Types Of POSS Research Articles

Organic–Inorganic Polyimides with POSS Cages in the Main Chains: An Impact of POSS R Groups on Morphologies and Properties

Two well-defined POSS diamines were synthesized with phenyl (Ph) and iso-butyl (i-Bu) POSS trisilanols as the starting compounds. This approach involves the protection and deprotection of silanol hydroxyl groups with phenylboronic acid and pinacol, followed by the silylation of silanol hydroxyl groups with mono- and dichlorosilanes. With this route of synthesis, two well-defined divinyl POSS macromers were obtained, as evidenced by 1H, 29Si NMR, and mass spectroscopy. These two divinyl POSS macromers were further functionalized into well-defined POSS diamines via the Heck reaction with p-bromoaniline. The successful synthesis of POSS diamines enabled the synthesis of organic–inorganic polyimides with the POSS cages in the main chains. More importantly, the syntheses of these two POSS diamines allowed the examination of the effect of POSS R groups (i.e., Ph and i-Bu) on the morphologies and thermomechanical and dielectric properties of organic–inorganic polyimides. Notably, the types of POSS R groups exerted a profound impact on the morphologies and properties of the organic–inorganic polyimides.

Improved interfacial adhesion with the help of functional polyhedral oligomeric silsesquioxanes in silicone rubber/rayon fiber composites: Physical, mechanical, thermal, and morphological properties

AbstractThe aim of this article is to improve the interfacial adhesion between silicone rubber (SR) and Rayon fiber by the help of functional hybrid POSS nanoparticles. Two POSS types were compared, octavinyl‐POSS (O‐POSS) and methacryl‐POSS (M‐POSS), having reactive CC double bonds that can impart in peroxide crosslinking. O‐POSS is nonpolar, whereas M‐POSS is polar and is able to make H‐bond with Rayon fibers. POSS type and their concentrations were examined as the experimental parameters. H‐adhesion tests indicated that both POSS types enhanced the adhesion of SR composites to Rayon fibers compared with control recipe. Specifically, slightly higher values were obtained with the use of M‐POSS. It was observed that both O‐POSS and M‐POSS slowed down the curing rate but increased the degree of crosslinking. The cure extent of O‐POSS containing composites was found to be higher than that of M‐POSS containing ones. Thermal gravimetric analyses revealed that thermal stability of SR composites was significantly improved by the addition of POSS particles. Higher char yield and degradation temperatures were obtained with O‐POSS at higher loadings with respect to M‐POSS. The POSS distribution at lower loading levels was found to be homogenous for both POSS types as observed from scanning electron microscope and transmission electron microscope.

The Potential Use of Epoxy‐POSS as a Reactive Hybrid Compatibilizers for PLA/PBAT Blends: “Effect of PBAT Molecular Weight and POSS Type”

This article focuses on the effect of molecular weight of poly(butylene adipate‐co‐terephthalate) (PBAT) on the immiscible poly(lactic acid) (PLA)/PBAT blends compatibilized with epoxidized polyhedral oligomeric silsesquioxanes (Epoxy‐POSSs) having different numbers of epoxy groups per molecule. Mechanical, thermomechanical, thermal, rheological, and morphological properties of the blends were investigated as a function of PBAT molecular weight and epoxy‐POSS type. Mechanical tests revealed that all epoxy‐POSS types significantly improved the performance of the blends containing low‐molecular‐weight PBAT. On the other hand, epoxy‐POSS with three epoxy functional groups (TriEpPOSS) and Epoxy‐POSS with multiple‐epoxy functional groups (MuEpPOSS) only slightly improved the performance of blends with high‐molecular‐weight PBAT. Thermomechanical and thermal test results supported that the compatibilization effects of the epoxy‐POSSs were more prominent in the PLA/PBAT blends with low‐molecular‐weight PBAT due to the observation of the shifts in the glass transition temperatures of the PLA phase. According to the rheological results, the addition of epoxy‐POSSs increased the interactions between the PLA and PBAT phases much more effectively in the PLA/PBAT with low‐molecular‐weight PBAT. The dispersed phase size of the PBAT further decreased in the low‐molecular‐weight PLA/PBAT blend system due to the enhanced compatibility much better. POLYM. ENG. SCI., 60: 398–413, 2019. © 2019 Society of Plastics Engineers

