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Intrinsic healable polymers are materials capable of repairing itself through its chemical nature, in order to improve stability and durability and to restore the lost functionalities or properties. In this study, azobenzene (AZO)moieties were incorporated into a previously reported bridged silsesquioxane based on the reaction of isocyanatepropyltriethoxysilane (IPTS)with bisphenol A (BPA), by replacing a small fraction of BPA by a bisazophenol (4,4′-dihydroxyazobenzene, AZOH). The incorporation of these AZO moieties led to a material with UV light-induced healing abilities. The underlying healing mechanism is attributed to the intra-molecular conformational changes of the azo-chromophores that are induced by the trans to cis photoisomerization of the azobenzene. These changes temporary increased its mobility and allowed the material to flow in the damaged area, followed by a process of restoring the physical hydrogen bonds. This process was monitored following the viscoelastic properties during successive cycles of turning ON and OFF the UV irradiation. Remarkably, the resultant healed material has not significant observed mechanical differences with the original one. Fil: Galante, Maria Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Zucchi, Ileana Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Oyanguren, Patricia Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina Fil: Sáiz, Luciana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Although epoxy resins have been widely used for engineering applications because of their excellent mechanical properties, they can be brittle and vulnerable to fracture. Such brittle behavior becomes more severe when such resins are subjected to extremely low-temperature environments. In this study, we employ polyhedral oligomeric silsesquioxane (POSS) reinforcement to improve the mechanical properties under cryogenic conditions (77 K). Nanocomposites are prepared by adding POSS at 0.5–8 wt.% to an amine-cured DGEBF based epoxy resin. The results show that at 77 K the fracture toughness of the neat resin increases compared to room temperature due to the increase in intermolecular forces. The fracture toughness results also showed that the addition of POSS leads to an additional 40% improvement in fracture toughness at 77 K at 5 wt.% of POSS loading, as compared to neat resin. Positron annihilation lifetime spectroscopy indicate no changes in the free volume inside the molecular network with the inclusion of POSS. Addition of POSS leads to the formation of compliant domains, as shown by transmission electron microscopy. Scanning electron microscopy of fractured surfaces shows evidence of extrinsic toughening mechanisms due to POSS inclusion. T g variation corroborates the existence of soft POSS-POSS domains.

Recovery rate and recovery stress are important factors that limit the use of polyurethanes, especially in the medical field. In this study, Polyhedral Oligomeric Silsesquioxane nanoparticles as chain extender have been bonded to polyurethane chains using a new synthesis method. Fourier-transform infrared spectroscopy technique to confirm synthesis reactions, Differential Scanning Calorimetry for evaluating the effect of Polyhedral Oligomeric Silsesquioxane (POSS) particles on the crystallinity of soft segments, Dynamic Mechanical Thermal Analysis for investigating mechanical properties, and Scanning Electron Microscope and X-ray diffraction have been used to evaluate the dispersion of Nanoparticles, respectively. It is observed that using Polyhedral Oligomeric Silsesquioxane solely, acts as a chain extender which does not show phase separation in synthesized nanocomposites. Using both the Polyhedral Oligomeric Silsesquioxane and 1,4-Butanediol chain extender in polyurethane synthesis reaction caused greater phase separation rather than solely 1,4-Butanediol. Finally, adding the nanoparticles caused improvement in recovery rate as well as shape recovery in the synthesized nanocomposites.

In this study, a facile synthetic approach was demonstrated for the preparation of graphene oxide (GO)-modified soluble polyimide (SPI) nanocomposites with enhanced mechanical properties. Firstly, a two-step method was employed to form SPI via polymerization of cycloaliphatic dianhydride (bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride) and aromatic diamine (2,2′-Bis[4-(4-aminophenoxy)phenyl]propane). Amino-substituted silsesquioxane (SQ) was used to conjugate with GO to form SQ-grafted graphene oxide (SQ@GO) and thermally-treated SQ@GO (TSQ@GO). Fourier-transformed infrared spectroscopy, 29Si nuclear magnetic resonance spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrometry were used complementarily for the study of the chemical structures of the prepared SQ@GO, TSQ@GO and SPI/TSQ@GO nanocomposite film (i.e., TSQ@GO in SPI matrix). Results show successful synthesis of SQ@GO, TSQ@GO and SPI/TSQ@GO nanocomposite film. With support of excellent dispersibility of TSQ@GO in SPI matrix, the tensile properties of SPI improved significantly via hybridization with TSQ@GO: tensile strength enhanced to 1.3X and elongation at break increased to 3 folds. This study demonstrated a prototype method for fabrication of pre-imidized SPI/TSQ@GO nanocomposite, which has shown the promise for moderate-temperature manufacture (below 200 °C) of emerging electronic applications.

