Polyhedral Oligomeric Silsesquioxane Monomers Research Articles

Biosensor for ATP detection via aptamer-modified PDA@POSS nanoparticles synthesized in a microfluidic reactor

This study introduces aptamer-functionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticles for adenosine triphosphate (ATP) detection where the POSS nanoparticles were synthesized in a one-step, continuous flow microfluidic reactor utilizing thermal polymerization. A microemulsion containing POSS monomers was generated in the microfluidic reactor which was designed to prevent clogging by using a continuous oil flow around the emulsion during thermal polymerization. Surfaces of POSS nanoparticles were biomimetically modified by polydopamine. The aptamer sequence for ATP was successfully attached to POSS nanoparticles. The aptamer-modified POSS nanoparticles were tested for affinity-based biosensor applications using ATP as a model molecule. The nanoparticles were able to capture ATP molecules successfully with an affinity constant of 46.5 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu $$\\end{document}M. Based on this result, it was shown, for the first time, that microfluidic synthesis of POSS nanoparticles can be utilized in designing aptamer-functionalized nanosystems for biosensor applications. The integration of POSS in biosensing technologies not only exemplifies the versatility and efficacy of these nanoparticles but also marks a significant contribution to the field of biorecognition and sample preparation.

Polymers with double‐decker and side‐opened cage silsesquioxanes: Effects of cage structures on materials properties

AbstractCage silsesquioxanes, also known as polyhedral oligomeric silsesquioxanes (POSS), serve as crucial building blocks in crafting precisely designed organic–inorganic hybrid materials, given that their well‐defined silsesquioxane clusters can be adorned with organic substituents. While polymers with POSS in their main chains have been thoroughly examined, analyzing the correlation between cage structure and material properties in main‐chain‐type polymers remains challenging. This difficulty stems from the limited range of organic substituents on traditional POSS monomers, thereby precluding comparisons between polymers with unified substituents and different cage structures. In this study, we synthesized double‐decker silsesquioxane (DDSQ) and side‐opened POSS (SO‐POSS) monomers, both featuring phenyl groups. Subsequent platinum‐catalyzed hydrosilylation polymerization yielded main‐chain‐polymers. Both the cage and linker structures influence thermal stability and the glass transition temperature, while the hardness was primarily determined by the linker structure. This research is the first to elucidate the impact of cage structure on the material properties of main‐chain‐type POSS polymers.

Polymers and cyclic compounds based on a side‐opening type cage silsesquioxane

ABSTRACTPolymers having polyhedral oligomeric silsesquioxane (POSS) in the main chains are an important class of organic–inorganic hybrid materials. Despite the increasing attention to the POSS polymers, variation of the monomers is still limited. Herein, we have proposed side‐opening POSS (SO‐POSS) monomers. Platinum‐catalyzed hydrosilylation polymerization proceeded to produce polysiloxanes having SO‐POSS in the main chains. The obtained polysiloxanes showed good solubility, high thermal stability, high transparency, and tunable reflective index. In addition, cyclic compounds were obtained during the investigation of the polymerization, and were synthesized with high selectivity under the slightly diluted conditions. The obtained cyclic compounds showed high thermal stability due to the silsesquioxane backbone, and the high dispersibility as a filler in poly(methyl methacrylate) was demonstrated. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2243–2250

In-situ growth of Ag on mussel-inspired polydopamine@poly(M-POSS) hybrid nanoparticles and their catalytic activity

Polyhedral oligomeric silsesquioxane (POSS) nanoparticles have gain much attention due to their organic and inorganic hybrid structure that combine with metal nanoparticles to improve their functional properties for utilize in potential application areas. In this study, we first time present a green route for in-situ growth of silver on the surface of POSS based support particles by using mussel inspired polydopamine (PDA) coating. The POSS based nanocomposite support were synthesized by free radical mechanism in one-step emulsion polymerization of methacryl(M)-POSS monomer. Smooth spherical shape in size range of 200 nm–400 nm poly(M-POSS) hybrid latex particles were covered by the functional amine and catechol groups of PDA. Silver layer were growth on PDA@poly(M-POSS) nanocomposite template. The novel multi-functional Ag@PDA@poly(M-POSS) nanocomposite particles were fully characterized by SEM, EDAX, XRD and FTIR analysis. The catalytic activity of the particles was checked by pseudo-first order kinetic reaction of nitrophenol compound, which is highly toxic for environment. The catalytic reaction performance was discussed by varying the catalyst amount and concentration of 4-nitrophenol. Compare to similar catalysts, results showed that Ag@PDA@poly(M-POSS) nanocomposite particles exhibited excellent catalytic activity for the rapid degradation of 4-NP.

