Trisilanolisobutyl Polyhedral Oligomeric Silsesquioxane Research Articles

Fabrication of Liquid Crystalline Polyurethane/Polyhedral Oligomeric Silsesquioxane Nanofibers via Electrospinning

A series of fibrous meshes based on liquid crystalline polyurethane/POSS composites were prepared. Two types of polyhedral oligomeric silsesquioxanes (POSSs) of different structures were chosen to show their influence on electrospun fibers: aromatic-substituted Trisilanolphenyl POSS (TSP-POSS) and isobutyl-substituted Trisilanolisobutyl POSS (TSI-POSS) in amounts of 2 and 6 wt%. The process parameters were selected so that the obtained materials showed the highest possible fiber integrity. Moreover, 20 wt% solutions of LCPU/POSS composites in hexafluoroisopropanol (HFIP) were found to give the best processability. The morphology of the obtained meshes showed significant dependencies between the type and amount of silsesquioxane nanoparticles and fiber morphology, as well as thermal and mechanical properties. In total, 2 wt%. POSS was found to enhance the mechanical properties of produced mesh without disrupting the fiber morphology. Higher concentrations of silsesquioxanes significantly increased the fibers’ diameters and their inhomogeneity, resulting in a lower mechanical response. A calorimetric study confirmed the existence of liquid crystalline phase formation.

Effect of trisilanol isobutyl polyhedral oligomeric silsesquioxane (TPOSS) in recycled PET (rPET) and polypropylene based compound: Investigation on mechanical properties

Recycled polyethylene terephthalate is successfully prepared. This project is involved for “Circular economy” policy. It is successfully prepared into powder form by nano-grinder technique. 10 phr of PP-g-MA and 1 phr to 5 phr of TPOSS are added for compatibilizer and mechanical properties enhancement, respectively. PP-g-MA can form the chemical linkage of the anhydride groups with the polyamide end groups. 20 wt% of recycled polyethylene terephthalate powder and polypropylene based compound is successfully fabricated by melt mixing. Then, it is fabricated by melting spinning technique. Fourier transform infrared presents Si-O-Si linkage in binary blend compound. X-ray diffraction pattern reports that single phase is obtained. Adding TPOSS can be induced to crystallinity enhancement. No significant change of thermal properties was observed from room temperature to 300℃. Scanning electron microscope reports that with the PP-g-MA provides smoothness of surface. Recycled polyethylene terephthalate is uniformly distributed. Melting and crystallization temperatures are reported to be 162℃ to 167℃ and 115℃ to 120℃, respectively. All of throughput rate is reported to be 1.8 g⸳min-1 to 2.3 g⸳min-1. With the existence of TPOSS, the mechanical properties of compound are slightly increased. TPOSS are added for mechanical properties enhancement. The polymer compound presents the excellent properties. It is remarkable to note that recycled polyethylene terephthalate is considered as an excellent candidate for use as raw material for polymer compound production.

Creep, recovery, and stress relaxation behavior of nanostructured bioactive calcium phosphate glass-POSS/polymer composites for bone implants studied under simulated physiological conditions.

The creep and recovery and the stress relaxation behaviors of poly(butylene adipate-co-terephthalate) (PBAT) and polyhydroxyalkanoates (PHA) binary blends incorporating 30 wt % of a mixture of trisilanolisobutyl polyhedral oligomeric silsesquioxanes (POSS) and calcium phosphate glass (CaP-g) were investigated under simulated physiological and human body temperature conditions. The synergistic effect of PHA and CaP-g/POSS filler remarkably improved the creep behavior of the PBAT matrix and decreased its residual strain, consequently enhancing its elastic recovery. A considerable increase of the relaxation modulus of the hybrid materials was also observed upon incorporation of PHA and CaP-g/POSS. The relaxation modulus of the neat PBAT sample increased from ~60 MPa to ~1600 MPa after addition of 30 wt % CaP-g/POSS and 70 wt % PHA. However, after exposure of the composites to the simulated human body conditions for 14 days, a drop of dynamic mechanical properties of the studied material systems was observed along with formation of a desirable calcium phosphate phase on the material surface. The long-term (i.e., up to 7 × 105 s) viscoelastic behavior of the studied materials was successfully predicted using the time-temperature superposition principle and the obtained creep strain and the relaxation modulus master curves were satisfactorily fitted to the Findley power law equation and the generalized Maxwell model, respectively. This study demonstrates a facile method for tailoring CaP-g/POSS bioactive glasses composition for bone-like apatite formation on biopolymer surfaces. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2419-2432, 2019.