Polydimethylsiloxane (PDMS) elastomers are widely used in many applications, such as in microfluidic devices or as membranes. These slightly cross-linked PDMS networks suffer from severe swelling upon contact with, especially non-polar, organic solvents, thereby drastically reducing the performance of the device. Here, we report on a new method to prepare ultra-thin, highly cross-linked PDMS films in a localized fashion by the interfacial polymerization of PDMS with polyhedral oligomeric silsesquioxane (POSS). The resulting thin poly(PDMS-POSSimide) films (150 nm) showed to have a drastic reduction in swelling upon contact with n-hexane vapor (15-fold decrease) and ethyl acetate vapor (5-fold decrease). These poly(PDMS-POSSimide) films showed an increase in swelling upon contact with ethanol vapor (up to a 4-fold increase) as compared to conventional PDMS. We attribute this increase in swelling to the enhanced affinity for polar solvents of these poly(PDMS-POSSimide) films due to the presence of positively charged ammonium groups. Despite the highest swelling in ethanol, the poly(PDMS-POSSimide) films are found to have extremely low ethanol permeances (

Dual electrochromic and electrofluorochromic polymers have attracted immense attention due to their extensive applications in the fields of sensors, displays and advanced devices. We report here the electrochemical synthesis of a crosslinked polymer bearing tetraaniline, carbazole, and polyhedral oligomeric silsesquioxane through the hydrolysis reaction with good film-forming ability and outstanding thermostability. The resulting polymer with huge rigid polyhedral oligomeric silsesquioxane groups presents simultaneous electrochromic and electrofluorochromic behaviors with improved switching rate, caused by the enhanced ion diffusion. Furthermore, the contrast of on/off in the electrofluorochromism is also enhanced drastically, ascribed to the mitigation of the aggregation-caused quenching effect of fluorescence stemmed from the steric hindrance effect of polyhedral oligomeric silsesquioxane.

We report a series of PI composite fibers containing polyhedral oligomeric silsesquioxane (POSS). These fibers were fabricated by a three-step process consisting of the in situ polycondensation of POSS and polyamic acid, wet spinning, and thermal imidization. X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy proved that POSS enriched the surface of POSS/PI composite fibers during wet spinning. This surface enrichment enhanced the resistance to atomic oxygen (AO) erosion. After exposing the POSS/PI composite fibers to AO fluence up to 2.93 × 1020 atoms cm−2, the fibers still displayed excellent AO resistance. With increased POSS content from 0 wt% to 20 wt%, the retention of fracture strength and initial modulus considerably improved from 54% to 93% and from 64% to 91%, respectively. Moreover, the decay rates of fracture strength of the composite fibers obviously decreased at the same AO fluence with increased POSS content from 0 wt% to 20 wt%. AO erosion at a larger fluence further resulted in more effective AO resistance for composite fibers with higher POSS content. XPS results suggested as well that silicate passivated layers formed on the fiber surfaces after AO exposure, and these layers prevented the fibers from further AO erosion.

Benzoxazinyl modified polyhedral oligomeric silsesquioxane (BZPOSS) is successfully synthesized and used to prepare nanocomposites with bisphenol A cyanate ester (BADCy). The DSC results showed that the curing peak temperature of BZPOSS/BADCy blend decrease significantly from 317.1 °C to 160.3 °C, suggesting the high catalytic activity of BZPOSS to the polymerization of cyanate ester. The SEM micrographs of poly(BZPOSS/BADCy) and Silicon element distribution maps given by EDS both indicated that BZPOSS disperses evenly in BADCy. Dielectric properties tests showed that the dielectric constant can be reduced by the introduction of BZPOSS, which is attributed to the nano-pores from the cage structure of POSS. When 15 wt% BZPOSS was added, the dielectric constant decreased to 2.01 and the dielectric loss was also only 0.0070 at 1 MHz. Meanwhile, DMA and TGA result showed that the thermal stability and heat resistance of poly(BZPOSS/BADCy) at high temperature decreased with increasing BZPOSS, which is due to the change of crosslinking structure of the copolymers. The influences of the crosslinking structure and the nano-porous organic-inorganic hybrid particles on the dielectric and thermal property of poly(BZPOSS/BADCy) were also discussed.

A series of uncrosslinked and unentangled hybrid copolymers of N-isopropyl acrylamide (NIPAm) and polyhedral oligomeric silsesquioxane (POSS) exhibited dual, thermoplastic and hydrogel behavior. The products of the synthesis were characterized by nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The dried hybrids were amorphous and exhibited a reduction of glass transition temperature Tg as POSS content increased, i.e., ΔTg = Tg − Tg,bulk

The copolymers of ethylene with the double-decker silsesquioxane (DDSQ) were synthesized by copolymerization with the use of metallocene and bis(phenoxy-imine) catalysts. The influence of the kind of the catalyst and polyreaction conditions on the performance of copolymerization as well as on the properties of the copolymers was studied. Depending on polyreaction parameters, the DDSQ contents in the copolymer varied in the range of 0.93–11.53 wt% which determined the compositions and the structural properties of copolymers. DDSQ incorporated into the polymer chain could constitute pendant groups in the main chain or it could act as a cross-linking agent. The ethylene/DDSQ copolymers also had different kinds and contents of unsaturated end groups and they offered interesting morphological and thermal properties including various glass transition temperatures as well as melting and crystallization behaviours.

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.

