Tzong-Ming Wu

Unsaturated polyester resin (UPR) composites containing 0.02–1.00 %wt. ZnO nanoparticles (ZnO NPs) were prepared using an MEKP–cobalt octanoate curing system and evaluated for sanitary sewer components. The influence of ZnO NPs content on chemical structure, hardness, tensile and flexural properties, scratch resistance, thermal behaviour, and surface characteristics was investigated using FTIR, XRD, mechanical testing, TGA, DSC, optical surface analysis, and SEM. Based on the initial screening, composites containing 0.06, 0.75, and 1.00 %wt. of ZnO NPs were selected for detailed characterisation and subsequent 28-day exposure to activated sludge. The effect of ZnO NPs content was not uniform across the investigated properties. Among the comprehensively characterised formulations, 0.06 wt.% ZnO NPs provided the most favourable overall balance, retaining a tensile strength of 41.20 ± 2.08 MPa while increasing Td,5% from 359.6 °C for pristine UPR to 368.4 °C and Tmax from 410.9 to 422.5 °C. No statistically significant mass changes were observed after activated-sludge exposure, indicating good bulk stability. However, surface roughness and heterogeneity increased, with Ra rising from 0.26 to 1.01 µm for the 0.06%_ZnO NPs composite. Overall, this formulation appears the most promising for further development toward sanitary sewer applications.

The high‐sensitivity trimethylamine (TMA) gas sensor at room temperature is prepared using nitrogen doped graphene quantum dot (N‐GQD) coated electrospun yttrium doped tin oxide (Y:SnO ₂ ) fiber and conducting polyaniline (PANI). The XPS spectrum shows that 0.8 wt% Y:SnO ₂ contains a higher content of oxygen vacancies, which might provide more reaction sites for further interaction with the electron. The response value of TMA gas in the concentration ranging between 10 and 60 ppm at room temperature for fabricated PANI/N‐GQD/Y:SnO ₂ sensors is significantly larger than those of PANI and PANI/Y:SnO ₂ sensors. The response difference of PANI/N‐GQD/Y:SnO ₂ sensor is about two times larger than pure PANI sensors. This fabricated TMA gas sensor also displays exceptional long‐time stability, repeatability and selectivity. Based on the above results, the prepared PANI/N‐GQD/Y:SnO ₂ sensor can be applied to detect the TMA concentration for the freshness of fish.

In this work, the effect of various functional groups between the aromatic rings of dianhydrides on the properties of polyimide (PI)/hollow silica (HS) fiber composites is investigated. For this study, four PI/HS fiber composites are synthesized using 2,2‐bis[4‐(4‐aminophenoxy)phenyl] propane (BAPP) diamine and four different chemical structure of dianhydrides, such as 3,3',4,4'‐biphenyltetracarboxylic dianhydride (BPDA), 4,4’‐(oxydiphthalic anhydride) (OPDA), 3,3',4,4'‐benzophenonetetracarboxylic dianhydride (BTDA) and 4,4’‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) as well as HS fiber prepared using the electrospinning and high temperature calcination technique. The experimental results of four PIs indicate that the incorporation of a flexible and unbulky ether group between the aromatic rings of dianhydride monomer into the PI matrix can decrease the thermal stability, tensile strength, and Tg with increasing chain flexibility. The storage modulus of PI/HS fiber composites can be increased about 50%–60% as compared to pure PI matrix. By adding more HS fiber and hexafluoroisopropylidene groups into PI backbone can lower their high‐frequency dielectric constant due to the increasing amount of low dielectric constant air inside HS fiber and fluorine‐containing groups. The dielectric constants are about 2.82 and 2.59 at 22 and 40 GHz for the 5 wt.% 6FDA‐BAPP/HS fiber composites. These phenomena are possibly accredited to the steric hindrance effect caused by the presence of HS fiber and fluorine‐containing groups, which can interrupt the regular chain packing of PI with increasing their free volumes and decreasing dielectric properties.

In this study, three different series of polyimides (PIs) and their composites fabricated using various chemical structure of diamines and functionalized hollow silica fiber (FHSF) were synthesized. The experimental results of three PIs indicate that the addition of fluorine atoms into the pending groups of PI can decrease the glass transition temperature (Tg) with increase in the chain flexibility and this can lower the dielectric constant of PI. The high‐frequency dielectric constants of the composite materials decrease with increase in the loadings of FHSF. These phenomena are possibly accredited to the steric hindrance effect caused by the presence of trifluoromethyl groups of PI polymer chain and FHSF, which can interrupt the PI chain packing and increase their free volumes, resulting in the decrease of Tg and the dielectric properties of PIs. The high‐frequency circuit transmission loss properties of fabricated composite materials measured using the Test Methods Manual IPC‐TM 650 2.5.5.14 are lower than those of pure polymer matrix, recommending that the prepared materials could be selected as interlayer dielectrics for nano‐level electronic.