General Strategy for the Preparation of Stable Luminous Nanocomposite Inks Using Chemically Addressable CsPbX3 Peroskite Nanocrystals

The potential optoelectronic applications of perovskite nanocrystals (NCs) are primarily limited by major material instability arising from the ionic nature of the NC lattice. Herein, we introduce a facile and effective strategy to prepare extremely stable CsPbX3 NC–polymer composites. NC surfaces are passivated with reactive methacrylic acid (MA) ligands, resulting in the formation of homogeneous nanocubes (abbreviated as MA-NCs) with a size of 14–17 nm and a photoluminescence quantum yield above 80%. The free double bonds on the surface then serve as chemically addressable synthetic handles, enabling UV-induced radical polymerization. Critically, a bromide-rich environment is developed to prevent NC sintering. The composites obtained from copolymerizing MA-NCs with hydrophobic methyl methacrylate and methacrylisobutyl polyhedral oligomeric silsesquioxane monomers exhibit enhanced properties compared to previously reported encapsulated NCs, including higher quantum yields, remarkable chemical stability t...

Synergistic effect of liquid crystal and polyhedral oligomeric silsesquioxane to prepare molecularly imprinted polymer for paclitaxel delivery

A strategy based on the synergistic effect of polyhedral oligomeric silsesquioxane (POSS) and liquid crystal (LC) was described to prepare molecularly imprinted polymers (MIPs). A typical polymerization system was composed of 4-methyl phenyl dicyclohexyl ethylene (MPDE)(LC monomer), methacryllsobutyl POSS (POSS monomer), methacrylic acid, as well as ethylene glycol dimethacrylate (EDMA). The cooperative effect of LC and POSS was demonstrated by comparing the adsoption amount and imprinting factor of the LC POSS MIPs with that of other MIPs prepared using only LC or POSS monomer, as well as MIP made without LC and POSS. The influence of the content of POSS, the ratio of the template to functional monomer as well as the types of LC monomer on imprinting performance was investigated. A detailed morphology study of the MIPs displayed that the simultaneous use of LC and POSS monomer to prepare MIPs also produced the changes in pore structure different from the use of LC or POSS monomer independently. The reinforced imprinted effect of LC POSS MIPs against paclitaxel (PTX) was also approved by superior controlled release characteristics through analyzing the PTX release kinetics. The cytotoxicity of each polymer was lower than the drug-loaded polymer, which was measured by using the MTT assay with human breast cancer cell (MCF-7 cell). Compared with pure PTX, LC POSS MIPs displayed a higher relative bioavailability of 242.5%, while the LC POSS-free control MIPs and POSS LC-free control MIPs only 127.4 and 63.2%, respectively.

Tunable Porosity of Cross-Linked-Polyhedral Oligomeric Silsesquioxane Supports for Palladium-Catalyzed Aerobic Alcohol Oxidation in Water.