Effects of POSS vertex group on structure, thermal and mechanical properties of PMMA/POSS hybrid materials

This paper explores the preparation of polymethyl methacrylate (PMMA/POSS) hybrid materials in bulk polymerization. The effects of pendant polyhedral oligomeric silsesquioxane type and content were investigated. The materials were characterized by Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), field emission scanning electron microscopy (SEM-FEG), wide-angle X-ray diffraction (WAXD), synchrotron small-angle X-ray scattering (SAXS), thermal, thermo-mechanical, and mechanical properties. All materials showed no particles agglomerated on a micrometric scale, which contributed to the formation of optically transparent materials. Regardless of the POSS type or content, the use of POSS produced no change in the molecular packing of PMMA. A higher relation between the chain size/topological restrictions of movement was not observed for significant changes in the glass transition temperature, softening temperature, or thermal deflection. The interfacial thickness (E) was dependent on the amount and type of POSS used. Lower E values caused a greater increase in elastic modulus.

The influence of POSS type on the properties of PLA

In this study, the effects of reactive and non‐reactive poly(hedral oligomeric silsesquoxane) (POSS) type and their loading level on the mechanical, morphological and thermal properties of PLA composites were investigated for the first time in the literature. A decrease in the melt viscosity of PLA was obtained from the vertical force measurements in the presence of POSS particles except for high O‐POSS loading level. This played an important role for power consumption during micro‐compounding process. The mechanical test results showed that, the elastic‐modulus and yield strength of the PLA/POSS composites were lower than pure PLA in most cases. Moreover, a significant improvement in Izod impact strength of PLA composites was achieved by incorporation of POSS particles into PLA regardless of POSS type. Morphological analysis showed that POSS particles dispersed homogeneously in polymer matrix for all compositions. The glass transition temperature of PLA decreased with the addition of POSS particles. POSS particles also enhanced the decomposition temperature of PLA. POLYM. COMPOS., 37:1497–1506, 2016. © 2014 Society of Plastics Engineers

Effect of functionality of polyhedral oligomeric silsesquioxane [POSS] on the properties of sulfonated poly(ether ether ketone) [SPEEK] based hybrid nanocomposite proton exchange membranes for fuel cell applications

Organic–inorganic hybrid nanocomposite membranes were prepared using three different types of POSS i.e., PEG POSS® cage mixture (PPOSS), trisilanol phenyl POSS® (TSP POSS) and trisulfonic acid isobutyl POSS® (SPOSS) at a fixed loading of 2% (w/w) as filler and SPEEK with degree of sulfonation (DS) 55% as polymer matrix. The influence of POSS functionality on hybrid membrane's thermo-mechanical properties, morphology, water uptake and proton conductivity was investigated. Thermal and mechanical stability of hybrid membranes increased upon incorporation of POSS. The size and distribution of POSS particles into SPEEK matrix was studied using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) and it was found that TSP POSS and PPOSS based membranes showed smaller particle size and uniform distribution as compared to SPOSS based membranes which consequently affect the water uptake and proton conductivity of these hybrid membranes. The water uptake studies were carried out at three different temperatures i.e. 30, 80, 100 °C for 24 h and POSS based composite membranes showed higher water uptake and proton conductivity compared to neat SPEEK membranes. The highest proton conductivity (64.6 mS/cm) was observed for TSP POSS containing membrane which is more than double of neat SPEEK (31.3 mS/cm) membrane. The composite membrane containing TSP POSS can be considered as suitable membrane for PEMFCs applications.