A series of N-POSS-substituted polybenzimidazole (POSS-g-PBI) bearing polyhedral oligomeric silsesquioxane (POSS) pendant moieties were synthesized. X-ray powder diffraction analyses and Scanning electron microscope characterization revealed that POSS was dispersed well in the polybenzimidazole matrix. The grafted POSS pendant moieties can break the PBI intermolecular face-to-face packing and hydrogen bonding. As a result, POSS-g-PBIs showed better solubility than the pure polybenzimidazole because of less tight molecular chain packings. The intrinsic viscosity of POSS-g-PBI in a DMSO solution decreased with increasing amounts of grafted POSS in the polybenzimidazole molecular chains. The mechanical properties, including Young’s modulus, breaking strength and elongation at break, increased by introducing POSS into the polybenzimidazole backbone. Contact angle tests showed that the surface of POSS-g-PBI became hydrophobic with increasing amounts of grafted POSS. POSS-g-PBIs also exhibited good thermal stability.

The hybrid ethylene/POSS copolymers were obtained using the rac -Et(Ind) 2 ZrCl 2 catalyst activated by MAO. A series of monoalkenyl- and monoalkenyl(siloxy)silsesquioxanes derivatives with different structures of reactive alkenyl substituent and types of non-reactive groups attached to the T 8 POSS cage was used as comonomers. The kind and concentration of the POSS comonomer in the reaction feed as well as extended reaction time were found to strongly influence the catalyst efficiency and incorporation of POSS units into polymer chains. The comonomer reactivity was significantly dependent on the length of the alkenyl reactive substituent in the POSS molecule and it was highest for the POSS structures with medium-length of the alkenyl substituent due to their steric and inductive effects of the silicon-oxygen cage. The molecular weight as well as the kind and the content of unsaturated end groups in copolymers were dependent on the kind and amount of POSS comonomer in the reaction feed. The change in melting temperature, crystallinity degree, crystallization temperature and morphology of copolymers was observed as compared to neat polyethylene (PE).

Thermal degradation of oligomeric ladder-like vinyl- and phenylsilsesquioxanes can proceed at relatively low temperatures via evaporation of the shortest oligomers, accompanied by partial redistribution of side groups. The results of thermogravimetric (TGA) and differential thermogravimetric analysis (DTG) as well as differential scanning calorimetry (DSC) of the thermal decomposition process were combined with studies on the structure of the formed volatiles using Fourier transform infrared spectroscopy (FTIR) and gas chromatography coupled with mass spectrometry (GC–MS), as well as FTIR examination of the solid residues. The investigations have shown that the evaporation of oligomers is the main but not the only reason for the matrix decay. It can be accompanied by partial crosslinking of organic substituents even at relatively low temperatures. The latter process becomes more significant on both prolonged exposure to the mild heating or at temperatures higher than those characteristic for evaporation of oligomers.

Inclusion of self-healing and water-repellant properties within a commercially available elastomer could be of great significance in prolonging its longevity and sustainability. Herein, Diels-Alder (DA) ‘click’ reaction was employed to introduce self-healing and ultrahydrophobic features in commercially available ENR. In this case, the furfuryl groups were grafted onto the backbone of the pristine elastomer, followed by their DA ‘click’ modification with polyhedral oligomeric silsesquioxane isobutyl maleimide (POSSMI) molecules. Besides the provision of dynamic covalent linkages, the DA modified elastomer showed significantly improved hydrophobicity [water contact angle (WCA) > 140°], because of the presence of nano-sized POSS materials on the surface. In contrast to pristine ENR, the DA adduct POSS hybrid elastomer showed remarkably improved thermal stability, surface hardness, and adhesion to metal substrates. On heating at 120 °C, the furan-maleimide DA covalent linkages cleaved, which re-installed on annealing at 60 °C. In consequence, the DA elastomers exhibited relatively higher mechanical and healing efficacy than the pristine ENR.

Polyhedral oligomeric silsesquioxane (POSS) is non-toxic and tasteless, and has good biocompatibility, stability and other characteristics, which is used as a “nano-building” unit for the preparation of new organic–inorganic hybrid materials. POSS nanoparticles can be introduced into hydrogels via simple and easy methods such as physical blending, ionic interaction and covalent bonding to prepare POSS hybrid hydrogels with the rigidity of inorganic materials and the processability of organic materials. These excellent POSS hybrid hydrogels can be used in cell culture, bone regeneration, drug delivery and catalytic carriers. This brief review summarized the preparation methods of POSS hybrid hydrogels and related application research, and discussed some future applications of the hybrid hydrogels.

The configuration and amphipathicity of polymer templates are crucial in fabrication of hybrid microspheres via the self-assembling process. Here, a new star-like silsesquioxane-cored miktoarm copolymer (M−T8−P) with desired amphiphilicity was synthesized and sufficiently characterized by various methods. The hybrid amphipathic architectures endowed M−T8−P an attractive capability of stable encapsulation for oxidation-reponsive polysulfides (PSL) synthesized from sulfur and monoterpenes, and facilitated the formation of stable M−T8−P/PSL complex micelles, which further templated the construction of oxidation-active silica microspheres with micrometer dimensions through a simple one-pot sol–gel route. With the increasing of PSL/M−T8−P feed ratio, the size of microspheres and the content of PSL in the resulting microsphere were increased due to PSL droplets providing a soft-template for silica particles to build larger-sized silica microspheres with PSL cores, but the regularity of microspheres was decreased. The increased content of PSL and oxidation treatment could significantly enhanced adsorption capacity of hybrid microsphere for palladium (Ⅱ). On the basis of these promising results, the hybrid copolymer and microspheres might find the applications in water treatment and environmental protection.

