Polymers dynamics of the nonfluoro,nano-brush repelling agent with self-stratifying property in water-based coatings

While perfluoroalkyl acids (PFAAs), also known as C8s, are used extensively in textile repellent coatings, concerns have arisen for their carcinogenicity and hazardous effects on the environment. In this study, a novel water-based, nonfluoro, and nanobrush textile repelling agent was prepared by conventional sol–gel chemistry using amorphous fumed silica and n-octyltriethoxysilane as the starting materials. Minimal interaction between the designed repelling agent and marketed water-based resins was confirmed using linear viscosity region (LVR) analysis and asymmetric-flow field-flow fractionation (AF4), suggesting the self-stratification potential of the repelling agent. More specifically, the repelling agent exhibited excellent compatibility and self-stratifying ability with a force-emulsified acrylic-based resin, affording a water contact angle of 104.3° when incorporated at 7% solid content. Performance tests carried out on thermoplastic polyurethane (TPU) revealed excellent adhesion (100/100) of a final formulation, and a significant increase in water contact angle from 80.1° to 103.8° after treatment. In addition, the fouling area after the removal of a submerged sample from a mixture of slurry, polymer, and oil decreased from 48 to 1% when the repelling agent was added. Moreover, the sludge-fouling property remained unchanged after 1000 cycles of abrasion. These findings demonstrate the potential of the described nonfluoro, nanobrush repelling agent as an environmentally safe alternative for use with commercial resins, in turn realizing a fully water-based hydrophobic coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48003.     

1,4-Butanediol diglycidyl ether-cross-linked hyaluronan inhibits fibrosis in rat primary tenocytes by down-regulating autophagy modulation

Epidural fibrosis, an inevitable part of the postoperative healing process, is one of the important causes of failed back surgery syndrome after spinal surgery. The aim of this study was to examine the inhibitory effect of a novel material 1,4-butanediol diglycidyl ether-cross-linked hyaluronan (cHA) on fibrosis in primary tenocytes. cHA inhibited migration, cell proliferation, and suppressed the expression of fibronectin, but not transforming growth factor-β, in primary tenocytes. cHA significantly increased matrix metalloproteinase-3 but decreased collagen-1 and microtubule-associated protein light chain 3-II expression in a dose-dependent manner compared with control groups. We therefore concluded that suppressing autophagy activity may be involved in the anti-fibrotic effect of cHA in primary tenocytes. Further, cHA may have the potential for preventing epidural fibrosis and subsequent failed back syndrome in patients with laminectomy in the future.     

The Properties of Sintered Calcium Phosphate with [Ca]/[P] = 1.50

In order to obtain the properties of the sintered as-dried calcium phosphate with [Ca]/[P] = 1.50, the characteristics of sintered pellets have been investigated using X-ray diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS), Fourier-transform infrared (FT-IR) spectra, Vickers hardness indentation and scanning electron microscopy (SEM). When the pellet samples were sintered between 700 °C and 1200 °C for 4 h, the hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HA) still maintained the major phase, accompanied with the rhenanite (NaCaPO₄) as the secondary phase and β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) as the minor phases. In addition, the HA partially transformed to α-tricalcium phosphate (α-Ca₃(PO₄)₂, α-TCP) and tetracalcium phosphate (Ca₄(PO4)₂O, TTCP), when the pellet samples were sintered at 1300 °C and 1400 °C, respectively, for 4 h. The maximum density and Vickers Hardness (HV) of sintered pellet samples were 2.85 g/cm³ (90.18% theoretical density (T.D.)) and 407, which appeared at 1200 °C and 900 °C, respectively.     

Influence of manganese substitution into the A-site of perovskite type Ca1−xMnxTiO3 ceramic

Ca_1−xMn_xTiO₃ (x = 0–1.0) perovskite ceramics were prepared by conventional solid state reaction. XRD was used to confirm the microcrystalline nature of the Ca_1−xMn_xTiO₃ crystals. For the x = 0 composition, the XRD patterns were those of a single orthorhombic perovskite while for x = 0.2–0.8, the XRD spectra were those of two orthorhombic perovskite phases: CaTiO₃ and MnTiO₃. For x = 1, XRD pattern was that of the MnTiO₃ phase only. The morphology and particle size of the grains of the different composition were observed using SEM. The size of the particles increased from 0.2 μm to 2–3 μm as x increased from 0 to 0.6. The room temperature dielectric constant at the frequency of 110 kHz for the x = 0.2 and x = 1.0 ceramics were ∼3.41 × 10⁴ and ∼4.99 × 10³, respectively. The ESR linewidth of samples increased with increasing manganese content due to the formation of magnetic cluster. Our ESR studies indicate that the manganese ions are in the Mn⁴⁺ state.     

