Oligomeric Silsesquioxane Research Articles

Structure–property relationships and nanofiller‐induced hydro‐anti‐plasticization in polyhydroxyurethane/POSS hybrid composites

AbstractNon‐isocyanate polyhydroxyurethanes/polyhedral oligomeric silsesquioxane (PHU/POSS) hybrid composites are prepared by in situ physical introduction of octa(3‐hydroxy‐3‐ethylbutyldimethylsiloxy) POSS into a linear non‐isocyanate polyhydroxyurethane matrix. The amorphous nature of the matrix is retained in the composites and no POSS crystals are observed. Thermal and mechanical properties are studied along with water‐polymer interactions and are discussed in terms of structure‐properties relationships. POSS has only minimal effect on thermal stability. Composite materials with up to 2 wt% POSS exhibit an increased rubbery modulus. The glass transition temperature of the composite materials increases up to 2 wt% loading and decreases at higher POSS content. Water‐polymer interactions are studied in a broad range of relative humidity (0–0.97). Materials exhibit a relatively high water absorption, which is enhanced by POSS at low concentrations. Moisture sorption isotherms are discussed in terms of the Guggenheim‐Anderson‐de Boer model. The study of molecular mobility of hydrated systems by differential scanning calorimetry reveals a peculiar POSS‐induced antiplasticization in PHU/POSS blends at 10–20 wt% water uptake, possibly due to the formation of POSS‐centered water clusters.

Green crosslinking strategy for ethylene-vinyl acetate rubber composites with NH2-POSS as a crosslinking agent and reinforcing nanofiller

Ethylene-vinyl acetate rubber is extensively utilized in various fields including electrical wires and cables, automotive, and electronic components. Traditional peroxide vulcanization methods, however, release volatile organic compounds, posing environmental pollution concerns. To address this, 3-amino-polyhedral oligomeric silsesquioxane (NH2-POSS) was synthesized through hydrolytic condensation and used both as a crosslinking agent and a filler in the preparation of ethylene-vinyl acetate-glycidyl methacrylate terpolymer (EVM-GMA) composites. Notably, NH2-POSS not only effectively crosslinks EVM-GMA, but also thus promotes the dispersion of the silica in the composites. EVM-GMA/silica composites crosslinked by NH2-POSS display superior mechanical properties and thermal stability compared to EVM-GMA/silica composites crosslinked by organic peroxide. EVM-GMA composite with 4.5 phr NH2-POSS and 30 phr SiO2 has a tensile strength of 10.7 MPa and an elongation at the break of 240 %. This study introduces a novel and environmentally friendly crosslinking strategy for producing high-performance EVM-GMA composites without additional additives.

Preparation and study of novel UV‐curable alkyd‐siloxane coating materials

AbstractA material capable of curing due to UV irradiation based on an alkyd oligomer and oligoorganosilsesquioxanes (OOSs) with functional thiol groups was obtained. Using microinterferometry, it was shown that the alkyd oligomer and OOS are completely compatible (mutually soluble). The resulting alkyd‐siloxane composition was cured under the action of UV irradiation due to reaction between double bonds of alkyd oligomer and thiol‐groups of silsesquioxane oligomer. The curing reaction takes 5 min with formation of coating, containing 99% of gel fraction, which is in 30 times faster in comparison with the classical method of alkyd curing in the presence of siccatives. The hydrophobicity of alkyd‐siloxane coatings also increases and varies depending on the content of OOS. The introduction of 50% OOS into the alkyd oligomer makes it possible to increase the water contact angle by 10° relative to the coating based on pure alkyd. A similar dependence is observed when studying the thermal stability of coatings. Thus, even with the introduction of 10% OOS into alkyd oligomer, the temperature at which a loss of 50% of mass occurs increases by 24°C relative to coatings based on a pure alkyd oligomer.

