Octavinyl Polyhedral Oligomeric Silsesquioxane Research Articles

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).

Processing and Characterization of UV Irradiated HDPE/POSS Fibers.

High-performance polyethylene fibers, renowned for their superior attributes encompassing a high strength, modulus, and lightness, are conventionally manufactured through the gel spinning method. However, this method is encumbered by several drawbacks, including the requisite application of a separate process to eliminate solvents from the fibers and the utilization of chemicals deleterious to both the environment and human health. Alternatively, the adoption of the melt spinning method presents a cleaner and environmentally friendly approach to attain high-performance fibers. In the present investigation, high-density polyethylene (HDPE) fibers were produced employing the melt spinning method. After the spinning process, strategic orientation procedures were implemented to enhance the crystallinity of the spun fibers. As a concluding step, seeking to elevate the overall performance of the oriented spun HDPE fibers, a cross-linking treatment was applied via UV irradiation. Notably, this study pioneers the incorporation of polyhedral oligomeric silsesquioxane (POSS) hybrid nanoparticles into HDPE during melt spinning, presenting a novel advancement aimed at further enhancing the mechanical properties of oriented HDPE fibers during UV irradiation. For this purpose, two distinct types of POSS, namely octavinyl POSS (OVPOSS) and methacryl POSS (MACPOSS), both having unsaturated double bonds capable of participating in the network structure of oriented HDPE spun during UV cross-linking, were used. The thermal, morphological, and mechanical properties, as well as the crystal structure of samples with and without POSS molecules, were investigated. The mechanical properties of the fibers exhibited higher values in the presence of OVPOSS. The incorporation of OVPOSS and MACPOSS resulted in a noteworthy improvement in the material's tensile strength, exhibiting a marked increase of 12.5 and 70.8%, respectively. This improvement can be attributed to the more homogeneous dispersion of OVPOSS in HDPE, actively participating in the three-dimensional network structure. After orientation and UV irradiation, the tensile strength of HDPE fibers incorporating OVPOSS increased to 293 MPa, accompanied by a concurrent increase in the modulus to 2.8 GPa. The addition of POSS nanoparticles thus yielded a substantial improvement in the overall performance of HDPE fibers.

Controllable synthesis of 3D superhydrophilic Cd(II) ion-imprinted polymer microspheres based on OV-POSS and bifunctional monomers synergy with superior selectivity for Cd(II) adsorption

Novel 3D porous Cd(II) ion-imprinted polymer (Cd(II)-IIP) microspheres based on octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization technique combined with the synergistic effect of N-hydroxymethylacrylamide (NMA) and 1-vinylimidazole (1-VI) as bifunctional monomers. RAFT polymerization could achieve a controllable synthesis of polymer networks on OV-POSS. The structure, composition and properties of Cd(II)-IIP were systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscope, water contact angle and thermogravimetric analysis. The results showed that the adsorbent, with a water contact angle of 0 ° and superhydrophilicity, has a high potential for application in aqueous phase systems. Different parameters influencing the sorption performance of Cd(II)-IIP, such as OV-POSS ratio, functional monomers ratio, adsorbent dosage, pH and adsorption time were optimized. Under optimal conditions, the maximum adsorption amount of Cd(II)-IIP for Cd(II) was 80.21 mg/g, and the adsorption equilibrium state could be reached within 40 min. The sorption kinetics proved that the sorption was chemisorption and the rate-limiting step was intraparticle diffusion. Thermodynamic studies showed that Cd(II) sorption was a spontaneous endothermic process. Importantly, XPS analysis, density functional theory (DFT) and frontier molecular orbital (FMO) theory calculations showed that the sorption of Cd(II)-IIP was attributed to the coordination of O and N atoms with Cd(II) on NMA and1-VI, respectively. Actual water sample analysis results indicated that Cd(II)-IIP was an adsorbent of great application potential.

