POSS nanoparticles as a potential compatibilizer for natural rubber/butadiene rubber blends

Octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) was synthesized and characterized by means of proton nuclear magnetic resonance (1H NMR) together with Fourier transform infrared spectroscopy (FT-IR). The nanocages were then introduced to natural rubber (NR) to afford organic-inorganic hybrid composites. Upon curing with dicumyl peroxide, the size of the dispersed phase was observed to decrease monotonically with increasing OV-POSS content, as depicted in scanning electron microscopy (SEM) images. This behavior differs significantly from that of analogous OV-POSS/NR vulcanizates cured with sulfur reported previously. To address this, the proportion of crosslinked OV-POSS was calculated using the results of FT-IR. The reaction enthalpy of the composites with different OV-POSS loading was recorded and analyzed by differential scanning calorimetry (DSC). A co-crosslinking reaction was suggested to play a crucial role in determining the morphologies of the composites. In addition, the agglomeration and crystallization of OV-POSS can also affect the morphologies of the composites.

Morphology and thermomechanical properties of natural rubber vulcanizates containing octavinyl polyhedral oligomeric silsesquioxane

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.

Using organic coatings helps to protect PET (polyethylene terephthalates) surfaces, improve surface hardness, scratch resistance, and solvent resistance, prolong the service life of PET film, and to expand their scope of applications. There were some disadvantages, including poor flexibility and impact resistance in high-hardness coatings; organic coatings should also be modified to improve the toughness. Herein, a UV (ultraviolet curing) curable high-hardness organic coating used in PET surface protection was prepared and modified with inorganic nanoparticles, such as OVPOSS (octavinyl-polyhedral oligomeric silsesquioxane). The effects of the categories of nanoparticles on the coating performance were studied. UV-Vis spectra (ultraviolet visible light spectra), FT-IR (Fourier transform infrared spectrometer), TGA (thermogravimetric analysis), DMA (dynamic-mechanical), SEM (field emission scanning electron microscope), and AFM (atomic force microscope) were used to characterize the properties of the coatings. The results showed that the addition of eight-vinyl POSS to the organic coating significantly increased its glass transition temperature (Tg) from 100 to 120 °C, improved its storage modulus from 167.6 to 258.9 MPa, and raised its impact resistance and flexibility. The SEM and AFM images displayed that the eight-vinyl POSS particles were dispersed homogeneously in the coating, arranged in an ordered network, and had good compatibility with organic components. The film displayed excellent properties, including 4 H of the pencil hardness, 100 g cm of impact resistance, excellent flexibility, and 90% of light transmittance, with the addition of 0.3 wt % OVPOSS. TGA analysis revealed that the coating had good thermal stability, with 5% weight loss temperature up to 335 °C.

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.

Hydrogels based on pH-sensitive polymers are of great interest as potential biomaterials for the controlled delivery of drug molecules. In this study, a novel pH-sensitive copolymer hydrogel based on acrylic acid (AA) monomer by free-radical solution polymerization were synthesized with organic–inorganic cross-linking agent of octavinyl polyhedral oligomeric silsesquioxane (OVPOSS). And its properties were compared with conventional hydrogels using N,N′-methylenebisacrylamide (MBA) as cross-linking agent. The copolymers were characterized by Fourier transform infrared spectra and differential scanning calorimetry. The morphology after swelling was presented by scanning electron microscopy. Swelling behaviors in different pH and potential applications in controlled drug delivery of the hydrogels were also examined. The results showed that both hydrogels were pH sensitive. However, as the addition of OVPOSS limited the movement of the molecular chain segment, the swelling ratio and the drug-release rate of theophylline in SGF decreased obviously when using OVPOSS as cross-linking agent, comparing with P(MBA-co-AA) hydrogels. The results in this study suggested that P(OVPOSS-co-AA) could serve as potential candidate for theophylline drug delivery.