Fabrication of CsPbBr3 nanocrystal/POSS-based copolymer films for non-contact temperature probes

Fluorescence-based non-contact temperature measurement has been attested a widely-used technique for temperature aware in rotating mechanical equipment, electrical devices, and other fields. Inspired by the thermal sensitivity of perovskite nanocrystals, we prepared a CsPbBr3/polyhedral oligomeric silsesquioxane (POSS)-based composite film with outstanding temperature-photoluminescence (PL) dependence, high reversibility, and high hydrophobicity. Perovskites nanocrystals with controllable nanocubic and nanoplate morphologies were synthesized by adjusting the temperature. Various CsPbBr3/POSS-based composite films with different CsPbBr3 morphologies and ratios were fabricated. The CsPbBr3 nanocubic and nanoplate based films possessed high hydrophobicity, UV stability, and thermal stability. Temperature dependence experiments revealed that PL spectral parameters of CsPbBr3/POSS-based composite films had obvious temperature change characteristics attributable to the CsPbBr3 morphology. The PL intensity and full width at half maximum (FWHM) of the CsPbBr3 nanoplate based film exhibited poor regularity with temperature. In contrast, the PL intensity of the CsPbBr3 nanocubic based film was related to temperature exponentially, and the FWHM had a strong linear relationship with temperature. Moreover, temperature dependence reversibility was realized for the CsPbBr3 nanocubic based film. Furthermore, the applicability of a CsPbBr3 nanocubic based temperature probe was verified by monitoring the temperature of a bearing cage on a spindle-bearing test platform. The CsPbBr3/POSS-based composites can be applied as temperature probes for non-contact temperature measurement of rotating components of mechanical equipment.

O167: 3D-TIPS Printed Nanohybrid Composite Vascular Grafts for Evaluation of Human Umbilical Vein Endothelial Cell Response

Abstract Introduction Cardiovascular disease is a global killer. For progressive disease coronary artery bypass grafting is used, which is limited by suboptimal vasculature and patency. Alternatively, tissue engineered scaffolds are cell seeded structures supporting neovascularization. Poly(ethylene-diethylene glycol succinate)urea-urethane-polyhedral oligomeric silsesquioxane [P(EDS)UU-POSS] shows potential for its elastic and degradation properties. In this study, we manufacture a P(EDS)UU-POSS scaffold and assess human umbilical vein endothelial cell (HUVEC) attachment. Method 3D printed thermally induced phase separated (3DTIPS) scaffolds were manufactured. Mechanical testing was employed to compare scaffold stress-strain curves with those of currently utilised vessels and synthetic grafts. HUVEC were seeded onto scaffolds coated with type I collagen and peptide hydrogel respectively. Surface functionalization in this way, is hypothesised to optimise cell attachment. Assessment of cell viability was with PrestoBlueTM and total DNA assay. Confocal imaging was also performed. Results Tensile properties of 3D-TIPS scaffolds match the greater saphenous vein. 3D-TIPS scaffolds exhibit higher elasticity than synthetic PCL grafts, meeting stretch and strength requirements of vessels. Metabolism data shows an initial increase followed by a decrease for both types of coating. This indicates a decrease in overall metabolism but not cell death, attributed to cellular adaptation to the scaffold microenvironment, with collagen coating performing better. Visualisation of type I collagen samples demonstrates increases in cellular attachment. Conclusions There is potential for optimised 3DTIPS P(EDS)UU-POSS scaffolds with suitable mechanical properties. Further study of HUVEC and smooth muscle cell co-culture will better mimic in vivo environments, assessing sustained potential as vascular grafts.

Fluorinated‐polyhedral oligomeric silsesquioxane (F‐POSS) functionalized halloysite nanotubes (HNTs) as an antifouling additive for epoxy resin