Anthracycline conjugates, covalently bonded to the inorganic cage of polyhedral oligomeric silsesquioxanes, were successfully synthesized by reacting the primary amino group of daunorubicin and octakis-[3-(2-succinic anhydride)propyl,dimethylsiloxy]octasilsesquioxane (POSSAn) with a molar ratio 8:1, 3:1, and 1:1. The synthetic pathway involved hydrosilylation of octakis-(hydridodimethyl-siloxy)octasilsesquioxane (H-POSS) with allyl succinic anhydride, in the presence of Karstedt’s catalyst. POSS-DAU nanoparticles were used as the carriers for the anticancer drug daunorubicin (DAU), due to their high drug loading properties and comparatively low side effects. The coupling reaction proceeds quantitatively and leads to a highly soluble conjugate. The kinetics of the reaction was studied using FTIR spectroscopy, by observing changes to relevant peaks. The amount of DAU grafted in the POSS-DAU nanoparticles varied from 27 wt% to 66 wt%. The products were characterized using 1H, 13C, 29Si NMR, FTIR spectroscopy, SEM, and MALDI-Toff analysis. Mass spectrometry with electrospray ionization techniques (ESI) in the negative ion mode was successfully used for recording the mass spectra of the POSS-DAU nanoparticles. The hydrodynamic diameter and zeta potential of the POSS-DAU nanoparticles were determined by the DLS method.

The series of titanasilsesquioxanes that differ in a way of binding to the transition metal ( via one, two or three oxygen atoms) and type of nonreactive substituents bonded to inorganic oxygen-silicon cage ( i -Bu, Ph, c -C 6 H 11 ) were prepared by reacting of TiCl 4 with 1 eqv. of the silsesquioxane ligand. Upon treatment with an appropriate cocatalyst, all titanium precatalysts are active in ethylene and 1-octene polymerization and produce from low to high molecular weight polyethylenes and moderately ([ mmmm ] = 44–74%) isotactic poly(1-octene)s. The influence of polymerization parameters, type of cocatalyst and the silsesquioxane structure on the catalytic behavior of the title titanium silsesquioxane complexes have been investigated.

Due to its unique nanocage-like architecture and properties, polyhedral oligomeric silsesquioxane (POSS) has received tremendous attention from researchers in areas ranging from material science and engineering to biomedical fields. This has created opportunities for the applications of POSS in non-traditional areas such as nanomedicines, Li-ion batteries, and many more. Thanks to the recent advances in polymer chemistry, the POSS molecules have been successfully incorporated into well-defined organic polymeric structures leading to the creation of a plethora of well-defined hybrid nano architectures with novel properties and applications. POSS nanocage is typically a strongly hydrophobic entity, and since recently, its integration into amphiphilic macromolecular design has been a fascinating area of research activity with many interesting studies ranging from academic research to practical applications. This article encompasses new ideas and research work carried out over the last several years in this relatively new area of water soluble/amphiphilic hybrids with a focus on their synthesis, self-assembly, and applications. In this article, for convenience of the readers, various POSS based amphiphilic polymers have been grouped into telechelic, hemitelechelic, esotelechelic, block copolymers, random copolymers, and star-like polymers. Their synthesis, self-assembly, particularly in aqueous medium, and their potential applications in various fields are thoroughly reviewed.

Nanohybrid (phPOSS- f -CNTs) based on Carbon Nanotubes (CNTs) and Phenyl Polyhedral Olygomenric Silsesquioxane (phPOSS) have been synthesized to be used as multifunctional filler for polymer nanocomposites. The success of the functionalization procedure has been demonstrated via accurate spectroscopic, spectrometric and thermo-gravimetric analyses. The results reveal that a large portion of phPOSS is covalently linked to CNTs, while a small amount of phPOSS remains physically adsorbed due to the strong interactions coming from π electron coupling between the CNTs and phenyl rings in phPOSS. Small amounts (1 wt.%) of phPOSS- f -CNTs have been dispersed in Ultra High Molecular Weight Polyethylene (UHMWPE), aiming at improving the photo-stability of the resulting nanocomposite. The rheological and thermo-mechanical behavior of UHMWPE/phPOSS- f -CNTs nanocomposite reflects two different opposite contributions, namely the reinforcement effect of CNTs and the plasticizing action of phPOSS molecules. Concerning the photo-oxidative behavior, phPOSS- f -CNTs show a remarkable protective ability, which is absolutely much higher than those exerted by CNTs and phPOSS molecules when added one by one. Such unexpected results could be explained considering (i) a synergic effect between phPOSS and CNTs, (ii) the possibility of phPOSS to act at the polymer–nanoparticles interface, which is a critical region for the degradation processes, and (iii) the formation of a phPOSS-rich layer that may hinder the oxygen diffusion within the polymeric matrix.