Synthesis of Carboxymethyl Cellulose-Acrylate-OvPOSS Graft Copolymer and its Application in Paper Protection

As an important part of cultural heritage, paper cultural relics have important historical, scientific and humanistic values. However, a large number of paper cultural relics are suffering from aging, mildew, yellowing, cracks, embrittlement and other threats, or are even completely damaged. To enhance the strength of paper cultural relics and prolong the life of paper cultural relics, a novel CMC-acrylate-OVPOSS graft copolymer was synthesized with carboxymethyl cellulose (CMC), methyl methacrylate (MMA), butyl acrylate (BA), hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), octavinyl polyhedral oligomeric silsesquioxane (OVPOSS). The synthesized materials were analyzed by infrared spectroscopy, X-ray diffractometer, thermal analyzer and X-ray photoelectron spectroscopy. In addition, the reinforcement solution was coated on the surface of the paper, and the protective effect of the reinforcement solution on the paper was evaluated by testing the mechanical and optical properties of the paper. When the reinforcement solution with a mass concentration of 10 % was coated on the paper, the mechanical properties of the paper were greatly improved, and the gloss and whiteness were basically unchanged.

Novel and eco-friendly hydrophobic treatment of cotton and polyester fabrics based-on octavinyl and aminopropylisobutyl polyhedral oligomeric silsesquioxanes (OL-POSS and AM-POSS)

The hydrophobicity of cotton and polyester fabrics plays a significant role in various industrial applications. Anchoring hydrophobic chemicals onto the fabric surface is one of the major strategies. Fluorinated chemicals are widely employed to construct hydrophobic surfaces. However, alternative hydrophobic coatings are urgently sought by researchers due to the potential risks and hazards of fluorinated chemicals. Polyhedral oligomeric silsesquioxanes (POSS) are one of the most potential alternatives as they increase the roughness and lower the surface energy through chemical enhancement of the surface. In this work, hydrophobic cotton and polyester surfaces were fabricated anchoring Octavinyl POSS (OL-POSS) and Aminopropylisobutyl POSS (AM-POSS) onto the surface via one-step dip-coating technique. To enhance the surface roughness and the hydrophobicity, Ultraviolet (UV) radiation was employed with Benzoyl Peroxide (BPO) initiator. Water contact angle (WCA) of both fabrics increased from 0° to 136° using 5% POSS coatings with initiator and UV present. Water absorption duration (WAD) also increased from several seconds up to 310 min. Furthermore, 5% POSS modified fabrics gave similar or better WAD values when compared to coatings treated with fluorinated chemicals. The findings confirmed that OL-POSS and AM-POSS coatings are eligible environmentally friendly candidates for the replacement of fluorinated chemicals.

Synergistically toughened epoxy resin based on modified-POSS triggered interpenetrating network

The toughening of epoxy resin has always been one of the key topics in the researches about high-performance matrix used for advanced composites. Up to now, single-property enhancement is usually accompanied by some compromises of other properties. This work constructed a novel in-situ interpenetrating network (IPN) structure composed of epoxy resin and vinyl ester resin (VER), along with modified octavinyl polyhedral oligomeric silsesquioxane (EPOSS) as the toughening core. In the present resin system, the VER component was firstly introduced to form IPN structures without phase separation to bring the improvement of overall strength and plastic deformation capacity. Moreover, the EPOSS could realize nano-scale dispersion in the resin matrix through the chemical reactions, which acted as the trigger of plastic shear deformation toughening under particle debonding. The side chains' physical entanglement of EPOSS played the key role in maintaining a balance between toughness and mechanical strength. With only 2 wt% of EPOSS, the optimal increase in impact toughness reached 139.6%, in addition to the 17.9% improvement of tensile strength and 9.0% enhancement of Young's modulus.

Synthesis and characterization of a novel double network hydrogel based on gellan‐gum crosslinked by octavinyl polyhedral oligomeric silsesquioxane for heavy metal removal

AbstractIn this study, we demonstrated a new design technique for producing DNNH based on gellan‐gum crosslinked by octavinyl polyhedral oligomeric silsesquioxane. Incorporating OV‐POSS nanoparticles as cross‐linkers into the first and second networks created strong coordination contacts and improved mechanical performance with 90% water. pH and contact time affect DNNH swelling, Ni(II), and Pb(II) removal. The resulting hydrogels were characterized by FT‐IR, SEM, XRD, and TGA analyzes. The capacity of the hydrogel to adsorb Ni(II) and Pb(II) is 213.66 and 132.55 mg/g, respectively, according to the adsorption isotherm model. The usefulness of kinetic and isotherm investigations, notably the pseudo‐second‐order model and the Langmuir model, for the adsorption of the aforementioned contaminants, was proven. Ni(II) and Pb(II) adsorption is spontaneous and endothermic, according to the study. The hydrogel's adsorption–desorption reusability was renewed five times. As a consequence, the generated hydrogel is recognized as a good adsorbent for aqueous Ni(II) and Pb(II) adsorption.

