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The comprehensive balance of the mechanical, interfacial, and environmental requirements of waterborne polyurethane (WPU) has proved challenging, but crucial in the specific application as the binder for high-performance polymer fiber composites. In this work, a multi-step chain extension (MCE) method was demonstrated using three kinds of small extenders and one kind of macro-chain extender (CE) for different chain extension steps. One dihydroxyl blocked small molecular urea (1,3-dimethylolurea, DMU) was applied as one of the CEs and, through the hybrid macrodiol/diamine systems of polyether, polyester, and polysiloxane, the WPU was developed by the step-by-step optimization on each chain extending reaction via the characterization on the H-bonding association, microphase separation, and mechanical properties. The best performance was achieved when the ratio of polyether/polyester was controlled at 6:4, while 2% of DMU and 1% of polysiloxane diamine was incorporated in the third and fourth chain extension steps, respectively. Under the condition, the WPU exhibited not only excellent tensile strength of 30 MPa, elongation of break of about 1300%, and hydrophobicity indicated by the water contact angle of 98°, but also effective interfacial adhesion to para-aramid fabrics. The peeling strength of the joint based on the polysiloxane incorporated WPU after four steps of chain extension was 430% higher than that prepared through only two steps of chain extension. Moreover, about 44% of the peeling strength was sustained after the joint had been boiling for 40 min in water, suggesting the potential application for high-performance fabric composites. [ABSTRACT FROM AUTHOR]

Endothelial cell leakage occurs in several diseases. Intracellular junctions and transcellular fashion are involved. The definite regulatory mechanism is complicated and not fully elucidated. The alpha subunit of the heterotrimeric G-stimulatory protein (Gsα) mediates receptor-stimulated production of cyclic adenosine monophosphate (cAMP). However, the role of Gsα in the endothelial barrier remains unclear. In this study, mice with knockout of endothelial-specific Gsα (GsαECKO) were generated by crossbreeding Gsαflox/flox mice with Cdh5-CreERT2 transgenic mice, induced in adult mice by tamoxifen treatment. GsαECKO mice displayed phenotypes of edema, anemia, hypoproteinemia and hyperlipoproteinemia, which indicates impaired microvascular permeability. Mechanistically, Gsα deficiency reduces the level of endothelial plasmalemma vesicle-associated protein (PLVAP). In addition, overexpression of Gsα increased phosphorylation of cAMP response element-binding protein (CREB) as well as the mRNA and protein levels of PLVAP. CREB could bind to the CRE site of PLVAP promoter and regulate its expression. Thus, Gsα might regulate endothelial permeability via cAMP/CREB-mediated PLVAP expression. [ABSTRACT FROM AUTHOR]

The fast development of Pickering emulsion systems inspires burgeoning demand on the universal synthesis platform for the surface modification of solid particle emulsifiers. In this work, a mild and convenient "visible light–mediated surface grafting through (VSGT)" strategy is proposed. Through the two-step strategy, silica nanoparticles (SNPs) were firstly modified by vinyl alkoxysilane and then used as the substrate for grafting homopolymer brushes via reversible addition-fragmentation chain transfer polymerization under the irradiation of a compact fluorescent lamp (CFL) light source. The whole process was proceeded at room temperature without tedious conditions and complex operations. Importantly, simply by changing the monomer types, hydrophilic acrylic polymer chains can all be grafted on SNP with controlled chain length and relatively uniform high surface densities including poly(acrylic acid) (PAA), poly(N,N-dimethylacrylamide) (PDMA), poly(N-isopropylacrylamide) (PNIPAM), and poly(diacetone acrylamide) (PDAAM). Through the synthesis platform, the interfacial performance of the surface-grafted nanoparticles exhibited as amendable working as Pickering emulsifiers in oil–water system, illustrated by the evolution of interfacial tensions and the inner structures of the corresponding Pickering emulsions. Moreover, the emulsion stabilized by SNP-g-PAA and SNP-g-PNIPAM showed pH and temperature triggered emulsification-demulsification behaviors, respectively, convincing the contribution of the surface grafted polymers and provide a feasible clue for the subtle design on the interfacial texture in advanced Pickering emulsions. [ABSTRACT FROM AUTHOR]