We report a selective immobilization strategy to control the catalytic performance of the target active species in hybrid multisite catalysts. The sterically bulky and electronically donated polyhedral oligomeric silsesquioxane (POSS) is introduced onto the support and offers extra immobilization sites for the target pre-catalyst. DFT and CO low-temperature adsorption facilitate to understand the distribution of active sites. The nickel pre-catalyst can interact with the POSS, endowing the scattered distribution of nickel sites. The large steric and electronic donated iron pre-catalyst exhibits the inertness to POSS, confining iron species on the POSS-free space. The selective dispersion of nickel species enhances its contribution in the synthesis of UHMWPE fraction with an exceptional activity, a much higher molecular weight and branching degree. This promoted contribution synchronously enhances the impact resistance (+27%), tensile strength (+53%), Young’s modulus (+111%) and elongation ratio (+37%) of the synthesized bimodal PE compared to those of commercial UHMWPE.

A photoresponsive hydrogel consisting of stilbene dye (Sti; 4,4′-disubstituted stilbene), an 8-armed core molecule (POSS; polyhedral oligomeric silsesquioxane having eight amino groups), and bifunctional poly(ethylene glycol) (PEG) showed large and fast deformation derived from its highly symmetrical structure in aqueous media. The polymeric hydrogel with an 8-armed POSS (POSS-Sti; cross-linked polymer obtained from polycondensation reaction between POSS and PEG-modified Sti) showed a large deformation upon photostimulation (UV-A (λ = 350 nm) and UV-C (λ = 280 nm)). The bending deformation can be repeated at least ten times. On the other hand, the control hydrogel without Sti dye (POSS-PEG; polymer prepared from the polycondensation reaction between POSS and PEG) did not show any deformation upon photoirradiation. However, the TPEG-Sti hydrogel (Sti cross-linked with a 4-armed core molecule (TPEG; tetra-armed poly(ethylene glycol))) showed a smaller deformation compared to the POSS-Sti hydrogel with the 8-armed core molecule. The larger deformation of the POSS-Sti hydrogel was discussed in detail. The photoisomerization of the Sti units drives swelling/shrinking and the change in the Young’s modulus of the POSS-Sti hydrogel upon UV irradiation, where a stacked assembly of the Sti dye molecules acts as a cross-linking point. The photoisomerization of the Sti dye results in the association/dissociation of the Sti assembly, and the increase/decrease in the cross-linking density dramatically alters the volume of the POSS-Sti hydrogel, causing the efficient assembly of the Sti units because of their highly symmetric structure and the high density of the Sti dye derived from the 8-armed POSS core structure.

Herein, the nanostructured block copolymers (BCPs) of fluorinated methacrylate and POSS-methacrylate were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. In this case, methacryloisobutyl polyhedral oligomeric silsesquioxane (MAibPOSS) was first polymerized using 2-cyano-2-propyl dodecyl trithiocarbonate (CPDTC) as a RAFT agent. Later, the poly(methacryloisobutyl polyhedral oligomeric silsesquioxane) (PMAibPOSS) was used as a macro-RAFT agent for the polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) monomer. The BCPs were characterized via FT-IR, 1H NMR and GPC analyses. The BCPs spontaneously self-assembled exhibiting core-shell and lamellar type nanostructures when deposited from different organic solvents like chloroform and THF, respectively. The nanostructured morphology of the BCPs was studied using SEM, TEM, AFM, and SAXS analyses. The prepared BCPs were coated over various substrates and their hydrophobicity was measured using water contact angle analysis. The coated substrates exhibited improved hydrophobicity with the water contact angle values as high as ~135°.

Functionalized graphene oxide sheets (FGO) with improved dispersive and smoke-suppressive properties were synthesized by covalently grafting octa (propyl glycidyl ether) polyhedral oligomeric silsesquioxane on graphene oxide sheets (GO) with γ-aminopropyl triethoxysilane as a chemical bridge. The good dispersion of FGO sheets in the epoxy resin (EP) matrix endowed EP composites with stable thermal resistance, enhanced tensile and smoke-suppressive properties. Cone calorimeter tests indicated that the addition of 0.7 wt% FGO sheets to EP composites reduced the peak of heat release rate, total heat release, and total smoke release by 49.7%, 34.3%, and 41.5%, respectively. Two important effects that originated from FGO promoted this improvement; that is, well-dispersed FGO sheets exhibited a tortuous effect by lengthening the heat path and inhibiting heat diffusion in the EP matrix, and the increase in char residue and the reduction in gas volatiles confirmed the barrier effect of FGO sheets by forming protective char structures on the surface of the matrix, which restrained smoke release. This method provided a feasible concept for effectively enhancing the flame retardancy of EP composites by combining the characteristics of graphene and polyhedral oligosilsesquioxane through the construction of effective interfacial interactions.