Effect of different POSS structures on the crystallization behavior and dynamic mechanical properties of biodegradable Poly(ethylene succinate)

The effect of different polyhedral oligomeric silsesquioxanes (POSS) structures on the crystallization behavior and dynamic mechanical properties of biodegradable poly(ethylene succinate) was investigated in this work. Two kinds of POSS molecules with different structures, i.e., trisilanolisobutyl-polyhedral oligomeric silsesquioxanes (tsib-POSS) with an open cage structure and octaisobutyl-polyhedral oligomeric silsesquioxanes (oib-POSS) with a close cage structure, were separately incorporated into PES matrix at the same low loading of 1 wt%. Both types of POSS dispersed finely in the matrix, with the size of tsib-POSS aggregates being smaller than that of oib-POSS aggregates, which was in agreement with the solubility parameter difference between the two types of POSS molecules and PES matrix. The crystallization processes of PES under different conditions were accelerated by both types of POSS; moreover, oib-POSS showed stronger acceleration effect than tsib-POSS probably due to the good lattice matching between PES and oib-POSS. The crystallization mechanism and crystal structure remained unchanged for PES in the composites, despite the type of POSS. Tsib-POSS remarkably increased the storage modulus of PES, while oib-POSS slightly decreased the storage modulus of PES.

Structural factor of nanoparticles in the stress-induced crystallization of poly(ethylene terephthalate)

The crystallization behavior of poly(ethylene terephthalate) (PET) nanocomposites with clay and trisilanol isobutyl-polyhedral oligomeric silsesquioxane (TPOSS) in the high-speed spinning process was investigated in terms of take-up speed and content of nanoparticles. The spherical TPOSS promoted the crystallization of PET. On the other hand, the plate-like clay with the aspect ratio of 250 suppressed it. At the take-up speed of 3.5 km/min, the crystallinity of the PET nanocomposite containing 1 wt% of clay was 23%, much lower than 48% of neat PET and 57% of the PET nanocomposite containing 2 wt% of TPOSS. The 2D-WAXS analysis revealed that the anisotropic clay nanoparticles aligned parallel to the fiber axis even in the fiber prepared from the free-fall spinning process. Increasing the take-up speed of spinning further increased the degree of orientation of the particle. Because of the suppressed crystallization of PET by the highly oriented clay nanoparticles, the fiber of the PET/clay nanocomposite did not give any characteristic 2D-SAXS pattern over the take-up speed range examined, indicating the absence of tilted lamellar stacks. In the fibers of neat PET and PET/TPOSS nanocomposites, however, an X-shaped 4-point pattern was obtained at low take-up speeds, which was converted to the scattering pattern of an equatorial streak with the inverse triangular scatterings in the meridional direction at high take-up speeds. The transition of the 2D-SAXS pattern shape took place at the take-up speed of 4.5 km/min for neat PET which was shifted to the lower speeds of 4 and 3.5 km/min by adding 1 and 2 wt% of TPOSS, respectively.

CO2 removal using membrane gas absorption with PVDF membrane incorporated with POSS and SAPO-34 zeolite

The mixed matrix membranes designed with enhanced affinity for CO2 by incorporating the gas selective fillers are studied in this work. Polyhedral oligomeric silsesquioxane (POSS) and SAPO-34 zeolite were selected to engineer the additional pathway for CO2 diffusion in polyvinylidenefluoride (PVDF) membrane in order to improve the CO2 removal via membrane gas absorption (MGA). The double-soft coagulation resulted in the neat PVDF membrane (M-0) with a mean pore size of 2.77±0.09μm and a water contact angle of 137.5°. M-S34 membrane with the hydrophilic SAPO-34 zeolite and M-AP membrane with aminopropylisobutyl POSS exhibited the smaller pore size and lower water contact angle than the neat membrane. Although the mean pore size of M-SP membrane with trisilanolisobutyl POSS (0.54±0.06μm) is small in comparison to M-0 membrane, it showed the similar water contact angle of 132.4 ° to M-0 membrane. The reduction of pore size could be related to the fast coagulation caused by different interactions between polymer, filler, solvents and non-solvents. Nevertheless, the blending of trisilanolisobutyl POSS into M-SP membrane still improved the CO2 absorption flux which is more than 2 times higher than the neat membrane. The functionality of SAPO-34 and aminopropylisobutyl POSS in the PVDF membranes was limited by the low pressure and membrane morphology, respectively.