POSS-based polyionic liquids for efficient CO2 cycloaddition reactions under solvent- and cocatalyst-free conditions at ambient pressure.

The conversion of CO2 into value-added chemicals has become an imminent research topic and the cycloaddition of CO2 with a C1 resource to produce cyclic carbonates is a promising pathway for CO2 utilization. Herein, a series of POSS-based polyionic liquids (PILs) were synthesized by the copolymerization of octavinyl polyhedral oligomeric silsesquioxane (POSS) with an imidazolium ion linker. The prepared PILs have the characteristics of hydrogen bond donors, halogen atom sites, stable pore structures, and thermal stability, and are used as heterogeneous catalysts for the cycloaddition of epoxides with carbon dioxide. The effect of linkers on the cycloaddition is investigated by tuning the ratio of POSS units to imidazolium ions. Under the optimized conditions, the conversion of epichlorohydrin can reach 99.18% at atmospheric pressure with neither co-catalysts nor solvents. It is concluded that the reaction of the cycloaddition of epoxides with carbon dioxide follows pseudo-first-order kinetics. Moreover, the presence of the catalysis of PILs leads to a significant decrease in the activation energy barrier for cycloaddition. The catalyst can be facilely recovered due to its high stability, and only a slight decrease in conversion was observed after five successive runs. In addition, the mechanism of PILs catalyzing the cycloaddition reaction of epoxides with CO2 is proposed. This work not only provides a sustainable and green process for CO2 cycloaddition, but also highlights the potential of using PILs for CO2 utilization.

Boronate Avidity Assisted by Dendrimer-like Polyhedral Oligomeric Silsesquioxanes for a Microfluidic Platform for Selective Enrichment of Ubiquitination and Glycosylation.

A new strategy of improving boronate avidity with good accessibility of sites was suggested by utilizing a dendrimer-like structure of boron materials based on octavinyl-polyhedral oligomeric silsesquioxanes (Ov-POSS). 3-(Acrylamido)phenylboronic acid (AAPBA) was used as a functional monomer and ethylene glycol dimethacrylate (EDMA) and Ov-POSS as cross-linkers. The resulting Ov-POSS cross-linked boron monolith exhibited 27 times stronger affinity for glycoproteins than the Ov-POSS-free monolith. Importantly, the bonding strength of the poly(AAPBA-co-Ov-POSS-co-EDMA) monolith to the glycoproteins with multiple sugars, horseradish peroxidase (HRP) was 4 orders of magnitude higher than that of the single cis-diol-containing compound. The resulting monolith was used as a part of a microfluidic platform for online processing of the protein extracts from mouse liver, which integrated five functions, including protein grading, denaturation, enzymatic hydrolysis, and enrichment of glycopeptides and ubiquitin-modified peptides. The sample processing time can be reduced by nearly half compared to the offline method. Moreover, 86.7% of glycopeptides and 75% of glycoproteins were newly identified after treatment. All of the results indicated that the synergistic strategy of Ov-POSS cross-linking can significantly improve trace glycosylation's binding capacity and enrichment performance. The microfluidic platform developed may provide a promising technical tool for automated, high-efficiency, high-throughput analysis for post-translational modification proteomics.

Synthesis of octavinyl polyhedral oligomeric silsesquioxane (ovi‐POSS) based organic/inorganic hybrid resin microspheres for rapid and efficient oils absorption