Hybrid hydrogel materials derived from two types of polymethacrylates: rigid and flexible, crosslinked with methacryloxy-multifunctionalized polyhedral oligomeric silsesquioxane (M-POSS) were obtained in a photo-induced copolymerization process. The base monomers were 2-hydroxyethyl methacrylate (HEMA; forming a rigid polymer) and a mixture of oxyethylene glycol (di)methacrylates (forming an elastomer). Investigations included the kinetics of hybrid materials formation and selected physical and mechanical properties. The obtained results were discussed in terms of effects of H-bonding and viscosity of compositions before curing, additional crosslinking, the presence of POSS cage, M-POSS aggregation and rigidity/flexibility of the base polymer. It was found that physical factors (diffusion, tendency to aggregation) dominate over interactions between reacting molecules (H-bonding) during the formation of the hybrid polymer structure. Disorder in H-bonding in HEMA-based material is responsible for the appearance of the antiplasticization effect manifesting itself by the lowering of the Tg value with simultaneous increase in the Young modulus. Antiplasticization behavior affects also thermal stability of the HEMA-based materials. In general, cross-linking of the rigid and elastomeric material with M-POSS gives quite different results; moreover, the HEMA-based materials show an exceptional behavior. The results presented are important indications in the selection of technological curing parameters in preparation of M-POSS-containing hydrogel materials.

Thermostable nanocomposites based on densely cross-linked Cyanate Ester Resins (CER), derived from bisphenol E and doped by 0.01–10 wt.% epoxycyclohexyl-functionalized polyhedral oligomeric silsesquioxane (ECH-POSS), were synthesized and characterized in detail by means of TEM, SAXS, EDXS, FTIR, DSC, DMA, TGA, far-IR and creep rate spectroscopy techniques. It was revealed that ultra-low POSS contents (≪1 wt.%), covalently embedded into CER network, substantially changed its nanostructure and properties. This resulted in changing network dynamics; increasing glass transition temperatures by 20–50 °C; enhancing high temperature elastic and creep resistance properties, and increasing thermal stability under inert atmosphere at T

Synthesis, characterization and solution behavior of tadpole-shaped amphiphilic polymers with hydrophobic polyhedral oligomeric silsesquioxane (POSS) chain-end and hydrophilic main-chain having leucine pendants were investigated. Reversible addition-fragmentation chain transfer (RAFT) polymerization technique was employed to polymerize tert-butyloxycarbonyl- l -leucine methacryloyloxyethyl ester (Boc-Leu-HEMA) in the presence of POSS based RAFT agent. The POSS content and molecular weight of polymers could be controlled while maintaining a narrow molecular weight distribution (

The effect of silsesquioxane coating of aluminium oxide nanoparticles on their dispersion and on the interfacial strength between nanoparticles and polymer matrix in low-density polyethylene compos ...

Microcontact printing (μCP) is a widely used technique for depositing proteins in micro patterns. The investigation of protein–protein interactions in small cells like T-cells (5–10 μm), however, require feature sizes in the nanometer range which could be created by nanocontact printing (nCP). The main intention of our work was to develop functionalized Polyhedral Oligomeric Silsesquioxane (POSS) materials as an alternative for poly(dimethylsiloxane) (PDMS) which are commonly used as stamp material for micro-contact printing. POSS materials combine many desirable properties of conventional organic and inorganic components and provide an exemplary core system for developing versatile functional resist materials. Their properties are easily tunable by molecular design to suit the desired application. Used as stamp material POSS combines the advantages of hard stamps for high resolution printing and the possibility to tune the surface chemistry to enable a proper transfer of proteins. In this work, epoxy as well as carboxylic acid functionalized POSS were synthesized and epoxy–carboxylic acid bi-functionalized POSS materials have been developed for nCP stamp applications. The POSS polymers were designed by incorporating the necessary functional groups onto the silsesquioxane cage via platinum catalyzed hydrosilylation chemistry. The presence of epoxy groups allows the resists to polymerize at room temperature under UV-light exposure, while carboxylic acid groups ensure the presence of anionic species (COO−) at the surface of the stamps to facilitate protein transfer. The as-synthesized materials were characterized and supposed structures of the cured materials were confirmed by spectroscopic methods. Via nCP a monolayer of nanoscale avidin patterns have been deposited on epoxy-functionalized glass substrates.

Copolymers comprising styrene and polyhedral oligomeric silsesquioxane-derived methacrylate (PS- co -PMAPOSS) of various MAPOSS:styrene ratios with Mn over 100 kDa were prepared by concurrent ARGET ATRP–RAFT. Fibrous mats of the synthesized copolymers are then fabricated through electrospinning process using various conditions (solvents and POSS content). The results from SEM and EDS analysis unveiled the fibers’ physical and chemical characteristics as a clear footprint of the influence of solvent selection (tetrahydrofuran (THF) and dimethylformamide (DMF)). It is evident that liquid–liquid phase separation followed by phase segregation of PS and POSS constitute to the varying degree of porosity in the electrospun fibers. Finally, preliminary tests suggest that highly porous PS- co -PMAPOSS fiber can be modified with high temperature, plasma and silanization for further novel applications.

