Mengzhu Liu

Aluminium borate whiskers grafted with boric acid containing poly(ether ether ketone) as a reinforcing agent for the preparation of poly(ether ether ketone) composites

A new soluble boron-containing poly(ether ether ketone) (B-PEEK) was synthesized through iridium-catalyzed C–H borylation of soluble meta-poly(ether ether ketone) and grafted on the surface of aluminum borate whiskers as the coupling agent between the whiskers and poly(ether ether ketone) (PEEK) matrix. The grafted aluminum borate whisker (g-W) reinforced PEEK composites were then prepared via a melt blending method. The coupling effect of B-PEEK was investigated by the interface micromorphology analysis and performance evaluation of PEEK composites. After grafting treatment with B-PEEK, aluminum borate whiskers were found to be dispersed evenly in the PEEK matrix without apparent aggregation. Ascribed to the strong interaction between whisker grafted chains and the PEEK matrix, g-W/PEEK composites show better mechanical properties and izod impact strength, higher crystallization temperature and crystalline fraction (χc) than those composites without grafting modification, indicating B-PEEK is an effective coupling reagent for PEEK and aluminum borate whiskers.

Electrospun carboxylic-functionalized poly(arylene ether ketone) ultrafine fibers optimization, characterization, and water absorption behavior

As a high-performance polymer, carboxylic-functionalized poly(arylene ether ketone)s (PCA-PAEK) was electrospun into ultrafine fibers and characterized. To optimize the process, a set of experiments were designed. As a result, the optimum condition was obtained and the polymer concentration was determined as the most important factor. Incidentally, the PCA-PAEK fibers were found to exhibit superabsorbent behavior. In order to investigate processing characteristics, PCA-PAEK fibers fabricated from different solution concentrations were employed and characterized. The results showed that porosity and changes in water contact angle and water absorbency decreased with an increase in concentration. In addition to a high water absorption capacity, the fibers exhibited good water retention and repeated water absorbency as well. The study on kinetics of water absorption and swelling behavior showed that the mechanism was dependent on the polymer concentration from which the fibers were electrospun. Moreover, both dry and wet PCA-PAEK fibers showed high mechanical properties. Due to these properties, the PCA-PAEK ultrafine fibers are potentially useful as a water-absorbent material.

High-effective preparation of ultrafine poly-(l-lactide-co-∊-caprolactone-diOH) fibers containing silver nanoparticles

A novel method utilizing combination of N, N-dimethylformamide (DMF) and ultraviolet (UV) irradiation to reduce silver (Ag+) ions in situ in ultrafine poly-(l-lactide-co-∊-caprolactone-diOH) (PCLA) fibers was developed. Compared with traditional solvent reduction method, the new method exhibited much higher efficiency. UV–visible spectra indicated that the addition of UV irradiation could shorten the reaction time dramatically. Transmission electron microscope and x-ray photoelectron spectroscopy results demonstrated that the new method had produced a larger number of uniform Ag nanoparticles (AgNPs). After statistical analysis, their mean size was determined as 6.96 nm, which was smaller than that of traditional AgNPs. In addition, as a biodegradable polymer, PCLA was first used to carry AgNPs. It was found that PCLA can be a stabilizing agent of Ag+ ions. Therefore, the formation mechanism of AgNPs with larger number and smaller size can be determined.

Synthesis and properties of a novel poly(aryl ether sulfone) functionalized with pinacol phenylboronate pendants

A novel poly(arylene ether sulfone) (PAES) with pinacol phenylboronate pendants (PAES-B) was prepared by the borylation of brominated PAES (PAES-Br). The reaction was carried out under mild conditions in the presence of cuprous iodide and tri-n-butylphosphine in tetrahydrofuran solution. After heat treatment at 150°C for 132 h, the PAES-B exhibited an interesting solvent resistance. Fourier transform infrared spectroscopy (FTIR) and thermal analysis were performed to investigate the reason. FTIR spectra showed that heat treatment could facilitate losing of pinacol groups and formation of phenylboronic acid in the polymer. Meanwhile, differential scanning calorimetric (DSC) curves demonstrated that the polymer had cross-linking behaviors during heat treatment. In addition, the thermal oxidative stability of PAES-B was researched by the thermogravimetric analysis (TGA).

The mechanical and frictional properties of poly(ether ether ketone) composites with modified aluminum borate whiskers

Poly(ether ether ketone)s (PEEKs) are increasingly used in tribological application. Reinforcing materials such as aluminum borate whiskers are often incorporated into polymeric materials to improve mechanical properties. In this work, aluminum borate whiskers were modified by the boron-containing poly(ether ether ketone)s (B-PEEKs). The modified aluminum borate whiskers (g-W)-reinforced PEEK composites were then prepared via melt-blending method. B-PEEKs showed the good coupling effect by the interface micromorphology analysis and performance evaluation of PEEK composites. After grafting treatment with B-PEEKs, aluminum borate whiskers were found to be dispersed evenly in PEEKs matrix without apparent aggregation. Ascribed to the strong interaction between whisker-grafted chains and PEEKs matrix, g-W/PEEK composites show better mechanical properties, lower friction coefficient, and wear ratio than those composites without grafting modification, indicating that the grafted aluminum borate whiskers (g-W)-reinforced PEEK composites may become a wear-resistant material.