The Influence of Trisilanolisobutyl POSS on Domain Microstructure of a Polyurethane Hybrid Composite: A Molecular Simulation Approach

A molecular dynamics simulation approach was adopted to investigate the domain microstructure of polyurethane (abbreviation PU) hybrid compositeswith trisilanolisobutyl polyhedral oligomeric silsesquioxane (abbreviation TSI-POSS) covalently bonded to polymer chains. The accuracy of models and force field has been verified by wide-angle X-ray scattering and volume-temperature behavior analysis. TheWAXS results indicate that with TSIPOSS concentration increasing in PU hybrid composites, distinct crystallite clusters are formed which increase the volume of hard segments and lead to the microphase separation. Furthermore, details of chain packing have been evaluated by radial distribution function, which shows that below 13wt% TSI-POSS concentration, the number of contacts between neighboring chains is decreased due to the prominent cage of TSI-POSS. However, when TSI-POSS concentration is up to 22wt%, the number of contacts is increased because the formation of crystallite cluster pulls neighboring chains closer to each other and significantly shortens their distance. The mobility of the TSI-POSS cores and PU composite backbones has been determined by the mean square displacement. The result reveals that the incorporation of TSI-POSS as the rigid core in the polymer backbone apparently restricts motions of the surrounding chains, which is also supported by volume-temperature behavior analysis as the glass transition temperature of PU composites increases with rising TSI-POSS concentration.

Thermal and mechanical properties of liquid‐like trisilanol isobutyl‐polyhedral oligomeric silsesquioxanes (POSS) derivative/epoxy nanocomposites

Liquid‐like trisilanol isobutyl polyhedral oligomeric silsesquioxanes derivative (L‐POSS‐D) was synthesized with γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) as corona and polyetheramine M1000 as canopy. Its structure and properties were characterized by FTIR, XPS, TGA and Rheology data. Epoxy nanocomposites with 0.0, 0.5, 1.0 and 2.0 wt% content of L‐POSS‐D were prepared. Tg of the nanocomposites improved 47.6°C higher than pure epoxy resin. Mechanical properties, including flexural strength and impact toughness, were improved markedly with L‐POSS‐D. The morphologies of impact fracture were studied by SEM. POLYM. COMPOS., 38:691–698, 2017. © 2015 Society of Plastics Engineers

Preparation and Characterization of Polyhedral Oligomeric Silsesquioxane-Containing, Titania-Thiol-Ene Composite Photocatalytic Coatings, Emphasizing the Hydrophobic-Hydrophilic Transition.

Coatings prepared from titania-thiol-ene compositions were found to be both self-cleaning, as measured by changes in water contact angle, and photocatalytic toward the degradation of an organic dye. Stable titania-thiol-ene dispersions at approximately 2 wt % solids were prepared using a combination of high-shear mixing and sonication in acetone solvent from photocatalytic titania, trisilanol isobutyl polyhedral oligomeric silsesquioxane (POSS) dispersant, and select thiol-ene monomers, i.e., trimethylolpropane tris(3-mercaptopropionate) (TMPMP), pentaerythritol allyl ether (APE), and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TTT). The dispersed particle compositions were characterized by DLS and TEM. The synthetic methods employed yield a strongly bound particle/POSS complex, supported by IR, 29Si NMR, and TGA. The factors of spray techniques, carrier solvent volatility, and particle size and size distributions, in combination, likely all contribute to the highly textured but uniform surfaces observed via SEM and AFM. Polymer composites possessed thermal transitions (e.g., Tg) consistent with composition. In general, the presence of polymer matrix provided mechanical integrity, without significantly compromising or prohibiting other critical performance characteristics, such as film processing, photocatalytic degradation of adsorbed contaminants, and the hydrophobic-hydrophilic transition. In all cases, coatings containing photocatalytic titania were converted from superhydrophobic to superhydrophilic, as defined by changes in the water contact angle. The superhydrophilic state of samples was considered persistent, since long time durations in complete darkness were required to observe any significant hydrophobic return. In a preliminary demonstration, the photocatalytic activity of prepared coatings was confirmed through the degradation of crystal violet dye. This work demonstrates that a scalable process can be found to prepare titania-thiol-ene coatings having improved coating properties which also exhibit photocatalytic and self-cleaning attributes.