In this work, a novel and efficient approach for the compatibilization of poly(lactide) (PLA) and poly(e-caprolactone) (PCL) immiscible blends, consisting in the addition of ad hoc functionalized polyhedral oligomeric silsesquioxane (POSS) molecules, was investigated. To this purpose, different kinds of POSS were exploited: one without specific functionalities (named POSS-oib) and another one characterized by hydroxyl groups (named POSS-OH) potentially capable of making the silsesquioxane compatible with both the polymer matrices. Moreover, in order to improve the silsesquioxane adhesion to the components of the blend, an amino-functionalized POSS was subjected to the grafting of a poly(e-caprolactone)- b -poly( l -lactide) diblock copolymer (POSS-PCL- b -PLLA) by means of ring opening polymerization. The above silsesquioxanes were loaded into PLA/PCL blends through melt blending. SEM characterization showed that the POSS molecules are capable of modifying the blend morphology to different degrees. In particular, the synthesized POSS-PCL- b -PLLA nanohybrid proved very effective at ameliorating the compatibility of PLA/PCL blends by preventing the dispersed domains from coalescence, despite the small amount of silsesquioxane (2 wt.%), and consequently of diblock copolymer, added to PLA/PCL blend. The peculiar co-continous phase morphology, promoted at the interface by the presence of the above POSS, was found to enhance the mechanical properties of the blend, improving the elongation at break without reducing its Young’s modulus. Our study demonstrated that not only the microstructure but also the thermal properties of the blends were significantly affected by the presence of silsesquioxane molecules dispersed in the blend.

A novel POSS-based organic–inorganic hybrid aerogel were synthesized through Schiff base chemistry using Octa(aminophenyl)silsesquioxane and aldehyde as raw materials. The chemical structures were characterized by fourier transform infrared (FTIR), solid-state 13C and 29Si nuclear magnetic resonance. The results showed that the POSS building blocks are successfully weaved in the network without any alteration of the POSS structural characteristics. The morphology and surface properties of the resultant aerogels were investigated by field-emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and the Brunauer–Emmett–Teller (BET) method. The results showed that the aerogels possessed a fine microstructure with a high specific surface area of 855 m2 g−1.

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.

In this work, a novel initiator bearing heptaphenyl polyhedral oligomeric silsesquioxane (POSS) was synthesized via the copper-catalyzed Huisgen 1,3-cycloaddition (i.e., click chemistry). With this initiator, the atom transfer radical polymerization (ATRP) of N -isopropylacrylamide (NIPAAm) was carried out to afford the POSS-capped PNIPAAm. The organic–inorganic amphiphiles were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Atomic force microscopy (AFM) showed that the POSS-capped PNIPAAm amphiphiles in bulk displayed microphase-separated morphologies. In aqueous solutions, the POSS-capped PNIPAAm amphiphiles were self-assembled into micelle-like aggregates as evidenced by dynamic light scattering (DLS) and transmission election microscopy (TEM). It was found that the sizes of the self-organized nanoobjects decreased with increasing the lengths of PNIPAAm chains. By means of UV–vis spectroscopy, the lower critical solution temperature (LCST) behavior of the organic–inorganic amphiphiles in aqueous solution was investigated and the LCSTs of the organic–inorganic amphiphiles decreased with increasing the percentage of POSS termini. It is noted that the self-assembly behavior of the POSS-capped PNIPAAm in aqueous solutions exerted the significant restriction on the macromolecular conformation alteration of PNIPAAm chains while the coil-to-globule collapse occurred.

In this work, we reported the synthesis of a dodecahydroxyl-functionalized macrocyclic oligomeric silsesquioxane (MOSS). The novel 24-membered hydroxyl-functionalized MOSS was employed as a macroinitiator for the ring-opening polymerization of e-caprolactone (CL) and the organic–inorganic macrocyclic molecular brushes with poly(e-caprolactone) (PCL) side chains were successfully synthesized. The organic–inorganic macrocyclic molecular brushes were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). The results of wide angle X-ray diffraction (XRD) indicate that the architecture of the organic–inorganic macrocyclic molecular brushes did not alter the structure of PCL crystals. Differential scanning calorimetry (DSC) shows that the architecture of organic–inorganic macrocyclic molecular brushes significantly affected the rearrangement of PCL crystals. Compared to linear PCL, the organic–inorganic macrocyclic molecular brushes possessed the improved thermal stability in terms of the temperatures at the maximum of degradation rate and the yields of degradation residues.

The star-shaped organic/inorganic hybrid poly( l -lactide) (PLLA) based on polyhedral oligomeric silsesquioxane (POSS) was prepared using octa(3-hydroxypropyl) polyhedral oligomeric silsesquioxane as initiator via ring-opening polymerization (ROP) of l -lactide (LLA). The molecular weight of POSS-containing star-shaped hybrid PLLA (POSSPLLA) can be well controlled by the feed ratio of LLA to initiator. The POSSPLLA was further functionalized into the macromolecular reversible addition-fragmentation transfer (RAFT) agent for the polymerization of N -isopropylacrylamide (NIPAM), leading to the POSS-containing star-shaped organic/inorganic hybrid amphiphilic block copolymers, poly( l -lactide)– block –poly( N -isopropylacrylamide) (POSS(PLLA– b –PNIPAM)). The self-assembly behavior of POSS(PLLA– b –PNIPAM) block copolymers in aqueous solution was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). DLS showed the PNIPAM block in the aggregates is temperature-responsive and its phase-transition is reversible. TEM proved that the star-shaped POSS(PLLA– b –PNIPAM) amphiphilic block copolymers can self-assemble into the vesicles in aqueous solution. The vesicular wall and coronas are composed of the hydrophobic POSS core and PLLA, and hydrophilic PNIPAM blocks, respectively. Therefore, POSSPLLA and POSS(PLLA– b –PNIPAM) block copolymers, as a class of novel organic–inorganic hybrid materials with the advantageous properties, can be potentially used in biological and medical fields.