AbstractIn this work, a hybrid nanocomposite of poly(styrene‐co‐butyl acrylate‐co‐dodecyl acrylate) and octavinyl polyhedral oligomeric silsesquioxane (ovi‐POSS) was synthesized by suspension polymerization and the composite resin was characterized by Fourier transform infrared, scanning electron microscopy energy‐dispersive spectrometer and thermal gravimetric analysis. The effects of ovi‐POSS content on the oil absorbency of hybrid composite resin were investigated. The results indicated that the maximum saturated oil absorption rate of sample PSBLA/ovi‐POSS‐1 with 1 wt% ovi‐POSS content toward four oils and organic solvents (toluene, xylene, gasoline, and diesel) are, respectively, 20.51, 18.56, 12.48, and 7.03 g g−1, and the process taken just about 5 min. The absorption kinetic model fitting proved that the adsorption behavior of the four oils on PSBLA/ovi‐POSS‐1 resin microspheres was dominated by the physical adsorption. Besides, PSBLA/ovi‐POSS‐1 has good oil retention rate (stay over 95% after centrifuging at 3000 rpm for 5 min) and reusability (for 12 times). These excellent oil absorption performances are attributed to the loose network structure of the composite resin. The rapid and efficient oils absorption properties give the composite resin potential practical applications in many areas.

Multielement Flame-Retardant System Constructed with Metal POSS-Organic Frameworks for Epoxy Resin.

The direct coordination between polyhedral oligomeric silsesquioxane (POSS) and Co forms an assembly of nanoparticles with low specific surface area and leads to a poor dispersion state in the epoxy resin matrix, resulting in unsatisfactory flame-retardant efficiency. Metal-organic frameworks (MOFs), for instance, ZIF-67, provide not only the cobalt element but also the porous framework that endows the nanocomposite of MOFs and POSS with high specific surface area and abundant Co sites in the silica skeleton. Herein, ZIF-67 is hybridized with octacarboxyl POSS, resulting in the removal of the alkaline ligand to form novel metal POSS-organic frameworks (MPOFs). The size differences for organic groups and silica nanocages of POSS vs. micropores of ZIF-67 gave rise to a reverse click reaction, reforming octavinyl POSS isolated on the outer surface of the Co complex, which could be further modified by a phosphorous flame retardant using an addition reaction. The obtained MPOFs-P with 2 wt % loading in epoxy resin could improve the limiting oxygen index value of the composites to 27.0% and pass the V-0 rating in the UL-94 test. Meanwhile, the peaks of the heat release rate and especially the total smoke production were reduced by 46.6 and 25.2%, respectively. The robust char layer reduces the emission of toxic gas CO by 39.8%. The above epoxy product with promising flame retardancy also improved mechanical properties, thanks to the filler with a unique nanostructure. The ingenious work offers enlightenment for the hybridization method of MOFs and POSS to fabricate a multielement flame-retardant system for epoxy resin with high efficacy.

ABC-Type, Bola-Form Giant Surfactants: Synthesis and Self-Assembly.

Due to the fast phase separation kinetics and small feature size, the self-assembly of giant molecules has attracted lots of attention. However, there is not much study on multicomponent giant surfactants. In this work, through a modular synthetic strategy, different polyhedral oligomeric silsesquioxane (POSS)-based molecular nanoparticles are installed with diverse functionalities (hydrophobic octavinyl POSS (VPOSS), hydrophilic dihydroxyl-functionalized POSS (DPOSS), and omniphobic perfluoroalkyl-chain-functionalized POSS (FPOSS)) on the ends of one polystyrene (PS) chain to build up a series of triblock bola-form giant surfactants denoted as XPOSS-PSn -FPOSS (X represents V or D). The target molecules are prepared by a combination of atom transfer radical polymerization (ATRP), esterification, as well as Cu(I)-catalyzed azide-alkyne cycloaddition(CuAAC) and thiol-ene "click" reactions. These macromolecules are thoroughly characterized by combined technologies including nuclear magnetic resonance(NMR), size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. It is revealed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) that VPOSS-PSn -FPOSS adopts a two-phase separation scenario where VPOSS and POSS are segregated in one phase. DPOSS-PSn -FPOSS with a third hydrophilic DPOSS shows a three-phase separation scenario, where highly ordered phase structures are difficult to develop owing to the competition of mutual phase separation processes and may be trapped in kinetically metastable states.