AbstractAntifouling epoxy resin serves as a member of advanced nanocomposite coatings and engineered surfaces. Nevertheless, developing an antifouling epoxy composites is a state‐of‐the‐art technology. Herein, a complex nanostructure is tailored to be served as an advanced additive giving the antifouling characteristics to the epoxy resin. F‐POSS@HNT hybrid nanostructure, that is, halloysite nanotubes (HNTs) decorated with fluorinated polyhedral oligomericsil sesquioxane (F‐POSS), was synthesized and characterized. Chemical structure changes, thermal stability and morphology of hydroxylated HNTs (hHNTs) intermediate and F‐POSS@HNT ultimate nanostructures were analyzed by FTIR spectroscopy, TGA and TEM, respectively. The F‐POSS@HNTs catalyzed the epoxy‐amine crosslinking reaction, taking “Good” or “Excellent” crosslinking tags an quantified by the “Cure Index.” The apparent activation energy values were calculated for the epoxy (reference), epoxy/hHNTs, and epoxy/F‐POSS@HNTs systems (26, 51, and 47 kJ mol−1, respectively). Contact angle measurements were performed via dynamic tests demonstrating improved hydro‐ and oleophobicity of the thermoset composites. The advancing contact angle with diiodomethane increased 36% and 30% for nanocomposites containing 5 and 10 wt.% of the developed hybrid nanostructure, respectively, compared with the neat epoxy. Likewise, 54% and 67% reduction in paraffin fouling in the same order confirmed their antifouling ability. Regarding self‐cleaning characteristics, 24% and 33% surface recovery were observed, respectively.Highlights Antifouling surface was achieved in epoxy thermoset nanocomposites for potential industrial applications. Self‐cleaning behavior correlated with low wetting and antifouling properties. F‐POSS@HNT nanofillers were synthesized and successfully added to epoxy matrix. Both hHNT and F‐POSS@HNT showed a beneficial autocatalytic effect on epoxy‐amine reaction yielding satisfactory polymer crosslinking. Activation energy was reduced by incorporating F‐POSS@HNT compared with hHNT, signature of facilitated crosslinking.

High Wear Resistance of POSS Grafted-Polyimide/Silica Composites under Atomic Oxygen Conditions.

Polyimide-bearing retainer has been successfully used in space environment. However, the structural damage of polyimide induced by space irradiation limits its wide use. In order to further improve the atomic oxygen resistance of polyimide and comprehensively investigate the tribological mechanism of polyimide composites exposed in simulate space environment, 3-amino-polyhedral oligomeric silsesquioxane (NH2-POSS) was incorporated into a polyimide molecular chain and silica (SiO2) nanoparticles were in situ added into polyimide matrix and the combined effect of vacuum environment, and atomic oxygen (AO) on the tribological performance of polyimide was studied using bearing steel as the counterpart by a ball on disk tribometer. XPS analysis demonstrated the formation of protective layer induced by AO. The wear resistance of polyimide after modification was enhanced under AO attack. FIB-TEM confirmed that the inert protective layer of Si was formed on the counterpart during the sliding process. Mechanisms behind this are discussed based on the systematic characterization of worn surfaces of the samples and the tribofilms formed on the counterbody.

Multiscale Textured Mesh Substrates that Glide Alcohol Droplets and Impede Ice Nucleation

Textured surfaces are commonly designed to preclude wetting by water. The design of surfaces that are not wetted by alcohols represents a considerable challenge given the low surface tension, viscosity, and density of these liquids. Herein, a hierarchically textured plastronic architecture that can suspend alcohol droplets in a metastable Cassie–Baxter regime is presented. As a result of microtexturation of the underlying stainless steel mesh, multiscale texturation derived from ZnO tetrapods, and surface functionalization with perfluorinated‐polyhedral oligomeric silsesquioxanes, the surfaces glide aliphatic alcohols, water, andn‐hexadecane. The design of surfaces not wetted by alcohols is particularly relevant to “point‐of‐care” environments. Because of the minimized interfacial contact areas, the textured surfaces further greatly inhibit ice nucleation at solid/liquid interfaces. High‐speed video imaging of the freezing and droplet impact shows that the textured surfaces delay ice nucleation by inhibiting heterogeneous nucleation, more effectively channel kinetic energy upon droplet impact to break up impinging droplets, and greatly limit frost formation. Once ice forms, its adhesion is substantially diminished by about three orders of magnitude as compared with planar substrates. The results demonstrate a scalable spray deposition method to generate surfaces for enabling the deterministic flow of liquids as well as inhibit ice formation.