Synthesis of liquid-like trisilanol isobutyl-POSS NOHM and its application in capturing CO2

The trisilanol isobutyl polyhedral oligomeric silsesquioxane(POSS) was fabricated into liquid-like nanoparticle organic hybrid materials(NOHMs) with γ-(2,3-epoxypropoxy)propytrimethoxysilane as corona and polyetheramine M2070 as canopy, and the product was called liquid-like POSS NOHM. The liquid-like POSS NOHM has a low viscosity at room temperature without any solvent and the mass fraction of trisilanol isobutyl POSS was 23.38%. The liquid-like POSS NOHM shows great CO2 capturing property with a capacity of 2.108 mmol/g(pCO2=6 MPa). The physical adsorption increased obviously with the pressure going up and it may make a difference between liquid-like POSS NOHMs and traditional monoethamolamine(MEA) based CO2 absorbent. The recycle property was also studied. The NOHM behaved as fresh product even after 10 cycles.

The Effect of Humping Semi-Enclosed Cage Structure on Polymer Chains Characteristics of TSI-POSS/PU Hybrid Composites

Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with the humping semi-enclosed cage structure, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4’-methylenebis (phenyl isocyanate) (MDI) and glycerol propoxylate to prepare TSI-POSS/PU hybrid composites, respectively. The polymer chain characteristics of these composites were investigated by wide angle X-ray scattering (WAXS) and molecular dynamics simulation approach. The results indicate that with TSI-POSS concentration increasing up to 22 wt% in hybrid composites, due to the humping semi-enclosed cage structure, distinct crystallite clusters are formed which lead to the micro-phase separation in composites. Meanwhile, the mobility of TSI-POSS cores and backbones in PU composites has been evaluated by the mean square displacement, which confirms that as the concentration of TSI-POSS increasing, the mobility of polymer chains are restricted apparently. Furthermore, it also indicates that the incorporation of TSI-POSS is as the rigid core in hybrid composites.

Effect of polyhedral oligomeric silsesquioxane and sorbitol on properties of isotactic polypropylene

Isotactic polypropylene(iPP) was modified by the introduction of polyhedral oligomeric silsesquioxanes(POSS) and 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol(DMDBS). Chemical combination of (3-mercapto)-propyl-heptaisobutyl POSS with DMDBS(POSS-DMDBS), and physical mixing of DMDBS with octaisobutyl POSS (iso-POSS/DMDBS) or trisilanolisobutyl POSS(tri-POSS/DMDBS) were applied respectively to modifying iPP, and the effects of POSS and DMDBS on crystallization, rheological and mechanical properties of iPP were systematically investigated. The results indicate that iso-POSS/DMDBS and tri-POSS/DMDBS were more effective than POSS-DMDBS on the improvement of the crystallization behavior of iPP due to the higher crystallization temperature, while the crystallinity of iPP containing POSS-DMDBS was enhanced, approximately approached to that of iPP containing tri-POSS/DMDBS. The tensile strength of iPP with POSS-DMDBS was significantly increased from 34 MPa to 40 MPa, as high as that of iPP with iso-POSS/DMDBS. The different effects caused by the specific interaction between POSS and DMDBS could possibly be applied in the modification of iPP.

Reversible monolayer-to-crystalline phase transition in amphiphilic silsesquioxane at the air-water interface.

We report on the counter intuitive reversible crystallisation of two-dimensional monolayer of Trisilanolisobutyl Polyhedral Oligomeric SilSesquioxane (TBPOSS) on water surface using synchrotron x-ray scattering measurements. Amphiphilic TBPOSS form rugged monolayers and Grazing Incidence X-ray Scattering (GIXS) measurements reveal that the in-plane inter-particle correlation peaks, characteristic of two-dimensional system, observed before transition is replaced by intense localized spots after transition. The measured x-ray scattering data of the non-equilibrium crystalline phase on the air-water interface could be explained with a model that assumes periodic stacking of the TBPOSS dimers. These crystalline stacking relaxes upon decompression and the TBPOSS layer retains its initial monolayer state. The existence of these crystals in compressed phase is confirmed by atomic force microscopy measurements by lifting the materials on a solid substrate.