Application of carboxymethyl cellulose-acrylate-OVPSS graft copolymer emulsion in paper reinforcement and protection

Abstract Paper cultural relics are both precious, inheritable and fragile. However, with the passage of time, paper will also be affected by a variety of factors, and will appear mildew, yellow, brittle, or even completely damaged. In order to protect the cultural relics, extend lifespan paper, CMC-acrylate-OVPOSS graft copolymerization emulsion was synthesized by using carboxymethyl cellulose (CMC) as substrate, methyl methacrylate (MMA), butyl acrylate (BA), glycidyl methacrylate (GMA), hydroxyethyl methacrylate (HEMA), octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) as graft copolymer. The CMC-acrylate-OVPOSS emulsion was coated on the surface of the paper to test its protective effect on the paper. The results showed that the mass concentration of 10 % reinforcement solution coated on the paper, mechanical properties of paper were greatly improved, and the gloss and whiteness of paper were slightly changed, the paper also had a certain aging resistance and acid and alkali corrosion resistance. At the same time, the reversibility experiment showed that the reinforcement material had a certain reversibility.

Hierarchically-structured superhydrophobic POSS/PVDF composite membrane for anti-fouling and anti-wetting membrane distillation

Membrane fouling and wetting were two unsolved issues for membrane distillation (MD), fostered an enduring pursuit of well-designed superhydrophobic membrane. In this work, a novel hierarchically-structured superhydrophobic membrane was prepared by grafting octavinyl-polyhedral oligomeric silsesquioxane (OVPOSS) onto polyvinylidene fluoride (PVDF) membrane via UV-induced thiol-ene click reaction after the hydroxylation and sulfhydrylation pretreatment. The POSS/PVDF membrane exhibited high roughness and superhydrophobicity, and the pore structure was optimized with smaller size but centralized distribution. For the fabricated superhydrophobic membrane with low sliding angle (about 7.5°), the maintaining of Cassie-Baxter state and the “slip effect” significantly mitigated membrane fouling and wetting, due to the retardation of the liquid invasion into the gas-solid interface. It was found that scaling was the leading fouling for the commercial PVDF membrane, and the interaction between Ca2+ and carboxyl was the main organic fouling mechanism. While for the POSS/PVDF membrane, organic fouling via hydrophobic-hydrophobic interaction was the main membrane fouling and the scaling was significantly alleviated. The fabricated POSS/PVDF composite membrane had significant superiority over commercial PVDF membrane, which showed promising potential in challenging wastewater treatment. Additionally, this work also offered a new and facile method for superhydrophobic membrane fabrication.

Thermally highly stable polyhedral oligomeric silsesquioxane (POSS)-sulfur based hybrid inorganic/organic polymers: synthesis, characterization and removal of mercury ion

Elemental sulfur was copolymerized with octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) cages in diglyme solution via the inverse vulcanization method and characterized using NMR and FTIR spectroscopic techniques.

Octavinyl polyhedral oligomeric silsesquioxane on tailoring the DC electrical characteristics of polypropylene

This work reports the effect of octavinyl polyhedral oligomeric silsesquioxane (OvPOSS) on tuning the electrical performance of polypropylene (PP). OvPOSS with different content are introduced into PP using the solution method. The microstructural morphology, crystallinity behaviour, breakdown strength, DC conductivity, space charge formation, and trapping level distribution are measured. The results indicate that the OvPOSS nanofiller can be dispersed uniformly with a doping content of 2.0 phr or less. The DC conductivity is decreased, and the breakdown strength of OvPOSS/PP nanocomposites is significantly increased. The space charge accumulation of the OvPOSS/PP nanocomposites is significantly suppressed due to the introduction of deeper traps by the OvPOSS nanofiller. Finally, the experimental results demonstrate that the OvPOSS nanofiller can greatly increase the electrical performance of the base PP and the OvPOSS/PP nanocomposites have much potential for HVDC applications. They further demonstrate that the PP is environmental-friendly due to its thermo-plastic property, which can be recycled after the manufacture.

Polypropylene/Lignin/POSS Nanocomposites: Thermal and Wettability Properties, Application in Water Remediation.