3D-printed porous PEEK scaffold combined with CSMA/POSS bioactive surface: A strategy for enhancing osseointegration of PEEK implants

As an attractive biomaterial for orthopedic implants , polyetheretherketone (PEEK) has many prominent characteristics such as good biocompatibility and biomechanical properties , as well as natural radiolucency. However, the potential clinical application is limited due to its biologically inert surface and poor osseointegration . To solve this problem, we fabricate a macroporous PEEK scaffold modified with methacrylated chitosan/polyhedral oligomeric silsesquioxane (CSMA/POSS) nanocomposite through 3D printing , sulfonation and UV-induced graft polymerization. The water contact angle, protein adsorption ability and biomineralization study of the sulfonation-treated PEEK (SPEEK)-CSMA/POSS scaffolds were measured in order to evaluate the surface properties. The results indicated that CSMA/POSS as a bioactive microporous surface integrated with nanoparticles promoted the protein adsorption and apatite formation . For the in vitro and in vivo evaluation of the osteogenicity, rat bone marrow mesenchymal stem cells (rBMSCs) and rat calvaria defect repair model were used. Biological results showed that the 3D porous structure and bioactive surface of modified PEEK scaffolds provided a suitable condition for cell adhesion and proliferation, enhanced the osteogenic differentiation of rBMSCs and promoted osteogenesis in vivo compared to the untreated PEEK scaffold. Therefore, 3D-printed macroporous PEEK scaffold modified with CSMA/POSS bioactive microporous surface represents a promising modification strategy for enhancing osseointegration of PEEK implants.

Preparation of Bio‐Based Polybenzoxazine/Pyrogallol/Polyhedral Oligomeric Silsesquioxane Nanocomposites: Low Dielectric Constant and Low Curing Temperature

AbstractIn this work, a bio‐based benzoxazine monomer (C‐s) is synthesized from cardanol, stearylamine, and paraformaldehyde through solvent‐free method. Pyrogallol is used as a curing catalyst for the ring‐opening polymerization of benzoxazine. Differential scanning calorimeter (DSC) results reveal that doping with pyrogallol reduces the exothermic peak temperature (Tp) of C‐s from 256 to 174 °C. The polybenzoxazine/pyrogallol/polyhedral oligomeric silsesquioxane (PC‐s/py/POSS) nanocomposites are prepared via thermal curing. The doping of aminopropyl isobutyl POSS (POSS‐NH2) can reduce the dielectric constant of polybenzoxazine. The dielectric constant of PC‐s/py/POSS is 2.64 at 1 MHz when the doping amount of POSS‐NH2 is 10 wt%. The results of thermogravimetric analysis (TGA) and water absorption test indicate that the PC‐s/py/POSS nanocomposites possess good thermal stability and water resistance. In summary, the PC‐s/py/POSS nanocomposites with low curing temperature and low dielectric constant are expected to be applied to the low dielectric materials for microelectronic applications.

Reactive Amphiphilic Aprotic Ionic Liquids Based on Functionalized Oligomeric Silsesquioxanes

Abstract This paper discusses a method for the synthesis of ionic liquids which are mixtures of oligomeric silsesquioxanes (OSS) of polyhedral structure and their analogs with open chains containing aprotic cationic ionic groups with different lengths of alkyl substituents and reactive hydroxyl groups in the organic shell (OSS-ILs). This method includes the quaternization reaction of OSS with tertiary amine and primary and secondary hydroxyl groups by n-bromopropane or n-bromodecane. Obtained compounds were amorphous with glass transition temperature below 0 °C. The ionic conductivity of OSS-ILs increases with decreasing the alkyl substituent length and reaches 1.4·10−3 S/cm at 120 °C. Dynamic light scattering reveals that the length of alkyl substituent of OSS-ILs affects the assembly behavior in aqueous solutions. According to atomic force microscopy images, the surface morphology of the film of OSS-IL with short substituents showed disk-like flat micelles with an average diameter of 229 ± 92 nm and height of 2 nm. OSS-IL with long substituents formed polydisperse micellar morphologies, of which a majority showed elongated, worm-like structures with an average height of 2 nm. The ability to endow ionic conductivity and to tune morphology makes these materials promising as potential polymer electrolytes for various electrochemical applications, in particular ionic sensors and energy storage devices.