Crystallite Cluster Structure Formation Resulting from Semi-Enclosed Cage Interaction in TSI-POSS/PU Hybrid Composites

Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with three hydroxyl functional groups pendent to a semi-enclosed cage, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4'-methylenebis (phenyl isocyanate) (MDI) and glycerol propoxylate to prepare TSI-POSS/PU hybrid composites as a heavy linking node in backbone, respectively. The domain micro-structures of these composites were investigated by FTIR, wide angle X-ray scattering (WAXS) and molecular dynamics simulation approach. The results indicate that with TSI-POSS concentration increasing in hybrid composites, distinct crystallite clusters are formed which increase the volume of hard segments and lead to the micro-phase separation. Meanwhile, details of chain packing has been evaluated by radial distribution function, which shows that below 13wt% TSI-POSS concentration, the number of contacts between neighboring chains is decreased due to the humping semi-enclosed cage of TSI-POSS units. However, when TSI-POSS concentration is up to 22 wt%, the number of contacts is increased because the formation of crystallite cluster pulls neighboring chains closer to each other and significantly shortens their distance.

Trisilanolisobutyl POSS/polyurethane hybrid composites: preparation, WAXS and thermal properties

Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with three hydroxyl functional groups pendent to an open cage, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4′-methylenebis(phenyl isocyanate) and glycerol propoxylate to prepare TSI-POSS–PU hybrid composites as a heavy linking node in polymer backbone, respectively. These composites were characterized by FTIR, wide-angle X-ray scattering (WAXS), dynamic mechanical analysis and thermogravimetry techniques. In WAXS profiles, above 22 wt% TSI-POSS concentration, the morphology of composite is significantly altered and distinct crystallite clusters are formed, which increase the volume of hard segment in polyurethane (PU) hybrid composite. As TSI-POSS concentration rises, the glass transition temperature (T g) of composites is increased while the decomposition temperature is slightly decreased due to the oxysensitive isobutyl groups in structure. Meanwhile, the activation energy of hybrid composites is nearly unchanged indicating that the formation of crystallite cluster, which restricts motion of surrounding chains, is the predominant effect in T g increasing. It can be concluded that the morphology and the thermal property of polyurethane can be tailored by TSI-POSS incorporation, whereas functional group in TSI-POSS structure is the decisive factor for the thermostability of designed composites.

Surface Modification and Reinforcement of Silica Aerogels Using Polyhedral Oligomeric Silsesquioxanes

This study evaluated polyhedral oligomeric silsesquioxane (POSS) molecules as useful, multifunctional reinforcing agents of silica aerogels. Silica aerogels have low-density and high surface area, although their durability is often compromised by the inherent fragility and strong moisture absorption behavior of the silica networks. POSS molecules carrying phenyl, iso-butyl, and cyclohexyl organic side groups, and several Si-OH functionalities were incorporated into silica networks via reactions between Si-OH functionalities in POSS molecules and silanes. Solid state (13)C and (29)Si NMR spectra established that greater than 90% of POSS molecules grafted onto silica networks and led to an increase in fractal dimensions. An almost 6-fold increase in compressive modulus was achieved with less than 5 wt % trisilanol phenyl POSS, and a 50-fold decrease in polarity with negligible changes in density were seen in aerogels modified with less than 5 wt % trisilanol isobutyl POSS.

Microstructure and Crystallization Kinetics of Polyurethane Thermoplastics Containing Trisilanol Isobutyl POSS

The synthesis of thermoplastic polyurethanes (TPU) from the reaction of a NCO group-containing prepolymer and 0, 1.14, 1.71, and 2.28 wt% of trisilanol isobutyl polyhedral oligomeric silsesquioxane (POSS) was carried out in an instrumented batch mixer. The samples were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). SEM analysis shows that the incorporation of POSS promoted strongly aggregation through physical interactions (formation of POSS-rich domains). Modifications in the TPU microstructure and the reduction in the crystal size were observed in the XRD diffractograms. The incorporation of POSS equally altered the TPU crystallization, and samples bearing higher concentrations of POSS formed two distinct types of crystalline structures. The kinetics of crystallization showed that nucleation strongly depends on the balance between TPU crystal formation and POSS-rich domains.