The growing popularity of smart electronics in wearables, the Internet of Things (IoT), soft robotics, and biomedical implants simultaneously demands more reliable and durable power sources. However, limitations on battery life continue to compromise reliability, prompting the search for sustainable solutions for flexible, self-powered systems. In this work, stretchable self-powered piezoelectric nanogenerators have been designed from functionalized piezoelectric nanofibers with a bioinspired coiled helical microstructure. Composed of two-dimensional (2D) Ti₃C₂T_x MXene and silver nanoparticles (AgNPs) embedded in a poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) matrix, the coiled structure achieves a mechanoelectrical energy conversion efficiency of 17%, and a power output of 6.6 mW cm⁻³ at 50% strain, twice the performance of similarly coiled structures. These improvements were attributed to the threefold increase in the piezoelectric coefficient through the addition of 1 wt% AgNPs to the P(VDF-TrFE)/MXene (0.1 wt%) and the coiled structure further enhancing β-phase formation reaching up to 70%. An electrospun mat sensor with dimensions of 2 × 3 cm generated 3 V at 1 Hz under an applied pressure of 7 kPa. The coil compact and lightweight design enables seamless integration into miniaturized electronics and wearable biomedical devices, promising a sustainable, battery-free power solution.

The reaction kinetics and structure property relationships of isomeric tri-aromatic ether-linked amines based on the structure bis (aminophenoxy) benzene, cured with diglycidyl ether of bisphenol F (BisF) are investigated in this study. Reaction kinetics are explored using rheological and calorimetric measurements, whereas structure property relationships are determined from their flexural properties, dynamic mechanical properties (DMTA), and thermogravimetric analysis (TGA). A BisF network cured with 4,4 diamino diphenyl sulphone (44 DDS) is used as a benchmark to represent a commercially available high-performance resin system. Varying the substitution of the ether linkages on the aromatic groups from ortho, meta to para was found to have a significant impact on reactivity and network properties after cure. The variations are explained in terms of inductive and resonance effects primarily acting on the outer aromatic rings. Interestingly, however, these same effects acting on the central aromatic ring also impact upon reactivity despite their proximity from the amines. Mechanical and thermal properties are explained by changes in the short-range molecular mobility within the network architecture such as phenylene rotations or π flips and are experimentally validated from the breadth and position of the subambient γ relaxations.

Isomeric tri-aryl ketone amines, 1,3-bis(3-aminobenzoyl)benzene (133 BABB), 1,3-bis(4-aminobenzoyl)benzene (134 BABB), and 1,4-bis(4-aminobenzoyl)benzene (144 BABB) are synthesized and cured with diglycidyl ether of bisphenol A and diglycidyl ether of bisphenol F in this work. Differential scanning calorimetry and near-infrared spectroscopy reveal higher rate constants and enhanced secondary amine conversion with increasing para substitution attributed to resonance effects and the electron withdrawing nature of the carbonyl linkages. Glass transition temperatures increase from 133 BABB to 134 BABB, but decrease modestly for the 144 BABB hardener. With increasing para substitution, the flexural modulus and strength both decrease while the strain to failure increases but all BABB amines displaying higher mechanical properties than the corresponding 4,4-diaminodiphenyl sulfone (44 DDS) networks. The thermal stability of the BABB networks is found to be modestly lower than 44 DDS, but char yields are significantly higher. Changes in thermal and mechanical properties are described in terms of molecular structure and equilibrium packing density.

Tri-aryl ether and ketone amine isomers with varying meta and para aromatic substitution have been cured with a commercially available diglycidyl ether of bisphenol F epoxy resin. The mechanical and thermal properties, as well as reaction rates have been characterised and are related to specific changes in the aryl linkage groups and substitution patterns. In the case of the rate of reaction, inductive and resonance effects, from the strongly electron donating ether groups increase amine reactivity while conversely the electron withdrawing carbonyl groups reduce amine reactivity. With respect to thermal and mechanical properties, comparative molecular mobility within the rigid networks controls the mechanical and thermal properties. The carbonyl group increases Tg, char yield, modulus and strength, whilst reducing displacement at yield. Regardless of chemical linkage, increasing para substitution increased Tg and displacement at failure, whilst reducing strength and stiffness. The insights gained from this work, provide new pathways towards the rational design of a new generation of epoxy amine networks with improved processability, strength, stiffness and ductility.

The reaction kinetics and structure property relationships of isomeric tri-aromatic ether linked amines based on the structure bis (aminophenoxy) benzene cured with diglycidyl ether of bisphenol F (BisF) are investigated in this study. Reaction kinetics are explored using rheological and calorimetric measurements, while structure property relationships are determined from flexural properties, dynamic mechanical properties (DMTA) and thermogravimetric analysis (TGA). The isomers had a varied substitution pattern from ortho, meta to para, and had a significant impact on both amine reactivity and properties after cure. All of the observed changes could be explained in terms of inductive and resonance effects dominated by the outer aromatic rings. The mechanical and thermal properties were understood in terms of the variations in short molecular mobility within the network architecture, more specifically the extent to which phenylene rotations or π flips occur and is experimentally validated from the breadth of the sub-ambient γ relaxations.