Synthesis and Steady State Photophysical Property Analysis of Beads on a Chain (BoC) Silsesquioxane Oligomers Containing Arene and Heteroarene Cross-linkers

Synthesis and Steady State Photophysical Property Analysis of Beads on a Chain (BoC) Silsesquioxane Oligomers Containing Arene and Heteroarene Cross-linkers

Coordination Polymers Based on Amphiphilic Oligomeric Silsesquioxanes and Transition Metal Ions (Co2 +, Ni2+): Structure and Stimuli‐Responsive Properties

AbstractSynthesis, structural organization, thermal, and magnetic properties of coordination polymers (OSS‐polymer‐Me) based on amphiphilic oligomeric silsesquioxanes (OSS) and transition metal ions (Co2+, Ni2+) are reported. The initial amphiphilic OSS containing various ratios of n‐octadecylurethane and carboxyl groups (OSS‐C18H37‐x‐COOH‐y) are characterized with two types of ordered phases. The first one is a supramolecular structure stabilized by hydrogen bonds and characterized with a specific endothermic transition on differential scanning calorimetry thermograms (Tm1). The second one is presented by crystalline domains of aliphatic chains with a melting transition peak (Tm2). Inclusion of metals has no effect on the magnitude of Tm2 while leading to a decrease in the value of the Tm1 in comparison to the same compounds without metal. Being located in the nodes of the irregular network structure of OSS‐polymer‐Me, metal ions form ≈2 nm clusters, which connect multifunctional molecules of OSS‐C18H37‐x‐COOH‐y in a supramolecular system similar to disordered metal‐organic framework. The OSS‐polymer‐Me nanocomposites display superparamagnetic properties determined by an adaptive behavior of the intermolecular network. The latter can be modified by the application of an external magnetic field and/or moderate heat.

Interfacial regions and network dynamics in epoxy/POSS nanocomposites unravelling through their effects on the motion of molecular chains

Interfacial regions formed by incorporating a certain percentage of nanofillers into a polymer matrix can impact on the motion of molecular groups, chain units or chain segments, and alter molecular chain network dynamics, which is regarded as a key factor to achieve a finer degree control of dielectric properties of polymer nanocomposites. It is of interest to investigate the molecular chain motion behavior at interfacial regions with the incorporation of nanofillers. Epoxy resin/polyhedral oligomeric silsesquioxane (EP/POSS) nanocomposites are fabricated and the observations of morphology structure and chemical elements indicate that POSS nanofillers are well dispersed in the matrix. Differential scanning calorimeter, dynamic thermomechanical analysis, and dielectric relaxation spectroscopy are measured to analyze the effect of nanodoping on the motion properties of molecular chain units and chain segments that satisfy the Arrhenius and Vogel-Fulcher-Tammann equations respectively. The thicknesses of interfacial regions between POSS nanofillers and EP matrix are estimated from dielectric spectra and effective relative permittivity simulations, which are around several nanometers and decrease with the increment in the nanofiller content. In addition, the dielectric spectra scaling analysis indicates that the motion of small chain units can be hindered in interfacial regions and be tuned simultaneously by the variations of molecular chain network structure and dynamics. Nevertheless, the thin interfacial regions cannot effectively restrict the orientation of long molecular chain segments during the glass transition process. The variation of chain segment orientation behavior is ascribed to the interactions among molecular chains tuned by the binding effect of POSS nanofillers.

Engineering MXene surface with POSS for reducing fire hazards of polystyrene with enhanced thermal stability

High-performance MXene-based polymer nanocomposites are highly desirable for diverse industry applications due to their exceptional mechanical, thermal and other properties. Nevertheless, it remains an intractable challenge to create flame retardant polymer/MXene nanocomposites due to the difficulty to achieve uniform dispersion of MXenes. Here, we reported a facile strategy for the surface manipulation of two-dimensional titanium carbide nanosheets (Ti3C2Tx) with 3-aminopropylheptaisobutyl-polyhedral oligomeric silsesquioxane (AP-POSS) (POSS-Ti3C2Tx) through electrostatic interactions. The POSS-Ti3C2Tx is steadily dispersed in many polar solvents. Upon incorporated into polystyrene (PS), the combined effect of AP-POSS and MXene makes the resultant PS nanocomposites exhibit significantly improved thermal and thermoxidative stability, e.g. 22 °C and 39 °C increases in the temperature at 5 wt% mass loss under nitrogen and air, respectively. Meanwhile, a 39.1 % reduction in the peak heat release rate, a respective 54.4 % and 35.6 % reduction in the peak CO production rate and the peak CO2 production rate was achieved, which are superior to those of its own and previous counterparts. This outstanding fire safety is attributed to the combination of adsorption, catalytic and barrier effects of POSS-Ti3C2Tx. Hence, as-designed functionalized MXenes can be effectively applied in PS to formulate multifunctional polymer nanocomposites attractive for wide potential applications.