Polyhedral oligomeric silsesquioxane (POSS)-based materials, poly-POSS-Tn [n = 8 (1), 10 (2), 12 (3), and mix (4)], were prepared in high yields via free radical polymerization of corresponding pure forms of methacrylate-functionalized POSS monomers, MMA-POSS-Tn (n = 8, 10, 12), and the mixture form, MMA-POSS-Tmix. Powder X-ray diffraction (XRD) spectra and BET analysis indicate that 1-4 are amorphous materials with high surface areas (683-839 m2 g-1). The surface areas and total pore volumes follow the trend: poly-POSS-T12 > poly-POSS-T10 > poly-POSS-Tmix > poly-POSS-T8. In addition, on the basis of Barrett-Joyner-Halenda (BJH) analysis, poly-POSS-T12 contains the highest amount of mesopores. The Pd nanoparticles immobilized on poly-POSS-Tn [n = 8 (5), 10 (6), 12 (7), and mix (8)] are well dispersed with 4-6 wt % Pd content and similar average particle sizes of 6.2-6.5 nm, according to transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDX) and microwave plasma-atomic emission spectroscopy (MP-AES). At 90 °C, the stabilized Pd nanoparticles in 5-8 catalyzed aerobic oxidation of benzyl alcohol to benzaldehyde in 72-100% yields at 6 h using a mixture of a H2O/Pluronic (P123) solution. The PdNp@poly-POSS-T8 catalyst (5) exhibited the lowest catalytic activity, as a result of its lowest surface areas, total pore volumes, and amounts of mesopores. With the catalyst 8, various benzyl alcohol derivatives were converted to the corresponding aldehydes in good to excellent yields. However, with alcoholic substrates featuring electron-withdrawing substituents, high conversions were achieved with 1 equiv of K2CO3 additive and longer reaction times.

Fluorinated and Thermo-Cross-Linked Polyhedral Oligomeric Silsesquioxanes: New Organic-Inorganic Hybrid Materials for High-Performance Dielectric Application.

A fluorinated and thermo-cross-linked polyhedral oligomeric silsesquioxane (POSS) has been successfully synthesized by thermal polymerization of a fluorinated POSS monomer having an inorganic silsesquioxane core and organic side chains bearing thermo-cross-linkable trifluorovinyl ether groups. This new inorganic-organic hybrid polymer shows high thermostability with a 5 wt % loss temperature of 436 °C, as well as good transparency (a sheet with an average thickness of 1.5 mm shows high transmittance of 92% varying from 400 to 1100 nm). Moreover, the polymer exhibits both low dielectric constant (<2.56) and low dissipation factor (<3.1 × 10-3) in a wide range of frequencies from 40 Hz to 30 MHz even at a high frequency of 5 GHz. The polymer also shows low water uptake (<0.04%) and low Dk (near 2.63) after immersing it in water at room temperature for 3 days. These data imply that this polymer is very suitable to be utilized as a high-performance dielectric material for fabrication of high-frequency printed circuit boards or encapsulation resins for integrated circuit dies in the microelectronic industry. Furthermore, this work also provides a route for the preparation of fluorinated POSS-based polymers.

Molecularly imprinted polymer prepared with polyhedral oligomeric silsesquioxane through reversible addition-fragmentation chain transfer polymerization.

Polyhedral oligomeric silsesquioxane (POSS) was utilized to prepare imprinted polymer through reversible addition-fragmentation chain transfer polymerization (RAFT) successfully. The imprinted polymer was made with a mixture of RAFT agent, 4-vinylpyridine (4-VP), POSS monomer [PSS-(1-propylmethacrylate)-heptaisobutyl substituted, MA 0702], and ethylene glycol dimethacrylate (EDMA), with ketoprofen (KET) as template. The influence of polymerization variables, the amount of RAFT agent and POSS monomer, the ratio of KET to 4-VP, and the ratio of 4-VP to EDMA, were investigated on the retention factor and imprinting effect. The greatest imprinting factor of the RAFT agent-based POSS MIP was 15.2, about 1.5 times higher than the RAFT agent-free agent POSS MIP. The permeability, surface morphology, as well as pore size distribution of POSS MIP monoliths made with RAFT agent and without RAFT agent were also studied. The optimal MIP was applied to solid phase extraction for KET from commercial tablets. The mean recoveries of KET for RAFT-based POSS MIP was 85.2% with a relative standard deviation of 2.6%.

