Shengru Long

Semiaromatic polyamides containing ether and different numbers of methylene (2–10) units: synthesis and properties

A series of semiaromatic difluorobenzamide monomers was synthesized by the reaction of diamine and 4-fluorobenzoic chloride using a facile interfacial method. These syntheses were conducted to react the monomers with 1,1-bis(4-hydroxyphenyl)-1-phenylethane (BHPPE), so as to prepare semiaromatic polyamides containing ether units by the method of nucleophilic polycondensation. These had excellent thermal properties with glass transition temperatures (Tg) of 134.4–195.6 °C and initial degradation temperatures (Td) of 405–443 °C. The activation energies of degradation were in the range of 180.1–275.9 kJ mol−1. The resultant polymers can be dissolved in strong polar solvents and supply a tough film with a tensile strength of 89–105 MPa. Also, we found that the complex viscosities of these semiaromatic polyamides ranged from 77 to 688 Pa s at 290 °C. They had the appropriate complex viscosities for melt processing. Moreover, they had much wider processing windows than those of traditional semiaromatic polyamides such as poly(hexamethylene terephthalamide) (PA6T). Interestingly, some of the resultant polymers were found to be naturally self-retardant.

Investigation of the synthesis and properties of isophorone and ether units based semi-aromatic polyamides

The difluoro-substituted monomer, N,N′-bis(4-fluorobenzoyl) isophorone diamine (BFID), was prepared via an interfacial reaction from isophorone diamine and 4-fluorobenzoic chloride. It was then reacted with hydroquinone (or resorcinol, 1,1-bis(4-hydroxyphenyl)-1-phenylethane (BHPPE)) to yield a series of semi-aromatic polyamides. For the synthesized semi-aromatic polyamides, differential scanning calorimetry and thermogravimetric analysis confirmed their high glass transition temperatures (Tg), which were between 217 and 239 °C, and good thermal stability with initial degradation temperatures (Td) in the range of 425–430 °C. Tensile test and dynamic mechanical analysis (DMA) results revealed the good mechanical properties of the semi-aromatic polyamides at ambient temperature and even at 200 °C. Rheological characterization displayed complex viscosities at 310 °C for the semi-aromatic polyamide in the range of 990–1350 Pa s, which suggests that they are suitable for melt processing. Better solubility properties for the resultant semi-aromatic polyamides compared to commercial ones were also found. All the results indicated the good processability of the synthesized semi-aromatic polyamides. In addition, they were found to have almost identical optical transmittance (Tran%: 83–85% at 450 nm) as polycarbonate (PC), in the UV-visible region.

Porous electrospun ultrafine fibers via a liquid–liquid phase separation method

This communication reported a new simple method to produce porous ultrafine fibers during electrospinning process. It was named liquid–liquid phase separation method. This method required introducing suitable amount of water into electrospun solution to form similar stable three-phase membrane-forming systems previously. Scanning electron microscopy was employed to evaluate the morphology of porous ultrafine fibers. According to the investigation result, porous ultrafine fibers were prepared by this method. Liquid–liquid phase separation caused by the change of the property of three-phase systems of charged jet that was led by the rapid solvent evaporation during electrospinning process was considered as the key role for the formation of porous structure. This method is very simple and it not only lowers the requirement on the solvents but also does not introduce any new component into the fibers. Therefore, this method provides a new simple way to form porous structure during electrospinning process.

Porous ultrafine fibers via a salt-induced electrospinning method

A salt-induced electrospinning method to produce porous polymer ultrafine fibers was reported in this work. Scanning electron microscopy, energy dispersive spectrometer, and BET surface area measurement were employed to evaluate the morphology, the element distribution, and the surface area of fibers, respectively. According to the investigation result, pores on the fiber were induced by water-soluble salt during electrospinning process in a humid spinning environment. There was no porous structure on the fiber surface when water-insoluble salt was used in a wet electrospinning environment or when water-soluble salt was used in a dry electrospinning environment. Compared with pure fibers, the average surface area of fibers containing salt increased significantly due to the porous structure. The possible mechanism of the porous structure induced by salt was proposed. Water-solubility salt and humid environment were considered as the key roles in the formation of porous structure. This method provided a new way to form porous structure during electrospinning.

Porous Electrospun PES/PEG Ultrafine Fibers for the Removal of Endocrine Disruptors

In this work, porous polyethersulfone (PES)/polyethylene glycol (PEG) ultrafine fibers were prepared via electrospinning technique, and then were used to removing endocrine disrupters from their aqueous solutions. The surface and the internal structures of PES/PEG ultrafine fibers were characterized by scanning electron microscopy (SEM) and the result showed that they were both porous. The porous electrospun PES/PEG ultrafine fibers can remove endocrine disrupters such as biphenyl A (BPA) and biphenyl (BP) effectively. Compared with pure PES ultrafine fibers, PES/PEG ultrafine fibers showed larger adsorption capacity and faster kinetics of uptaking target species. The hydrophilic properties and the porosity of porous PES/PEG ultrafine fibers can be controlled by adding hydrophilic materials such as polyethylene glycol (PEG), which can improve the adsorption properties of porous PES/PEG ultrafine fibers significantly. The results showed that porous electrospun PES/PEG ultrafine fibers had the potential to be used in environmental application and water treatment.