As a kind of smart material, thermoresponsive hydrogels are widely investigated and applied in many fields. Due to the limitation of the freezing temperature of the water, it is a challenge to further broaden their sol–gel transition temperature (Tgel) range, especially below 0 °C. Herein, the lower critical solution temperature type of amphiphilic ABA triblock copolymers, synthesized via two‐step reversible addition‐fragmentation chain transfer (RAFT) polymerization is demonstrated. The hydrophilic A‐block and the hydrophobic B‐block are composed of poly(N,N‐dimethylacrylamide) (PDMAA) and poly(diacetone acrylamide) (PDAAM), respectively. The degree of polymerization (DP) of both A‐block and B‐block shows a significant influence on the Tgel of triblock copolymer dispersion. By changing the length of these two blocks or physically blending these copolymers dispersions, the Tgel can be well adjusted in a temperature range from 45 to −10 °C. Moreover, When the Tgel is higher than 4 °C, the triblock copolymer coatings show a good anti‐fogging property. And when the Tgel is around or lower than the freezing temperature of the water, aqueous dispersions of the triblock copolymer have an ice recrystallization inhibition activity, resulting in the decrease of average maximum grain size (MLGS) of ice crystal. [ABSTRACT FROM AUTHOR]

Latex polymers with precisely designed dynamic mechanical behavior are the key for waterborne damping coatings, which are widely desired in noise and vibration reduction with additional environmental benefits. In this work, we synthesized series of polymer latexes with various crosslinking agents (CA) and network distributions through the control on emulsion polymerization processes. We have revealed that the variation on crosslinking can significantly direct the latex behavior under dynamic conditions as well as its films. The variables involve the CA composition, the functionality, the crosslinking manner, the hydrophilic‐hydrophobic feature as well as the feeding method. Although all the latex films showed the damping peaks locating in the range from −10 to 70°C, their damping behaviors were quite different. Suggested by the empirical parameters of LA and TA, the product from sequential monomer feeding method tended to give good extensional damping performance. Especially when the crosslinking of diacetone acrylamide (DAAM)/adipic dihydrazide was applied, there was a linear increase on LA with the increasing dosage of DAAM from 0 to 10 mmol in the final monomer addition batch. Meanwhile, good constrained layer damping is expected on the products from the power monomer feeding method with the maximum CA dosage shown below 7.5 mmol. The best TA was achieved when the CA of divinylbenzene was used in the dosage of 5 mmol. These results would be valuable to be referenced in the engineering on organic damping materials toward modern industrial and vehicles applications. [ABSTRACT FROM AUTHOR]

Non‐amine‐derived tetrafunctional epoxies have several advantages over the amine‐derived N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenyl methane (TGDDM) in high temperature applications. Although two non‐amine‐derived tetrafunctional epoxies were developed in our laboratory, further improvements in toughness using less loading amount is still desirable. Thus, a tertiary‐amine‐free, non‐planar and triphenylmethane‐containing tetrafunctional epoxy (STFE) with a sulfone spacer was synthesized. When it was mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4′‐diaminodiphenylsulfone (DDS), both thermal and mechanical performances outperformed TGDDM. Moreover, STFE modified system shows the highest toughness (35.7 kJ m–2) among three amine‐free and triphenylmethane‐containing epoxies at merely 5 wt% loading. Molecular simulation and thermomechanical analysis results suggest that the improved mechanical properties could be related to the geometry of the molecule and larger free volume. Despite a marginal drop in Tg, the thermal degradation temperature is better than that of TGDDM/DDS. In addition, the moisture resistance of STFE/DGEBA/DDS is much better than that of TGDDM/DDS. Thus, STFE modified DGEBA could be a potential replacement for TGDDM in some high temperature applications. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

ABSTRACT: Environmentally friendly waterborne polyurethanes (WPUs) modified by moisture‐curable alkoxysilane have been much studied nowadays. In this work, a new diol‐bearing pendant urea‐propyl trimethoxysilane (APD‐Si) was synthesized and used as the chain extender in the preparation of a silicone‐modified WPU dispersion. Both the formation of hybrid networks based on the condensation of trimethoxysilane groups and the enhanced microphase separation of the hard and soft segments have been found to rely on the strong hydrogen‐bonding capability of the urea‐containing spacers, which link the alkoxysilane groups with the backbone of WPU. Because of the synergism of chemically bonded silsesquioxane and physically hydrogen bonded hard domains serving as crosslinking points, the mechanical properties of the hybrid films of WPU are improved, especially the modulus and yield strength. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46628. [ABSTRACT FROM AUTHOR]