Preparation and characterization of polyurethane/POSS hybrid aqueous dispersions from mono-amino substituted POSS

A series of linear polyurethane (PU) aqueous dispersions modified by polyhedral oligomeric silsesquioxane (POSS) was synthesized by incorporating various amounts (ca. 2–10 wt%) of a secondary amino-terminated monofunctional POSS in hexamethylene diisocyanate trimer (HDI-T), hexamethylene diisocyanate, poly(tetramethylene-oxide) and 2,2-bis(hydroxymethyl)propionic acid. Results from the gel permeation chromatography, Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction showed that the POSS monomers could be effectively introduced into the PU matrices based on HDI-T to obtain stable aqueous and homogenous PU/POSS hybrid dispersions. The thermal properties of the hybrids do not significantly affect the degradation mechanism of the PU. The physical properties of the PU/POSS hybrid films changed, with a notable increase in tensile strength and surface hydrophobicity.

Advanced Aromatic Polymers with Excellent Antiatomic Oxygen Performance Derived from Molecular Precursor Strategy and Copolymerization of Polyhedral Oligomeric Silsesquioxane.

In this contribution, the advanced aromatic polymers with excellent antiatomic oxygen (AO) performance were designed and synthesized using molecular precursor strategy and copolymerization of polyhedral oligomeric silsesquioxane (POSS). A soluble poly(p-phenylene benzobisoxazole) (PBO) precursor, that is, TBS-PBO (tert-butyldimethylsilyl was denoted as TBS), was designed to overcome the poor solubility of PBO in organic solvents. Then the new copolymer of TBS-PBO-POSS was synthesized by the copolymerization of TBS-PBO and POSS, which possessed good solubility and film-forming ability in common organic solvents, such as N-methylpyrrolidone, N,N-dimethylacetamide, and dimethyl sulfoxide. More importantly, the TBS-PBO-POSS films exhibited outstanding antiatomic oxygen properties because of the incorporation of POSS monomers with cagelike structure into the main chain of copolymer, which drastically reduced the AO-induced erosion owing to the formation of the passivating silica layer on the surface of polymers. When the TBS-PBO-POSS films were exposed to AO effective fluences of 1.5495×10(20) atom cm(-2) (5 h) and 4.6486×10(20) atom cm(-2) (15 h), the relative mass loss was merely 0.19% and 0.41%, respectively. This work provides a new perspective and efficient strategy for the molecular design of aromatic heterocyclic polymers possessing excellent combination properties including processing convenience and antioxidative and mechanical properties, which can be employed as potential candidates to endure the aggressive environment encountered in low earth orbits.

ATRP of POSS Monomers Revisited: Toward High-Molecular Weight Methacrylate–POSS (Co)Polymers

For the first time, ATRP was successfully employed for homopolymerization of a commercial methacrylate-functionalized polyhedral oligomeric silsesquioxane (POSS) monomer, iBuPOSSMA, to high molecular weights. It was found that iBuPOSSMA has a low ceiling temperature (Tc); therefore, low temperatures and/or high initial monomer concentrations need to be used in order to avoid low degrees of polymerization that had been observed previously. The values of Tc, as well as of the polymerization enthalpy ΔHp and entropy ΔSp were determined to be 130 °C (at [M]0 = 1 M), −41 kJ mol–1, and −101 J mol–1 K–1, respectively. Under optimized conditions, poly(iBuPOSSMA) homopolymers having low dispersity and high Mn, ranging from 23 000 to 460 000, were obtained in a well-controlled ATRP process. Moreover, various block copolymers having high-Mn poly(iBuPOSSMA) blocks were prepared by copolymerization of iBuPOSSMA with methyl methacrylate and styrene.

Structure ordering and reinforcement in POSS containing hybrids

The rubbery Epoxy–POSS (polyhedral oligomeric silsesquioxane) hybrid networks have been prepared by incorporating the novel diepoxy–POSS monomer in an epoxy network. During the hybrid network formation, monitored in situ by SAXS, the POSS units self-assemble to form crystalline lamellae in the epoxy matrix. The ordered organic–inorganic hybrid shows the temperature induced order–order and order–disorder transitions due to breaking the POSS domains. The proposed structural model of the hybrid involves the ordered POSS lamellae and cylinders as well as the disordered arrangement of POSS units. Dynamics of the self-assembly processes was investigated by DMA measured at different frequencies of shear deformation. The well-arranged POSS domains provide the hybrid with a significant reinforcement. Moreover, the hybrid with a high POSS content undergoes a strain induced stiffening due to rearrangement of the ordered structure. The effect of POSS–POSS interactions on the hybrid ordering and reinforcement is discussed.