Shape memory polymers are smart materials having the ability to change their shape under external stimulus. One of the most widely used shape memory polymers is cross-linked polyethylene (PE). The cross-linked polyethylene can be triggered by temperature to transfer from its permanent shape to programmed shape. Polyhedral oligomeric silsesquioxanes (POSSs) are the new generation of hybrid nanoparticles that positively affect the thermal stability, thermo-mechanical strength, flow properties and crystallization rates of the polymers. POSSs can also be used as crosslinking agents. Besides, coagents are used in order to improve the crosslinking efficiency by reducing undesirable side reactions such as chain breakage or disproportionation. They form bridges between polymer chains to be cross-linked. The aim of this study is to investigate the synergistic effects between POSS and coagent on the physical and shape memory properties of cross-linked linear low-density polyethylene (LLDPE). Octavinyl POSS (OvPOSS) nanoparticles and poly(ethylene glycol) dimethacrylate (PEGDMA) were used as coagents in this study. The peroxide used in crosslinking was di tert-butyl cumyl peroxide (PRX). Its content was kept constant as 1 phr. LLDPE/OvPOSS/PRX, LLDPE/PEGDMA/PRX and LLDPE/OvPOSS/PEGDMA/PRX composites were prepared in an Xplore model micro-compounder at a screw speed of 50 rpm and 135°C barrel temperature. The crosslinking was carried out using a hot-press operated at 175°C. The samples were characterized by performing differential scanning calorimetry (DSC), scanning electron microscopy (SEM), rheology, tensile tests and shape memory tests. Rheological analysis showed that the degree of crosslinking, storage modulus and complex viscosity increased in the presence of OvPOSS and PEGDMA. A synergistic effect was observed between OvPOSS and PEGDMA coagents.

Submicron/nano-structured icephobic surfaces made from fluorinated polymethylsiloxane and octavinyl-POSS

Preparation and properties of POSS grafted polypropylene by reactive blending

Stability of POSS crosslinks and aggregates in tetrafluoroethylene-propylene elastomers/OVPOSS composites exposed to hydrochloric acid solution

Surface functionalization of molybdenum disulfide (MoS2) was prepared by a simple reflux reaction between DITG-MoS2 and octa-vinyl polyhedral oligomeric silsesquioxanes (OvlPOSS). The structure of OvlPOSS-MoS2 was confirmed by XRD, FTIR and TEM. The SEM and TEM results of fracture surface exhibited that OvlPOSS-MoS2 was dispersed well in the matrix due to the good interfacial interaction between the functionalized MoS2 and PVA. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results indicated that the thermal decomposition temperature and the glass transition temperature (Tg) were improved. Compared with pure PVA, the maximum degradation temperature of the PVA/OvlPOSS-MoS2 nanocomposites was increased by 23 °C, and the Tg of the PVA/OvlPOSS-MoS2 was improved by 10.2 °C. Meanwhile, the peak of heat release rate (pHRR) and total heat release (THR) were decreased. The tensile stress was increased by 57% with addition of 2 wt% OvlPOSS-MoS2. Moreover, the addition of OvlPOSS-MoS2 significantly decreased the gaseous products, including hydrocarbons, carbonyl compounds and carbon monoxide, which was attributed to the synergistic effect of OvlPOSS and MoS2: the adsorption and barrier effect of MoS2 inhibited the heat and gas release and promoted the formation of graphitized carbons, while OvlPOSS improved the thermal oxidative resistance of the char layer.

ABSTRACTThree kinds of hybrids with different architectures including dumbbell‐type, bead‐type, and cross‐linked structure, were prepared via the Heck reaction between octavinyl‐polyhedral oligomeric silsesquioxane (OV‐POSS) and different bromo‐substituted aromatic amide monomers. The molecular architecture can be successfully achieved by simply varying the feed ratio of OV‐POSS to monomers. Their structure and properties were characterized by FTIR,1H NMR,29Si NMR, provide the expansion for FTIR and NMR] All the POSS‐based hybrids exhibited good thermal stability and low dielectric constant properties. The relationship between chemical structure, molecular architecture, and the dielectric constant of these hybrids were investigated in detail. The results show that POSS content dominated the low dielectric constant of the hybrids, while the chemical structure of organic chains and molecular architecture also play an important role on the formation of low dielectric constant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 42292.