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

In this study, it was aimed to investigate octavinyl‐polyhedral oligomeric silsesquioxane (OV‐POSS) incorporation into natural rubber (NR)/butadiene rubber (BR) elastomer blends as a potential compatibilizer. The effects of OV‐POSS loading levels on the thermal, mechanical, morphological, and dynamic‐mechanical properties of elastomer blends were explored. Fourier‐Transform Infrared Spectrometer (FTIR), Temperature Scanning Stress Relaxation (TSSR), and Differential Scanning Calorimetry (DSC) results revealed the conceivable effect of OV‐POSS nanoparticles in the vulcanization through reacting with sulfur and/or elastomers. Scanning Electron Microscope (SEM), X‐Ray Diffraction (XRD), and tensile test measurements supported the improvement of mechanical properties due to homogeneous dispersion at low loading levels. On the other hand, high amount of OV‐POSS incorporation (7 and 10 phr) resulted in a decrease in mechanical properties, owing to the agglomeration of nanoparticles. According to contact angle and Dynamic mechanical analysis (DMA) results, it could be concluded that OV‐POSS nanoparticles were localized at the interface of the elastomers and enabled the compatibilization of immiscible NR/BR blends.

Highly Sensitive Strain Sensor Based on a Stretchable and Conductive Poly(vinyl alcohol)/Phytic Acid/NH2-POSS Hydrogel with a 3D Microporous Structure

Conductive hydrogel-based wearable strain sensors with tough, stretchable, self-recoverable, and highly sensitive properties are highly demanded for applications in electronic skin and human-machine interface. However, currently, hydrogel-based strain sensors put forward higher requirements on their biocompatibility, mechanical strength, and sensitivity. Herein, we report a poly(vinyl alcohol)/phytic acid/amino-polyhedral oligomeric silsesquioxane (PVA/PA/NH2-POSS) conductive composite hydrogel prepared via a facile freeze-thaw cycle method. Within this hydrogel, PA acts as a cross-linking agent and ionizes hydrogen ions to endow the material with ionic conductivity, while NH2-POSS acts as a second cross-linking agent by increasing the cross-linking density of the three-dimensional network structure. The effect of the content of NH2-POSS is investigated, and the composite hydrogel with 2 wt % NH2-POSS displays a uniform and dense three-dimensional (3D) network microporous structure, high conductivity of 2.41 S/m, and tensile strength and elongation at break of 361 kPa and 363%, respectively. This hydrogel is biocompatible and has demonstrated the application as a strain sensor monitoring different human movements. The assembled sensor is stretchable, self-recoverable, and highly sensitive with fast response time (220 ms) and excellent sensitivity (GF = 3.44).

Nitroxide‐mediated radical polymerization of methacryloisobutyl POSS and its block copolymers with poly(n‐acryloylmorpholine)

ABSTRACTNitroxide‐mediated radical polymerization (NMP) of the bulky methacryloisobutyl‐polyhedral oligomeric silsesquioxane (POSS‐MA) is successfully achieved after optimizing reaction conditions such as selection of controlling comonomer, comonomer feed molar ratio, and temperature (10 mol % styrene (S) comonomer at 110 °C using the commercially available BlocBuilder as the NMP initiator). The P(POSS‐MA‐co‐S) with a molecular weight of ~8000 g/mol and dispersity Ж1.2 is afforded under the optimized reaction conditions. The chain‐end fidelity is verified by chain extension experiments with N‐acryloyl morpholine (ACM) via NMP that produces well‐defined amphiphilic hybrid P(POSS‐MA‐co‐S)‐b‐P(ACM)x block copolymers, where the subscript “x” represents the degree of polymerization of (ACM) block (182 < x < 695). The size exclusion chromatography (SEC) of the as‐synthesized samples reveals the presence of some dead P(POSS‐MA‐co‐S) chains that could be removed by a simple purification step. Kinetic investigations reveal a first‐order kinetics for the polymerization of ACM using P(POSS‐MA‐co‐S) as the macroinitiator under NMP conditions. The kinetic and SEC data confirms the controlled nature of the NMP of ACM. Being amphiphilic, the formed P(POSS‐MA‐co‐S)‐b‐P(ACM)x block copolymers self‐assembled in aqueous solution as revealed by the fluorescence spectroscopy experiments with pyrene as the probe for determination of the critical micelle concentration and dynamic light scattering studies. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 428–437