Formation of a crosslinked POSS network by an unusual hydrosilylation: Thermo-oxidative stabilization of the α-cristobalite phase in its amorphous regions

A semicrystalline inorganic–organic hybrid crosslinked network containing polyhedral oligomeric silsesquioxane (POSS) cores was constructed by the unusual hydrosilylation of the terminal vinyl groups of an internal acetylene-containing silane linker by a POSS monomer. Products from the thermal treatments of this network in either argon or air at 250, 550, and 1000 °C, respectively, were characterized by Fourier transform infrared, Solid-state 13C and 29Si magic angle spinning NMR, X-ray diffraction and XPS analyses. The highly symmetrically functionalized POSS silica clusters, in the fluorite silica phase, in the network were found to remain unchanged on thermal treatment possibly due to the shielding of the silica core by the functionalities and a cancellation of thermal stresses on the silica core. Stabilization of the metastable α-cristobalite phase, which is typically formed on cooling by a β- to α-transition of the β-cristobalite phase formed above 1400 °C, was observed in the amorphous regions in the network sample treated only to 1000 °C in air. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Atomic Oxygen Effects on POSS Polyimides in Low Earth Orbit

Kapton polyimde is extensively used in solar arrays, spacecraft thermal blankets, and space inflatable structures. Upon exposure to atomic oxygen in low Earth orbit (LEO), Kapton is severely eroded. An effective approach to prevent this erosion is to incorporate polyhedral oligomeric silsesquioxane (POSS) into the polyimide matrix by copolymerizing POSS monomers with the polyimide precursor. The copolymerization of POSS provides Si and O in the polymer matrix on the nano level. During exposure of POSS polyimide to atomic oxygen, organic material is degraded, and a silica passivation layer is formed. This silica layer protects the underlying polymer from further degradation. Laboratory and space-flight experiments have shown that POSS polyimides are highly resistant to atomic-oxygen attack, with erosion yields that may be as little as 1% those of Kapton. The results of all the studies indicate that POSS polyimide would be a space-survivable replacement for Kapton on spacecraft that operate in the LEO environment.

ESI and MALDI mass spectrometry of large POSS oligomers

A series of Polyhedral Oligomeric Silsesquioxane (POSS) propylmethacrylate (PMA) and styryl oligomers were prepared from POSS monomers, R 7R'Si 8O 12, containing 1 functional R’ group for polymerization and 7 inert R-groups where R = isobutyl (i-butyl), phenyl (Ph), cyclohexyl (Cy) or cyclopentyl (Cp). Both standard atom transfer radical polymerization (ATRP) and free radical syntheses, the latter employing azoisobutylnitrile as the free radical initiator were used in the syntheses. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectra were obtained in a new matrix, 4,4′-dihydroxyoctafluoroazobenzene which was especially designed for insoluble and intractable polymeric materials. Well-resolved series of oligomers were observed out to n = ∼13 in both the linear and reflectron modes. Major peaks were assigned based on tandem mass spectrometry (MSMS) fragmentation patterns to give a consistent explanation of the observed spectra. In all cases, ionization of the ATRP products gave cationized parent ions in which the terminal Br atom was replaced by hydrogen. Additional observed peaks were due to loss of POSS side chains from the oligomer backbone. The free radical products were terminated with either one or two isobutylnitrile groups. Electrospray ionization (ESI) spectra were more complex than the MALDI-TOF but showed either identical parent ions or closely related hydroxylated parent ions.