POSS-based luminescent hybrid material for enhanced photo-emitting properties

In this present work, we have developed a novel POSS type monomer ligand “2,6-pyridinediamine-bis-(propanylheptaisobutyl POSS)” (PDC-POSS) and utilized in the preparation of potential luminescent hybrid complex Eu-PDC-POSS with an inner transition metal ion Eu3+. The solubility and photo-emitting properties of new Eu-PDC-POSS hybrid material were studied. The precursor PDC-POSS was synthesized by treating (3-aminopropyl)heptaisobutyl POSS with PDC (2,6-pyridinedicarboxylic acid chloride), and then coordinated with Eu3+ using europium nitrate to afford Eu-PDC-POSS hybrid material. The europium-doped hybrid material was characterized using fourier transform infrared spectroscopy, and scanning electron microscopy along with energy dispersive X-ray analysis. The photo emitting properties were studied using a fluorescence spectrophotometer in which, the results showed enhancement in red emission peak at 618 nm for Eu-PDC-POSS, when compared to that of a known solgel-based material Eu-PDC-solgel.

POSS reinforced PET based composite fibers: “Effect of POSS type and loading level”

In this study, the effects of poly(hedral oligomeric silsesquoxane) (POSS) type and loading level on the mechanical, morphological and thermal properties of melt-spun PET-based composite fibers were investigated. Three different epoxy, hydroxyl or amine functional POSS types were compared. The thermal, morphological and mechanical properties were investigated. It was found that all the three POSS types generally demonstrated nucleating agent behavior, suggested by lower cold crystallization temperatures along with higher melt crystallization temperatures. Among the three types of POSS particles, addition of 1wt% hydroxyl functional POSS resulted in five times increased tensile modulus in comparison to the neat PET fiber. This can be explained by the combined effect of reinforcement with higher level of crystalline content in addition to the presence of more oriented amorphous domains. On the other hand, epoxy terminated POSS/PET composite fibers exhibited doubled tensile modulus with respect to the neat PET fiber; however, the results obtained on amine terminated APOSS-PET fiber did not have any significant trend.

Effects of poss nanoparticles on ABS‐g‐Ma thermo oxidation resistance

AbstractThermo oxidative degradation at and beyond processing temperatures has been carried out on ABS copolymer grafted with Maleic Anhydride (ABS‐g‐Ma) and three nanocomposites with the above material melt‐blended with different types of POSS, being amino‐propyl isobutyl (APOSS), glycidyl (GPOSS), and trisilanol (TPOSS). The incorporation adequacy of the nanofillers into the matrix has been assessed with scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), whereas the quantification of the thermal degradation behavior of each sample was carried out through infrared spectrography (FTIR), thermogravimetric analysis (TGA) including the degradation kinetics and color spectrophotometry (Cielab). Although the results show adequate incorporation and miscibility of the nanofillers into the matrix, the GPOSS and the TPOSS nanocomposites provided no relevant improvements in thermal stability when compared with the base ABS‐g‐Ma, and the APOSS blend exhibits a very slight decay in almost all the quantitative analysis carried out in this work. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Enhancement of POM thermooxidation resistance through POSS nanoparticles

Thermooxidative degradation at and beyond processing temperatures has been carried out on polyoxymethylene (POM) enhanced with four different types of POSS, being Glycidyl, GlycidylIsobutyl, Aminopropylisobutyl, and Poly(ethylene glycol). The quantification of such degradation was carried out through FTIR spectrography, color spectrophotometry, and thermogravimetric analysis methods. The results showed that the presence of POSS in the blend improves dramatically the thermal stability of the POM matrix. The best performance was found with Aminopropylisobutyl, whereby the onset of degradation temperature increased by more than 50°C. Said improvement is referred to the conditions where the nanocomposite developed only 2% of carbonyl yield and 8% of yellowing of the 100% deterioration suffered by the standard POM copolymer. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Pebax/POSS mixed matrix membranes for ethanol recovery from aqueous solutions via pervaporation

