Thermoplastic polyaryletherketones (PAEKs) exhibit excellent mechanical properties and fluid stability, but their glass transition temperatures (Tg) are low and their all-aromatic nature makes processing challenging. We will present a synthetic route toward phenylethynyl-functionalized hyperbranched PAEKs (hbPAEKs) (Tg = 151 °C) that can be cross-linked to form flexible films with high Tg's (187-237 °C) and good mechanical properties (E′ = 4 GPa, σ = 44 MPa, and ϵ = 1.76%). After cross-linking, the films are amorphous, easy to handle, and insoluble. We will report on the melt rheology of the hbPAEK precursors, with and without reactive phenylethynyl-reactive functionalities, and the thermomechanical characteristics of thin cross-linked films using dynamic mechanical thermal analysis, differential scanning calorimetry, and tensile testing. We believe that our findings can be extended to other all-aromatic structural and functional polymer architectures that are otherwise impossible to process.

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.

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.

A star-shaped trifunctional acyl chloride bearing ether linkages was synthesized as an alternative to the commonly used trimesoyl chloride (TMC) in the preparation of polyamide thin film composite membranes (TFC). Although this star-shaped acyl chloride has the same functionality as TMC, it is larger in size and its acyl chloride groups are less reactive due to the electron donating ether linkages. In this work, we prepared TFC membranes by the interfacial polymerization of both this star-shaped acyl chloride and TMC with either one of the two structural isomers: m-phenylenediamine (MPD) or p-phenylenediamine (PPD). No strong effect was observed of the substitution pattern of the aromatic diamine on the membrane formation with TMC, due to the high reactivity of the acyl chloride groups of TMC. In contrast, the use of this star-shaped acyl chloride results in significant differences in the properties of the formed TFC membrane depending on the use of MPD or PPD. Where TMC-MPD membranes are well-known for their excellent retention, we could not obtain defect-free membranes prepared from MPD and this star-shaped triacyl chloride (R_rosebengal<77%). The use of PPD instead of MPD, however, did result in defect-free membranes (R_rosebengal>97%) with an acceptable clean water permeance (2.5 L m⁻² h⁻¹ bar⁻¹).

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.