Preparation and properties of ethylene/POSS copolymer with rac‐Et(Ind)2ZrCl2 catalyst

AbstractThe various monovinyl‐functional polyhedral oligomeric silsesquioxane (POSS) monomers had been copolymerized with ethylene (E) using rac‐Et(Ind)2ZrCl2 and a modified methylaluminoxane (MMAO) cocatalyst. The unreacted POSS monomer could be removed completely by washing the copolymerization product with n‐hexane. And the copolymers were characterized with 1H NMR, TEM, DSC, TGA, and GPC to know the composition, thermal properties, molecular weight and its distribution, respectively. According to 1H NMR data, the monomer reactivity ratios of various POSS monomers were calculated by the Fineman‐Ross and Kelen‐Tudos methods. Thermogravimetric analysis of E/POSS copolymers exhibited an improved thermal stability with a higher degradation temperature and char yields, demonstrating that the inclusion of inorganic POSS nanoparticles made the organic polymer matrix more thermally robust. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Epoxy silsesquioxane resists for UV nanoimprint lithography

Photopolymerizable epoxy polyhedral oligomeric silsesquioxane monomers with variable aliphatic spacer have been prepared and cured under UV radiation. Due to their organic/inorganic composition, these materials are promising candidates for microelectronic applications which requires high thermal and mechanical stabilities as well as a low dielectric constant, for example, for the fabrication of electrical interconnects. The authors pointed out by ellipsometric measurements that the use of a sensitizer in addition to the photoinitiator enhances the kinetic of the cationic polymerization of epoxy groups. The polymerization performed either in an EVG770® nanoimprint lithography stepper or under normal atmospheric conditions has been investigated by infrared spectroscopy, delivering information concerning polymerization mechanisms and allowing the optimization of the resin composition. Thermogravimetric analyses have shown that an annealing step is necessary after the UV curing of the resin to eliminate inert residues of the photoinitiator dissociation and thus improving the thermal resistance of the polymer. Finally they have demonstrated that the obtained polymers form interpenetrated networks and that their mechanical properties are retained up to a temperature of 375°C.

Synthesis and Luminescent Property of Polycarbazole/Polyhedral Oligomeric Silsesquioxane Nanocomposites

Polyvinylcarbazole(PVK) composites containing organic-inorganic hybrid polyhedral oligomeric silsesquioxane(POSS) PVK-POSS were prepared by free radical polymerization. POSS monomers reacted with vinylcarbazole and were completely dispersed at molecular level in PVK matrix and PVK-POSS nanocomposites display higher glass transition temperature(Tg) in comparison with neat PVK. Optical properties of PVK/POSS nanocomposites were investigated by UV-spectrum and PL-spectrum and the results show that the PVK-POSS nanoparticles have a good interface effect and improve color purity effectively. The maximum absorption wavelength bathochromically shifts gradually with the increasing of the content of POSS. The luminescent intensity becomes higher and higher with the increase of POSS content, and reaches its maximum luminescent intensity when the POSS content is 3% (mass fraction), while some POSS-rich nanoparticles are present in matrix when contents of POSS are beyond 5%.

Aggregation of POSS Monomers in Liquid Hexane: A Molecular-Simulation Study

Polyhedral oligomeric silsesquioxanes (POSS) are multifunctional molecules that can be employed as building blocks to develop nanocomposite materials whose mechanical properties often improve upon those of traditional polymeric materials. We report here molecular simulation results for the effective potential of mean force between octamethyl POSS monomers and between POSS monomers in which one methyl group has been substituted by a linear alkane chain of nine carbon atoms in liquid normal hexane at 300 and 400 K. The results are discussed and compared to available data for the effective interactions between octamethyl POSS monomers in normal hexadecane. Our results show that the effective short-ranged POSS-POSS attraction is significantly weaker in hexane than it is in hexadecane, perhaps explaining why normal hexane is often the solvent of choice for the preparation of POSS-containing materials. Additionally, we provide results for the radial distribution functions between selected sites in the POSS monomers that can be used both to understand the association between POSS monomers in solution and to parametrize coarse-grained simulation models. Such models will be used to study the formation of POSS-containing supramolecular structures such as lamellae or micelles that are currently not accessible by atomistic simulation and can be compared to experimental observations.