ABSTRACT: In some applications, homopolymerized epoxies, which offer better biocompatibility and lower water absorption than amine‐ and anhydride‐cured epoxy, are more preferable; however, using homopolymerized epoxy as matrix in composites still remains a challenge. Herein, homopolymerized bisphenol A diglycidyl ether curing systems with simultaneously improved tensile strength, impact strength, and glass transition temperature (Tg) were achieved by addition of small amounts of tetra‐functional epoxies (TFTEs) with different spacer lengths. Effects of spacer length in TFTE on thermal and mechanical properties were investigated. Results indicated that TFTE with the longest spacer length shows the best mechanical performance. In addition, effects of TFTE loading on thermal and mechanical properties were discussed. Compared with neat bisphenol A diglycidyl ether, addition of 5% tetraglycidyl‐1,10‐bis(triphenylmethane) decane leads to simultaneous improvements in tensile strength, impact strength, and Tg. Effects of thermal cycling on the mechanical properties were also reported. Results suggest that the modified homopolymerized epoxy shows good performances and could be used as matrix materials and possibly in some dental applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46431. [ABSTRACT FROM AUTHOR]

ABSTRACT Fluorinated siloxane-acrylate polymer latex was synthesized via miniemulsion polymerization, which was carried out by pseudo one-step method. In the synthesis protocol, the monomers of octamethylclotetrasiloxane (D4), tetravinyltetramethylcyclotetrasiloxane (D4v), methyl methylacrylate, butyl acrylate, N-methylol acrylamide, and dodecafluoroheptyl methacrylate (DFMA) were first mixed and homogenized into a miniemulsion, which was stabilized by dedecybenzene sulfonic acid. The ring-opening polymerization of cyclosiloxane was then steadily performed under miniemulsion conditions and followed by the postaddition of radical initiators to initiate the polymerization of acrylate and DFMA monomers. The influences on the emulsion properties by acrylic monomer with different addition protocol were investigated in this work. In addition, the synthesized latexes were characterized by using dynamic laser scattering, transmission electron microscope, differential scanning calorimetry, and Fourier transform infrared spectroscopy. These results indicated that the introduction of D4v in the latex can successfully suppress the phase separation between the thermodynamically incompatible components for the formation of uniform hybrid latex particles. The further application of the as-synthesized latex was investigated as a new kind of waterborne textile finishing agent. Moreover, the influences of the content of D4v and DFMA on the finishing properties, especially for the softness, the water repellence, and the antimoisture properties, were systematically studied in this work. With a proper design on the content of the D4v and DFMA, stable textile finishing emulsion was prepared, which can endow the fabric both desirable softness and excellent water resistances. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40161. [ABSTRACT FROM AUTHOR]

A novel epoxidized hyperbranched poly(phenylene oxide) (EHPPO) is designed and synthesized successfully. The structure of EHPPO is characterized by Fourier transform infrared spectra- and quantitative 13C nuclear magnetic resonance spectrum. The synthesized EHPPO is added into diglycidyl ether of bisphenol A as a modifier in different ratios to form hybrids and cured by an anhydride curing agent. Effects of EHPPO addition on the properties of the cured hybrids are investigated. Thermal mechanical analysis results suggest that addition of EHPPO can increase the free volume of the cured hybrid materials. Dynamic mechanical analysis characterizations show that the crosslinking density increases with the increase in EHPPO content. Furthermore, addition of EHPPO results in an improvement in thermal and mechanical properties. The toughening mechanism is also discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Inspired by the growing demand for smart and environmentally friendly polymer materials, we employed 2,2′-disulfanediyldianiline (22DTDA) as a chain extender to synthesize a waterborne polyurethane (WPUR). Due to the ortho-substituted structure of the aromatic disulfide, the urea moieties formed a unique microphase structure in the WPUR, its mechanical strength was enhanced more 180 times relative to that of the material prepared without 22DTDA, and excellent self-healing abilities at body temperature in air or under ultrasound in water were obtained. If the self-healing process was carried out at 37 °C, 50 °C or under ultrasound, the ultimate tensile strength and elongation at break of the healed film could reach 13.8 MPa and 1150%, 15.4 MPa and 1215%, or 16 MPa and 1056%, respectively. Moreover, the WPUR films could be re-healed at the same fracture location over three cutting–healing cycles, and the recovery rates of the tensile strength and elongation at break remained almost constant throughout these cycles. [ABSTRACT FROM AUTHOR]