A new biodegradable poly(1,4-butylene itaconic-co-terephthalate) (PBIT) and their composites with functionalized layered double hydroxides (m-LDH) are synthesized through the one-step transesterification and polycondensation process. Both Fourier transform infrared spectroscopy (FTIR) and complex viscosity experiments of various compositions of PBIT suggest that the C=C double bond and crosslinking density were increased with increasing the content of itaconic acid comonomer units. Experimental results of PBIT/m-LDH composites observed using X-ray diffraction and transmission electron microscopy to characterized the microstructure and morphology reveal that the m-LDH is extremely distributed and exfoliated in PBIT matrix. The storage modulus at -80 °C of PBIT/m-LDH composites were enhanced more than 70% as compared to those of neat PBIT. The FTIR and scanning electron microscopy were used to characterize the photodegradation behavior for PBIT/m-LDH composites. The change of carboxyl group via photodegradation experiment of PBIT/m-LDH composites reveals that the increasing content of IT unit and m-LDH into PBIT can enhance UV protection ability in the composite materials. These performances were possibly due to the superior UV protection ability of the crosslinking and shielding effect of higher IT unit and m-LDH. This study presents a predictable method to improve the mechanical properties and the UV photodegradation behavior of biodegradable polymer by the incorporation of m-LDH.

The cover image by Qing‐Yi Huang shows highly sensitive detection of NH₃ in the concentration of 0.6~2.0 ppm, which can be used as a gas‐sensing material to detect kidney or hepatic disease from human breath. DOI: 10.1002/app.55209 image

In this study, the newly synthesized polyaniline (PANI)/polyethylenimine modified nitrogen doped graphene quantum dot (PN‐GQD)/tungsten oxide (WO₃) ternary composites were used as ammonia (NH₃) gas sensor detected the NH₃ at room temperature. Fourier transform infrared spectrometer, field‐emission scanning electron microscopy, transmission electron microscopy, and x‐ray photoelectron spectroscopy were applied to illustrate the chemical structure and morphology of the fabricated ternary composites. The NH₃ gas‐sensing performances of PANI/PN‐GQD/WO₃ composite sensor were determined in the concentration between 0.6 and 2.0 ppm at room temperature and the response value of the ternary composite sensor with an exposure of 1.0 ppm NH₃ was 19.9, which was much better than those of PANI and PANI/WO₃ sensors. Because their highly sensitive detection of NH₃ ranging from the concentration between 0.6 and 2.0 ppm at room temperature, the PANI/PN‐GQD/WO₃ composite sensor was confirmed to be extremely effective to detect the kidney or hepatic disease from the human breath. This ternary composite sensor with an exposure of 1.0 and 2.0 ppm NH₃ also displayed extraordinary repeatability and selectivity at room temperature. According to these findings, this fabricated PANI/PN‐GQD/WO₃ composite sensor will be an excellent gas‐sensing material to detect the kidney or hepatic disease from the human breath.

The thermoresponsive drug-loaded hydrogels have attracted widespread interest in the field of medical applications due to their ease of delivery to structurally complex tissue defects. However, drug-resistant infections remain a challenge, which has prompted the development of new non-antibiotic hydrogels. To this end, we prepared chitosan-methacrylate (CTSMA)/gelatin (GEL) thermoresponsive hydrogels and added natural phenolic compounds, including tannic acid, gallic acid, and pyrogallol, to improve the efficacy of hydrogels. This hybrid hydrogel imparted initial crosslinking at physiological temperature, followed by photocuring to further provide a mechanically robust structure. Rheological analysis, tensile strength, antibacterial activity against E. coli, S. aureus, P. gingivalis, and S. mutans, and L929 cytotoxicity were evaluated. The experimental results showed that the hybrid hydrogel with CTSMA/GEL ratio of 5/1 and tannic acid additive had a promising gelation temperature of about 37 °C. The presence of phenolic compounds not only significantly (p < 0.05) enhanced cell viability, but also increased the tensile strength of CTSMA/GEL hybrid hydrogels. Moreover, the hydrogel containing tannic acid revealed potent antibacterial efficacy against four microorganisms. It was concluded that the hybrid hydrogel containing tannic acid could be a potential composite material for medical applications.