This paper deals with the preparation of PP/polysilsesquioxane blends and their study to investigate silsesquioxane dispersion, mechanical properties, thermal stability and combustion properties by means of a number of techniques, such as SEM, XRD, Rheology, TGA, DSC, Cone Calorimeter tests and LOI. Polysilsesquioxane with different organic groups (methyl, vinyl or phenyl) were used; both dispersion and final properties were found to be dependent on the silsesquioxane organic fraction type. The PP/polysilsesquioxane blends showed an increased thermoxidative stability and combustion resistance, in terms of lower rate of heat release. Higher mechanical performances were also achieved with PP/vinyl polysilsesquioxane, with higher elastic modulus as well as higher elongation at break.

This paper presents the results of morphological and ac electrical investigations on low density polyethylene (LDPE) composites with octavinyl polyhedral oligomeric silsesquioxane (POSS). It has been shown that at low loadings, the frequency dependence of dielectric constant and dielectric loss for the LDPE/POSS composites showed unusual behaviors when compared with conventional (micro-sized particulates) composites. The ac breakdown strength was measured and statistical analysis was applied to the results to determine the effects of POSS loadings on the dielectric strength of LDPE. The morphological characterization showed that the presence of POSS additives apparently altered the supermolecular structure of LDPE and resulted in more homogeneous morphology when compared with the neat LDPE. The structure–property relationship was discussed and it was concluded that the final dielectric properties of the composites were determined not only by the incorporation of POSS additives but also by the supermolecular structure of LDPE. Rheological analyses of LDPE/POSS composite were also performed and the results showed that the octavinyl-POSS had good compatibility with LDPE.

Poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 6 (PPO/PA6) (50/50 w) blends filled with epoxycyclohexyl polyhedral oligomeric silsesquioxane (POSS) were prepared via melt-mixing. The reactions between POSS and PPO/PA6 blends were studied by Fourier transform infrared spectroscopy, end group and gel content tests. The morphology of PPO/PA6/POSS composites was observed by field emission scanning electron microscope and transmission electron microscope. As a chain extender and a crosslinking agent for PA6, POSS largely affected the morphology of the composites, which was mainly dependent on the melt-viscosity ratio and interfacial tension between the components. With increasing POSS content from 2 to 4 phr, the morphology of the composites transformed from droplet/matrix to co-continuous morphology. The PPO/PA6/POSS composites with co-continuous morphology had the better mechanical properties than those with droplet/matrix morphology. Dynamic mechanical thermal analysis showed that the addition of POSS increased the T g of PA6.

In this work, the morphology and thermo-mechanical behaviour of nanocomposites formed by a polycarbonate (PC) matrix and polyhedral oligomeric silsesquioxane with phenethyl substituents (Ph-POSS) have been studied. The Ph-POSS nanocages were added to the PC by direct melt blending at loadings between 0% and 15 wt%. Good dispersion was achieved up to 5 wt% of nanofiller. At higher loadings micron-sized aggregates were observed in the nanocomposites by scanning and transmission electron microscopy. Increasing of Ph-POSS content lead to phase separation, agglomeration and low values on the final properties. The DSC and DMA analyses showed that increasing the amount of nanocages caused a continuous decrease on the composite’s Tg. Although little increments on the polycarbonate decomposition temperature were found, the presence of Ph-POSS did not improve significantly the thermal stability. Under nitrogen atmosphere the degradation mechanism of PC was not affected by the POSS. The residual weights obtained under oxygen atmosphere were in agreement with the theoretical weights of the Ph-POSS added. With respect to the nanocomposites mechanical properties the most remarkable trend was an improvement on the composite’s yield stress having the maximum at 5 wt% of nanofiller. Higher amounts of Ph-POSS lead to a decrease on the yield stress, finding even lower values than the one corresponding to the neat matrix. This behaviour has been attributed to the presence of large POSS agglomerates with low adhesion to the polymer matrix. A continuous decrease on the strain at break was also observed, reflecting the brittle character of the formed composites.

An organic–inorganic hybrid copolymer was prepared by using a C2 symmetric ansa-metallocene catalyst in conjunction with modified methylaluminoxane (MMAO). Two kinds of monovinyl substituted polyhedral oligomeric silsesquioxane (POSS) monomers were used to copolymerize with propylene. A special experiment was carried out in order to confirm the purification of the copolymerization products. The unreacted monomer was completely removed by washing with an n-hexane/ethanol mixture. Thermal properties of the propylene/POSS copolymers exhibited improved thermal stability with higher degradation temperature and char yields, demonstrating that the inclusion of inorganic POSS nanoparticles made the organic polymer matrix more thermally robust.