Compositing is an interesting strategy that has always been employed to introduce or enhance desired functionalities in material systems. In this paper, sponges containing polypropylene, lignin, and octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) were successfully prepared via an easy and elegant strategy called thermally induced phase separation (TIPS). To fully explore the behaviour of different components of prepared sponges, properties were characterized by a thermogravimetric analyser (TGA), differential scanning calorimetry (DSC), Fourier transform infrared measurement (FTIR), and scanning electron microscopy (SEM). Furthermore, wettability properties toward an organic liquid and oil were investigated. The FTIR analysis confirmed the chemical modification of the components. TGA and DSC measurements revealed thermal stability was much better with an increase in OV-POSS content. OV-POSS modified sponges exhibited ultra-hydrophobicity and high oleophilicity with water contact angles of more than 125°. The SEM revealed that POSS molecules acted as a support for reduced surface roughness. Moreover, OV-POSS-based blend sponges showed higher sorption capacities compared with other blend sponges without OV-POSS. The new blend sponges demonstrated a potential for use as sorbent engineering materials in water remediation.

Organic Inorganic Materials Open New Path for Synthesis and Application

Hybrid smart materials, frame both inorganic and organic components, and their contribution in the designing of specific modern technologies are receiving more attention and interest due to their better improved solution process, controllable synthesis, and tunable chemical roperties. However, the focus problem of compatibility, solubility and aggregation is to be solved urgently, which inevitably limits them widely application. To this end, an inorganic–organic hybrid material with wide-band absorption is designed and prepared, that incorporates octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS)with aminecontaining and cyan uric chloride (CC) to get our novel system OV-POSS-Amine-CC our structure, composition, and properties were characterized and evaluated, the system was prepared as anew path to synthesis novel enhanced hybrid to applied in many application.

Crosslinked Low-Density Polyethylene/Polyhedral Oligomeric Silsesquioxanes Composites: Effects of Crosslinker Concentration on the Mechanical, Thermal, Rheological, and Shape Memory Properties

The aim of this study was to produce crosslinked low-density polyethylene (LDPE) composites using peroxide and octavinyl polyhedral oligomeric silsesquioxane (OvPOSS) and to examine the shape memory behavior. The strategy was to use OvPOSS as a coagent to increase the crosslinking density and crosslinking efficiency while improving the mechanical and shape memory properties as well. The peroxide concentration, from 0.5 phr to 3.0 phr, was taken as the experimental parameter, with 4 phr OvPOSS added to all composites. The melt mixing route was applied similar to that which would be used industrially. The thermo-responsive shape memory properties near the melting point were examined in tension mode. The dispersion of OvPOSS in the LDPE matrix was observed via scanning electron microscopy and Si-mapping. In addition, the thermal, mechanical, structural, and rheological features of the novel LDPE/OvPOSS and LDPE/peroxide/OvPOSS systems were investigated. It was observed that the crosslinking density of LDPE increased in the presence of OvPOSS, which affected the mechanical, rheological and thermal properties and increased the shape recovery ratio of the LDPE.

Surface modification of polyurethane/HCNT nanocomposite with octavinyl polyhedral oligomeric silsesquioxane as a heart valve material

Surface properties of octavinyl polyhedral oligomeric silsesquioxane (OVS), grafted polyurethane (PU) and heparinized carbon nanotubes (HCNTs) nanocomposite thin-films were evaluated, and the effect of OVS presence on platelet adhesion on the surface of nanocomposite films for artificial heart valve application was investigated using in-vitro tests. OVS was synthesized, then PU and CNT (PU/CNT) nanocomposite films were dipped in the solution of OVS in toluene for grafting. Synthesized OVS was investigated by XRD, FTIR, and NMR tests. SEM-EDX micrographs showed that the morphology of the PU/HCNT surface was obviously changed due to OVS grafting. Surface studies proved OVS grafting on the surface. Surface roughness was increased after grafting PU/HCNT surface with OVS in comparison to the untreated PU/HCNT nanocomposite surface. The contact angle was increased from 88° for PU/HCNT sample to 165° for OVS-grafted PU/HCNT sample. After the addition of CNTs to the matrix, the modulus was increased. According to the MTT test, modified polymeric nanocomposite has no cytotoxicity, and the adhesion of L929 fibroblast cells on the grafted surface was increased. Its shown in the platelet adhesion test that blood compatibility of the OVS grafted films are increased in comparison with PU/HCNT. Surface calcification of OVS-grafted PU/HCNT was reduced according to the in-vitro calcification test. It has been concluded that the combination of physical and mechanical properties of PU/HCNT and the calcification resistance of OVS is a suitable achievement for heart valve application.