In this paper, hyperbranched polyether functionalized graphene oxide (EHBPE-GO) was prepared by a facile one-step method. Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), thermogravimetric analyzer (TGA), and trans-mission electron microscopy (TEM) results confirmed the formation of EHBPE-GO. Then, EHBPE-GO was cured with phenolic amides at room temperature to prepare epoxy coatings. The corrosion resistance of epoxy coatings was investigated systematically by using electrochemical and traditional immersion methods. Results show that a small amount of EHBPE-GO (8 wt % of Diglycidyl ether of bisphenol A (DGEBA)) in epoxy coating achieves 50% higher improvement in acid-resistance than unmodified neat DGEBA resin. For the nanocomposite epoxy coating, the superior acid-resistance is attributed to the increased crosslink density and the impermeable 2D structure of EHBPE-GO. This work provides a facile strategy to develop the effective improved corrosion resistance nanofiller for epoxy coating. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • As far as we know, it is the first report on the HP/polymer composites in aqueous dispersion with the HP content as high as 30phr. • The hindered phenol is well dispersed in the polymer matrix without any special post-treatment. • The TA value is improved from 55.6 to 92.3 with 66.2% enhancement as the consequence of HP content at 30 phr. Abstract The building of polymer composite particles in their confined colloidal-scale space is a highlighted topic, leading to advanced structure complexity and high performance in functional coating applications. Here, we demonstrate a direct emulsion polymerization (EP) approach to synthesize composite latex with hindered phenol (HP), a kind of functional small molecules, successfully loaded inside colloidal polymer particles. Monomer conversion as well as the evolution of droplet/particle size has been traced as a function of polymerization time. The results evidence the smooth running of the polymerization process with high HP loading in situ in the aqueous dispersion which could reach 30 phr. As-synthesized HP/polymer latex could be conveniently used for the formation of coating films. The films are unique for the greatly improved damping properties. With HP content of 30 phr, the effective damping temperature range can be broadened to 112 ℃, and the a maximum loss factor can rise to 2.7. The weak hydrogen bonding is found to be the key for the incorporation of HP with the polymer segments, and contributes to the dissipation of vibration energy in the films. Combined with the environmental benefits, waterborne composite latex here is of potential application for the building of green damping coating systems. [ABSTRACT FROM AUTHOR]

Abstract: Core–shell polysilsesquioxane-poly(styrene-butyl acrylate-fluorinated acrylate) [PSQ–P(St-BA-FA)] hybrid latex particles were successfully prepared by seeded emulsion polymerization with polymethacryloxypropylsilsesquioxane (PSQ) synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane (MAPTS) in the presence of emulsifiers as seeds. The chemical composition and core–shell morphology of the resultant hybrid particles were investigated by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM), respectively. TEM and dynamic light scattering (DLS) analysis indicated that the core–shell hybrid particles were uniform and possessed narrow size distributions. The surface properties of the latex films produced from the core–shell hybrid particles were also investigated by contact angle (CA) analysis and X-ray photoelectron spectroscopy (XPS) analysis. The results proved the enrichment of fluorine on the film surface, and the latex films had high contact angles and low surface free energies. Optical measurements indicated that the incorporation of fluorinated acrylate onto PSQ particles can effectively reduce light reflectivity of the obtained transparent hybrid latex film. Atom force microscopy (AFM) characterization showed that the obtained hybrid latex film had a smooth surface. Additionally, thermogravimetric analysis (TGA) indicated that the PSQ–P(St-BA-FA) hybrid latex film had better thermal stability than the poly(styrene-butyl acrylate) [P(St-BA)] latex film. [Copyright &y& Elsevier]