In vitro study of the SBF and osteoblast-like cells on hydroxyapatite/chitosan–silica nanocomposite

Hydroxyapatite/chitosan–silica (HApCSi) nanocomposites were synthesized by co-precipitated method and their potential application as filler materials for bone regeneration were investigated in simulated body fluid (SBF). To study their biocompatibility, they were cultured with rat osteoblast-like UMR-106 cells for 3, 7, 14, and 21 days. Studies of the silica contents in chitosan matrix showed the presence of silinol (Si–OH) groups in CSi hybrid and their decrease after being composited with calcium phosphate (CaP) which is desirable for the formation of the apatite. XRD and TEM studies showed that the HAp formed in the CSi matrix were nanometer (20–40 nm) in size. Nanocomposites of HApCSi20 processed with 20%v/v silica whisker showed a micro hardness of 84.7 ± 3.3 MPa. Mineralization study in SBF showed the formation of apatite crystals on the HApCSi surface after being incubated for 7 days. In vitro biocompatibility, cell morphology, proliferation, and cell adhesion tests confirmed the osteoblast attachment and growth on the HApCSi20 surface. The density of cells and the production of calcium nodules on the substrate were seen to increase with increasing cultured time. The mechanical evaluation and in vitro experiment suggested that the use of HApCSi composite will lead to the formation of new apatite particles and thus be a potential implant material.     

Thermo- and pH-Responsive Polymersomes of Poly(α,β-N-substituted-DL-aspartamide)s

Materials that can respond to multiple stimuli, such as temperature and pH changes, are of considerable interest for applications in drug delivery systems. Notably, α,β-[poly(2-hydroxyethyl)-DL -aspartamide] is a potentially useful material for such applications. This study investigated the temperature and pH responsiveness of polymers structurally similar to α,β-[poly(2-hydroxyethyl)-DL -aspartamide], namely, poly(α,β-N-substituted-DL -aspartamide)s, in aqueous media. These polymers were derived from polysuccinimide (PSI), which was first synthesized via acid-catalyzed bulk polycondensation of L -aspartic acid (L-ASP) in the presence of 85% o-phosphoric acid under N2. Two primary amino alcohols, 4-aminobutanol (4AB) and 6-aminohexanol (6AH), were then respectively utilized to modify PSI to form poly (α,β-N-substituted-DL -aspartamide)s via aminolysis. Different ratios of these two amino alcohols were used to modify the polymer to produce a series of copolymers with lower critical solution temperatures ranging from 53–28°C when dispersed in aqueous media. Moreover, the properties of the poly(α,β-N- substituted-DL -aspartamide)s in aqueous solution were affected by pH changes. The morphology of the particles formed by these amphiphilic polymers was observed using scanning electronic microscopy and transmission electronic microscopy, and the particles were found to be polymersomes with shell and hollow core structures and diameters of 0.5–1 μm. Other properties of this series of self-assembly copolymers were also characterized. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Solid Film Deposition and Non-Sacrificial Boundary Lubrication

This paper reports the results of studying various approaches in non-sacrificial boundary lubrication in which the deposition of a beneficial surface layer is the result of a chemical reaction involving one or more components in the lubricating fluid but not the metal surface itself. This is in contrast to the conventional approach which involves the rubbing surfaces as reactants with the components in the lubricant and usually promotes wear as the result of chemical change of the surfaces. The most interesting findings show that a reaction between a molybdenum complex and a mixture of zinc dialkylphosphorodithioates produced in situ deposition of MoS₂ and some other unidentified crystalline material. Effective reductions in friction and wear were obtained. Electron diffraction patterns of the worn metal surface established the presence of MoS₂.     

Model interpretation of electrochemical impedance spectroscopy and polarization behavior of H2/CO mixture oxidation in polymer electrolyte fuel cells

A mathematical model is proposed based on electrode kinetics analysis for the oxidation of 2% CO+H₂ mixture in polymer electrolyte fuel cells. Successful simulation of the polarization curve and experimental impedance spectra for Pt/C electrode system confirm the validity of the model which shows that the impedance is strongly dependent on electrode potential. With the increase of potential, an inductive behavior will occur. It is believed that the appearance of this inductive pattern can be used as a criterion for the onset of CO oxidation by the coincidence of the potential at which inductive behavior occurs with the ignition potential for CO oxidation. The effects of change of CO oxidation rate constant and CO adsorption equilibrium constant on impedance pattern, as well as on CO surface coverage and Faradaic current are also delineated with the use of the proposed model.     

Design and Analysis of a Permanent Magnet Spherical Actuator

This paper has proposed a 3-DOF spherical actuator consisting of a ball-shaped rotor with a full circle of permanent- magnet (PM) poles and a spherical-shell-like stator with two layers of circumferential air-core coils. One key feature of this design is the parametrization of PM and coil poles. Based on the torque model of the PM spherical actuator, the relationship between poles' parameters and torque output can be demonstrated. As a result, the actuator design aiming at achieving maximum torque output can be carried out from the relationships. Another advantage of this spherical actuator is its singularity-free workspace, which is verified with the actuator torque model and condition numbers.