Novel mixed matrix membranes made of polyether-block-amide/polyhedral oligosilsesquioxane (Pebax/POSS) have been developed and investigated in this study for ethanol recovery via pervaporation separation. Two types of POSS; namely, octa(3-hydroxy-3-methylbutyldimethylsiloxy) (AL0136) and disilanolisobutyl (SO1440), were incorporated into Pebax membranes. The effects of POSS loading, feed ethanol concentration and feed temperature on pervaporation performance of the newly developed mixed matrix membranes (MMMs) have been studied. The incorporation of POSS nanoparticles improve the pervaporation performance of the hybrid membranes significantly. At 2 wt.% POSS loading, both permeation flux and separation factor of ethanol/water reach maximum values, which are 183.5 g/m 2 h and 4.6 for Pebax/AL0136 and 125.8 g/m 2 h and 4.1 for Pebax/SO1440, respectively. Pebax/AL0136 MMMs give better performance than Pebax/SO1440 MMMs, probably due to its higher affinity towards ethanol. Experimental results show that an increase in feed ethanol concentration results in an increase in flux, but decreases in separation factor and membrane selectivity. Flux increases but permeability decreases with an increase in operating temperature due to the increase in driving forces and the reduction in permeant sorption, respectively. Separation factor and selectivity are also observed to increase with increasing operating temperature. The changes in driving force, cluster formation, membrane swelling and interaction among permeating molecules play essential roles for the observed trends. This work may provide useful insights of mixed matrix membranes, especially those containing POSS for pervaporation recovery applications.

Morphology, rheological behavior, and thermal stability of PLA/PBSA/POSS composites

AbstractOctavinyl POSS (vPOSS) and epoxycyclohexyl POSS (ePOSS) were separately incorporated into the poly(lactic acid)/poly(butylene succinate‐co‐adipate) (PLA/PBSA) blend by melt mixing. Field emission scanning electron microscopy and X‐ray diffraction analysis revealed that vPOSS existed as crystalline aggregates, whereas ePOSS was more uniformly dispersed in the composites. The storage modulus and complex viscosity slightly decreased after the addition of vPOSS, but significantly increased after the addition of ePOSS, indicating the higher melt elasicity and broader processing window of the PLA/PBSA after the addition of ePOSS. The chloroform solutions of PLA/PBSA/ePOSS composites were turbid in appearance, and the extracted POSS showed absorbant peaks assigned to the vibration of OH and CO groups in the Fourier transform infrared spectroscopy analysis, indicating the reactions between ePOSS and the PLA/PBSA. Polarized optical microscopy analysis revealed that the two types of POSS could act as nucleating agents for PLA, and enhance its crystallization ability. Thermal gravimetric analysis showed that the addition of the two types of POSS increased the decomposition temperature and activation energy, consequently retarding the thermal degradation of PLA/PBSA. The retardation of degradation is more significant with the addition of ePOSS, for the reactions reduced the end groups of PLA/PBSA as well as the molecular chain mobility. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci 2009

Effect of POSS™ functionality on morphology of thin hybrid chitosan films

—Organic-inorganic hybrid films based on chitosan (Chi) and hydrophilic polyhedral oligomeric silsesquioxanes (POSS™) were prepared by alkaline precipitation of the dried blends. The effect of the POSS type and concentration on morphology and permeability of Chi/POSS hybrid films were evaluated by IR spectroscopy, solid phase NMR, SEM and AFM and by diffusion transport of low-molecular-weight electrolytes. In mechanically stable hybrid films, contents of octakis{[3-(2,3- dihydroxypropoxy)propyl]dimethylsilyl}-POSS™ (DL-POSS), octakis(trimethylammonium)-POSS™ (TMA-POSS) and octaammonium-POSS™ (OA-POSS) range between 0.625 and 2.5 mol% (in relation to amount of the deacetylated chitosan amino groups). The large POSS molecules (approx. 2–3 nm) influenced the packing the chitosan chains on a nanoscale due to multiple intermolecular bonds and changed the heterogeneity of hybrid films. The electrolyte (HCl, NaCl and NaOH) transport through the films depended on the POSS type, its content, and the preparation method. With increasing POSS content, the permeabilities tended to increase across the hybrid films with the crosslinker (ethyleneglycol diglycidyl ether, 75 mol%), which was added into a precursor film before its drying and alkaline treatment. In contrast, the electrolyte penetration usually decreased through the films cross-linked after their drying and alkaline precipitation. The dependence of the diffusion permeability of Chi/POSS hybrid films on their morphology is discussed.