive Hybrid of Polyhedral Oligomeric Silsesquioxane (POSS) and Sulfur as a Building Block for Self-Healing Materials.

This work demonstrates a new reactive and functional hybrid (S-MMA-POSS) of polyhedral oligomeric silsesquioxane (POSS) and sulfur prepared with a direct reaction between a multifunctional methacrylated POSS compound (MMA-POSS) and elemental sulfur (S8 ) through the "inverse vulcanization" process. S-MMA-POSS is an effective building block for imparting self-healing ability to the corresponding thermally crosslinked POSS-containing nanocomposites through a self-curing reaction and co-curing reaction with conventional thermosetting resins. Moreover, S-MMA-POSS is also a useful precursor for preparation of materials with high transparency in mid-infrared region.