Latex paint is a water‐based paint that uses synthetic polymers as a binder. It is widely used for outdoor environments. This has brought fungal growth due to the combination of moisture, organic matter, and environmental conditions. This study proposed a feasibility study on preparing antifungal latex binders based on natural rubber (NR) latex and acrylic emulsion (AE) blends. It started with latex film preparation before applying it as a latex binder. They were prepared with various levels of the antifungal agent, namely triclosan, in the blends. Results exhibited a very unique morphology when imaging through a scanning electron microscope (SEM). A flower‐like morphology was seen after adding triclosan to the latex films. The prepared films were further characterized in terms of thermomechanical responses to dynamic mechanical analysis (DMA) and temperature scanning stress relaxation (TSSR). In DMA, there were no significant changes in the glass transition temperatures ( T g ) of NR and AE. However, there were obvious changes in the magnitude of the loss tangent (tan δ) over the temperature ranges from −50 to −30 °C and from 70 to 100 °C, where the loss tangent fluctuated due to triclosan. Moreover, triclosan also influenced the antifungal activity of the samples in a dose‐dependent manner: the antifungal efficiency increased with the additional level of triclosan. Triclosan is classified as a phenolic antimicrobial agent. Even though triclosan is chemically non‐polar, its structure depends on the environment making it adapt to polarity. Therefore, triclosan may penetrate through the cell membrane and inhibit the growth of spores. The overall results supported the feasibility study on the preparation of antifungal latex binders with good mechanical performance. Highlights This study prepared latex compounds with good antifungal performance. A novel flower‐like morphology in natural rubber latex was surprisingly observed. Triclosan kills fungi by disrupting the cell wall and interfering with the lipid components. Triclosan provides various polarity conditions by rotating its ether bond. The polarity of Triclosan increased over the bond rotation from 30 to 90 °.

The core-shell nanocomposite particles were prepared from acrylate monomers and octavinyl polyhedral oligomeric silsesquioxane (V-POSS) by emulsion polymerization. The structure and properties of emulsion and latex film were characterized by FT-IR, dynamic mechanical analysis (DMA) and TEM and laser particle diameter analyzer (LPDA). The results showed that the V-POSS/polyacrylated (V-POSS/PMA) composite latexes was prepared and the diameter is about 36.1 nm when added 5wt% V-POSS. DMA results showed that the mechanical loss (tanδ) peak temperature (Tp) of the film enhance with increasing V-POSS content and had the best high Tp at 88.4°C for added 7 wt% V-POSS, which increased 7.8 °C than had not V-POSS. Thermogravimetric analysis (TGA) showed that the addition of V-POSS can increase the thermal decomposition temperature and improved the thermal stability of polyacrylate.

The phenomenon of stress relaxation in thermoplastic elastomers (TPEs) is common and influences the end‐use properties of polymers. Temperature scanning stress relaxation (TSSR) method extends an advanced method to study the stress relaxation of TPEs at elevated temperatures. A reactive blend system based on maleic anhydride grafted styrene‐ethylene‐butylene‐styrene and thermoplastic polyurethane is explored for its relaxation behavior at temperature up to 200°C with TSSR meter. The relaxation spectrum revealed the transitions occurring in the blends as well as the extent of interfacial interaction present. Direct measurement of elasticity of the blends was obtained from the TSSR index (RI). Glass transition temperature of the samples was measured from dynamic mechanical analysis. The elastic nature of the blends was also pursued from the storage modulus values and results were in line with TSSR results. The density of crosslinks in the system was assessed with both TSSR and the conventional Flory‐Rehner equation and a similar trend was obtained. Atomic force microscopy and scanning electron microscopy revealed the dispersed morphology of the blends.