Qasim Zia

Similarly to the developments in green electronics, the emerging field of additive piezo-electronics increasingly focuses on more sustainable electroactive materials and cleaner production workflows. However, solution processing with hazardous solvents remains common, even for hybrid organic-inorganic piezoelectric materials (piezocomposites) made from eco-friendly biopolyesters polyhydroxyalkanoates, including ductile copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)(PHBHHx). Therefore, we investigated the solvent-free extrusion-based manufacturing and fused filament fabrication (FFF) of lead-free piezoceramic-rich PHBHHx composite with 80 wt% of barium titanate (BTO). Physicochemical characterization of filaments and prints revealed favorable melt reprocessing capability of PHBHHx as both neat and BTO-rich biopolymers retained chemical structure and thermal stability after three remelting cycles (single or double extrusion at 130 °C–140 °C and FFF at 170 °C). The re-extrusion and FFF processes were calibrated to ensure consistent printability of well-homogenized and well-fused piezocomposite (0–3 connectivity). The tensile loading of neat and BTO-rich PHBHHx structures at increasing speeds revealed complex material behavior of strain-rate-dependent strengthening, weakening, hardening and softening. Despite the high BTO fraction, the composite maintained acceptable flexibility, although the tensile strength decreased due to weaker filler-matrix interfacial bonding. The piezoelectric response and stabilization ( d ₃₃ decay due to initial ferroelectric depolarization) were analyzed over a wide range of poling fields and durations. The 3D-printed piezocomposite demonstrated excellent high-field poling capability up to ∼22 kV mm ⁻¹ . It provided a comparatively high maximum piezoresponse of ∼11 pC/N, matching the predictions of the Jayasundere–Smith model for two-phase particulate composites. The presented sustainable and scalable melt-based workflow is accessible to the 3D printing community, supporting democratization and further advances in the material extrusion additive manufacturing of piezoelectric sensors, energy harvesters/nanogenerators and other devices. The experimental findings are useful for the development of environmentally safe melt processing routes to produce highly filled PHBHHx-based composites.

Metal halide perovskites (MHPs) are thought to be among the most promising materials for smart electronic textiles because of their unique optical and electrical characteristics. Recently, wearable perovskite devices have been developed that combine the excellent properties of perovskite with those of textiles, such as flexibility, light weight, and facile processability. In this review, advancements in wearable perovskite devices (e.g., solar cells, photodetectors, and light-emitting diodes) concerning their device architectures, working mechanisms, and fabrication techniques have been discussed. This study also highlights the technical benefits of integrating MHPs into wearable devices. Moreover, the application challenges faced by wearable perovskite optoelectronic devices—from single devices to roll-to-roll manufacturing, stability and storage, and biosafety—are briefly discussed. Finally, future perspectives on using perovskites for other wearable optoelectronic devices are stated.

Recent progress in doping of halide perovskite materials (HPM) by using targeted elements has provided a dimension beyond structural and compositional modification, for achieving desired properties and resulting device performance. Herein doping of alkali metal ions (Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺) in three-dimensional HPM is reviewed to lay a particular focus on advances in synthesis, doping-induced changes in optical and electrical properties, and their optoelectronic applications. The introduction of alkali metals in HPM shows an effective route for improved morphology, suppressed ion migration, reduction in non-radiative recombination, passivation of bulk and interface defects, and increased thermal stability. In the end, we provide our perspective that the effect of alkali metal incorporation on the efficiency and stability of HPM should be further investigated via in-situ characterization methods and doped HPM should be considered for more functional applications. Graphical abstract

A two-step strategy has been developed to introduce silica nanoparticles into highly porous poly(l-lactic acid) (PLLA) nanofibers. Silica nanoparticles (SiNPs) were firstly synthesized and then modified to be hydrophobic. After PLLA/SiNPs composite fibrous membranes were electrospun and collected, they were re-crystallized by acetone at room temperature for a few minutes. With the re-arrangement of PLLA chains, the nano-/micro-electrospun fibres were transformed from non-porous ones to be porous ones with high surface area. Consequently, SiNPs that were completely covered by PLLA before acetone treatment showed up at the fibre surface. Higher PLLA crystallization also enhanced the Young’s modulus and tensile strength (420 and 8.47 MPa) of the composite membrane. However, incorporation of SiNPs into porous PLLA membranes reduced their modulus and tensile strength (280.66 and 5.92 MPa), but an increase in strain to fracture (80.82%) was observed. Scanning electron microscopy (SEM), focused ion beam SEM, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction were applied to confirm the presence of SiNP in PLLA fibres. The presence of SiNPs inside and outside fibres enhances the hydrophobicity of PLLA/SiNPs nano-fibrous membrane as the water contact angle is greater than 150°. The oil absorption of these porous composite membranes was also tested using four different oils, which can reach the highest absorption capacity when the weight ratio of PLLA and SiNPs is 1:1. The flux of prepared membranes was investigated, and results indicated that SiNPs-loaded membrane effectively enhanced the flux (5200 Lm⁻² h⁻¹).

Ultrafine particulate aerosols less than 100 nm diffuse randomly in the air and are hazardous to the environment and human health. However, no technical standards nor commercial products apply for filtering particle sizes under 100 nm yet. Here we report the development of a porous poly(L-lactic acid) (PLLA) nano-fibrous membrane filter with an ultra-high specific surface area via electrospinning and a post-treatment process. After PLLA fibres were electrospun and collected, they were treated by acetone to generate a blossoming porous structure throughout each individual fibre. Characterizations of morphology, crystallinity, mechanical and thermal properties demonstrated that the porous structure can be attributed to the non-solvent induced spinodal phase separation during electrospinning and solvent induced recrystallization during post treatment. The blossoming porous structure with a high specific surface area contributed to excellent filtration efficiency (99.99%) for sodium chloride (NaCl) ultrafine aerosol particles (30-100 nm) with a low pressure drop (110-230 Pa). Notably, under 7.8 cm/s air flow rate, the membrane samples performed better for filtering smaller-sized aerosol particles than the larger ones when evaluated by the quality factor (0.07). Finally, this finding demonstrates that the electrospun membrane with hierarchical pore structure and high specific surface area hold great potential in applications as air filtering materials.

The aim of this study was to develop statistical models for the effect of binder concentration and curing temperature and time on the air permeability, tear strength, tensile strength, and crocking fastness of pigment‐printed nonwoven polypropylene fabric. The design and analysis of the experimental work were carried out using Minitab^® statistical software according to the Box–Behnken design of response surface methodology. Models were successfully developed. It was found that binder concentration improves the wet crocking and tensile strength while having a negative impact on all other responses. Increase in curing temperature and time affects the fabric tear strength negatively but has a positive effect on wet crocking fastness and fabric tensile strength. It could be concluded that pigment prints of good dry crocking fastness may be obtained on polypropylene nonwovens without deterioration in the mechanical strength and air permeability to a commercially unacceptable level. However, further work is required to improve the wet crocking fastness properties.