Post-ischemic angiogenesis is a vital pathophysiological process in diseases such as peripheral arterial disease (PAD), heart ischemia, and diabetic retinopathy. The molecular mechanisms of post-ischemic angiogenesis are complicated and not fully elucidated. The G protein stimulatory alpha subunit (Gsα) is essential for hormone-stimulated cyclic adenosine monophosphate (cAMP) production and is an important regulator for many physiological processes. In the present study, we investigated the role of endothelial Gsα in post-ischemic angiogenesis by generating adult mice with endothelial-specific Gsα deficiency (Gsα ECKO ). Gsα ECKO mice had impaired blood flow recovery after hind limb ischemic injury, and reduced neovascularization in allograft transplanted tumors. Mechanically, Gsα could regulate the expression of angiogenic factor with G patch and FHA domains 1 (AGGF1) through cAMP/CREB pathway. AGGF1 plays a key role in angiogenesis and regulates endothelial cell proliferation as well as migration. Knockdown of CREB or mutation of the CRE site on the AGGF1 promoter led to reduced AGGF1 promoter activity. In addition, knockdown of AGGF1 reduced the proangiogenic effect of Gsα in endothelial cells, and overexpression of AGGF1 reversed the impaired angiogenesis in Gsα ECKO mice in vivo . The finding may prove useful in designing new therapeutic targets for treatments of post-ischemic angiogenesis-related diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 He, Lu, Chu, Qin, Gao, Chen, Weinstein, Yang, Zhang, Zhang and Zhang.)

Hypothesis: Intrinsic differences in neurons of the vestibular ganglia result in the increased likelihood of superior vestibular ganglion involvement in vestibular neuritis., Background: Vestibular neuritis is hypothesized to result from herpes simplex type I (HSV1) infection or reactivation in vestibular ganglia. Involvement of the inferior vestibular ganglion is extremely rare in patients with vestibular neuritis., Methods: Primary cultures of rat superior and inferior vestibular ganglion neurons (VGNs) were cultivated separately. Neurons were lytically and latently infected with HSV1 with a US11-green fluorescent protein (GFP) chimera. Percentage lytic infection and baseline reactivation was assessed by microscopy for GFP fluorescence. Trichostatin-A (TSA) was used to stimulate HSV1 reactivation. Virion production was assessed by viral titers. Relative numbers of latency-associated (LAT) transcripts were determined by real-time reverse-transcription polymerase chain reaction (real-time RT-PCR)., Results: Lytic infection rates were equivalent between the two ganglia (p > 0.05). Lytic infections yielded similar amounts of plaque-forming units (p > 0.05). Relative amounts of LAT transcripts did not differ between latently infected superior and inferior VGNs. Latently infected cultures showed no differences in rates of baseline and TSA-induced HSV1 reactivation (p > 0.05). Production of virions was not significantly different between reactivated, latently infected superior versus inferior VGNs (p = 0.45)., Conclusion: Differences in prevalence of superior and inferior vestibular neuritis do not result from intrinsic differences in HSV1 infection or virion production of these neurons. Other factors, such as the length and width of the bony canal containing the ganglia and nerves, account for the greater involvement of the superior vestibular ganglion in vestibular neuritis.

Through a novel method, we successfully synthesized electromagnetic (EM) functional polystyrene@polypyrrole@nickel (PS@PPy@Ni) composite microspheres. The PS@PPy spheres with well-defined core/shell structure have been synthesized via an in situ chemical oxidative copolymerization of pyrrole (Py) and N-2-carboxyethylpyrrole (PyCOOH) templated by PS microspheres. The reaction was carried out under heterophase conditions using the mixture of ethanol and water as the continuous phase. Tailored by the carboxyl groups on the surface of microspheres, magnetic nickel layer has been steady deposited onto the P(Py-PyCOOH) layer of the microspheres through an activation-electroless plating technology. The fine PS@P(Py-PyCOOH)@Ni core/shell structures could be obtained with the PyCOOH content up to 50 wt % in the P(Py-PyCOOH) layer. Moreover, the as-prepared PS@P(Py-PyCOOH)@Ni composites are ferromagnetic materials and behave as a good electromagnetic (EM) absorption material due to the coating of Ni layer around the PS@P(Py-PyCOOH) spheres. The PS@P(Py-PyCOOH)@Ni composite spheres show the remarkable EM wave absorption property with the maximum reflection loss (around -20.06 dB) at 10.69 GHz. The EM wave absorption can retained lower than -10 dB within a broad frequency range from 9.16 to 13.75 GHz.