Synthesis of a poly(sulfobetaine-co-polyhedral oligomeric silsesquioxane) hybrid monolith via an in-situ ring opening quaternization for use in hydrophilic interaction capillary liquid chromatography.

An in-situ approach is described for synthesis of poly(sulfobetaine-co-polyhedral oligomeric silsesquioxane) [poly(sulfobetaine-co-POSS)] that can be used in a hybrid monolithic column as a hydrophilic liquid chromatography (HILIC) stationary phase. Synthesis involves (a) radical polymerization of octa(propyl methacrylate)-polyhedral oligomeric silsesquioxane (MA-POSS) and organic monomers such as dimethylaminopropyl methacrylate or vinyl imidazole, and (b) in-situ ring-opening quaternization between 1,4-butane sultone and the organic monomers. The sulfobetaine groups are generated in-situ monolith. This obviates the need for synthesis of sulfobetaine monomer previously. The pore size and permeability of the material can be tuned by using a binary porogenic system (polyethyleneglycol 600 and acetonitrile) and via the composition of the polymerization mixture. The optimized hybrid monolith owns its merits to the presence of POSS and sulfobetaine groups with good mechanical stability, the lack of residual silanol groups, and adequate hydrophilicity. The column filled with the monoliths was evaluated as a stationary phase for HILIC. Several kinds of polar compounds (including nucleosides, bases, phenols, aromatic acids and amides) were separated by using mobile phases with high organic solvent fractions in capillary liquid chromatography. Graphical abstractAn in-situ approach is described for synthesis of poly(sulfobetaine-co-polyhedral oligomeric silsesquioxane) hybrid monolithic column for use in hydrophilic liquid chromatography. The optimized monolith owns good mechanical stability, the lack of residual silanol groups and adequate hydrophilicity. Baseline separation of several kinds of polar compounds is achieved on the column. MA-POSS: octa(propyl-methacrylate) polyhedral oligomeric silsesquioxane; DMAEMA: dimethylaminoethyl methacrylate; AIBN: azodiisobutyronitrile. Poly(DMABS-co-POSS): poly(N-(4-sulfobutyl)-N-methacryloxypropyl- N,N-dimethylammonium-betaine-co-polyhedral oligomeric silsesquioxane).

PLLA/POSS Nanofibers Loaded with Multitargeted pANG Composite Nanoparticles for Promotion of Vascularization in Shear Flow

In vitro prevascularization is particularly important for the clinical application of tissue engineering scaffolds that require vascularization. The principal challenge is simulating the dynamic in vivo environment to promote the continuous growth of blood vessels. In this study, two targeting polypeptides are linked to the two ends of an amphiphilic block copolymer, polyethyleneimine-b-poly(lactide-co-3(S)-methyl-morpholine-2,5-dione)-b-polyethyleneimine (PEI-PLMD-PEI), and self-assembled to form positively charged nanoparticles (NPs), which can bind to negatively charged pANG through electrostatic interactions; the polypeptides are finally loaded into PLLA/polyhedral oligomeric silsesquioxane (POSS) porous fibers to prepare untargeted nanofibers (unTFs), targeted porous nanofibers (TFBs), and targeted nanofiber bundles. The effects of the porous nanofibers on human umbilical vein endothelial cell (HUVEC) transfection, spreading, proliferation, morphology, and expression of related factors are investigated under the action of shear flow force. The results show that the PLLA/POSS nanofibers can maintain stable release of multitargeted NPs for nearly 45 days. Both the dual-targeted porous NPs and shear flow improve the pANG transfection efficiency and promote cell proliferation, and they have a good synergistic effect. These results provide a potential strategy for designing HUVEC-specific gene carriers and using shear flow to enhance endothelialization.