Interfacial micromechanics of carbon fiber-reinforced polyphenylene sulfide composites

Interfacial micromechanical performance of carbon fiber (CF)-reinforced polyphenylene sulfide (PPS) composites was studied by the microbond test, which has been well accepted as the most important micromechanical test for evaluating the interfacial properties between the fiber and matrix. The effect of annealing treatment and atmospheric plasma treatment on the interfacial adhesion and micromechanics of PPS/CF composites was investigated. The results showed that the apparent interfacial shear strength (τapp) value of microcomposites increased from 33.5 ± 4.3 to 43.9 ± 2.3 MPa after annealing. Moreover, plasma-modified CF was characterized by scanning electron microscope and X-ray photoelectron spectroscopy. It was shown that the surface roughness was improved; the O/C atomic ratio was increased from 16.2 to 28.5%. Though hydrogen and covalent bondings were induced at fiber/matrix interface, the τapp values of PPS/CF composites decreased to 36.4 ± 1.0 MPa with atmospheric plasma treatment, due to the remove of the size layer coated on the surface of CF.

Preparation and drug delivery study of electrospun hollow PES ultrafine fibers with a multilayer wall

The focus of this work was the preparation of hollow ultrafine fibers with a multilayer wall via coaxial electrospinning technology in one step and then studied their drug delivery properties. In this paper, by choosing a suitable dilute hydrophilic polymer solution as the core solution, polyethersulfone (PES) hollow ultrafine fibers with two different layers wall (porous structure layer and dense smooth layer) were formed during coaxial electrospinning process in one step. They showed good drug delivery capacity when curcumin was used as the model drug. There were much larger delivery amounts, more stable release rate, and higher utilization rate of PES hollow ultrafine fibers with a multilayer wall to curcumin than that of PES porous ultrafine fibers. Compared with porous ultrafine fibers, hollow ultrafine fibers with two different layers wall were more suitable to be used as drug delivery materials. Besides, between the two hollow ultrafine fibers with two different layers wall mentioned in this paper, there was much better drug delivery capacity for the hollow fibers produced with the core solution of PVA/DMSO. These results showed that PES hollow ultrafine fibers with two different layers wall have the potential to be used as the drug delivery materials.

Synthesis of High Refractive Index Polyamides Containing Thio-ether Units

Two kinds of new aromatic diamine monomer containing thio-amide unit, bis[4-(p-aminothiophenyl)benzoyl]diamine (ATPBA), were synthesized in two steps, which was reacted with 4,4′-(sulphonyl-bis(p-phenylthio)) dibenzoyl chloride (S-DC) to prepare a new polyamide containing high quantity thio-ether unit. The intrinsic viscosity of PASSA was 0.81–0.93dl/g obtained with optimum synthesis conditions. The polymers were found to have excellent thermal performance with glass transition temperature (Tg) of 245.3–265.8°C, initial degradation temperature (Td) of 446.9–441.6°C. They showed improved solubility in polar aprotic solvents. The optical transmittance of the aromatic polyamide (PA-3a and PA-3b) film at 450 nm is higher than 80%. The thio-ether unit provided the PA-3a and PA-3b with a much higher refractive index ranging from 1.699 to 1.701, and low birefringence between 0.006 and 0.007.

Synthesis and Characterization of Novel Polyamide Containing Ferrocene and Thio-Ether Units

Two kinds of new aromatic diamine monomer containing thio-amide unit, bis[4-(p-aminothiophenyl)benzoyl]diamine (ATPBA), were synthesized by two steps, which was reacted with 1,1′-Ferrocenedicarbonyl Chloride (FCDC) to prepare a new polyamide containing ferrocene and thio-ether unit. The polymers were characterized by FT-IR spectrum, 1H-NMR spectrum, X-ray diffraction, element analyzer, DSC, TGA, SEM, AFM and dissolvability experiment and so on. The intrinsic viscosity of FC-PASAA was 0.42–0.58 dl/g obtained with optimum synthesis conditions. The polymers were found to have excellent thermal performance with glass transition temperature (T g ) of 229.9–276.8°C, initial degradation temperature (T d ) of 389.2–391.5°C. They could afford flexible and strong films with tensile strength 66.0–83.9MPa. They showed improved solubility in polar aprotic solvents. They were used to preparing separation membrane successfully.

Effects of polyarylene sulfide sulfone on the mechanical properties of glass fiber cloth-reinforced polyphenylene sulfide composites

In this article, polyphenylene sulfide (PPS)/polyarylene sulfide sulfone (PASS) was melt blended and PPS/PASS/glass fiber cloth (GFC) composite was prepared. Mechanical testing and dynamic mechanical analysis DMAof PPS/PASS blends and PPS/PASS/GFC composites were performed to inspect the effects of PASS on the mechanical properties of the composites. With the presence of PASS, the strength and modulus of the PPS/PASS blends declined to some extent, while the strength and modulus of the PPS/PASS/GFC composites increased. The results indicate that the addition of PASS is beneficial for strengthening the interaction between PPS and GFC. The scanning electron microscopy results of the impact fracture surfaces of composites were also consistent with the data of mechanical properties.