Wayne Hayes

Hydrocarbon ionomers have emerged as promising per- and polyfluoroalkyl substance (PFAS)-free alternatives to perfluorosulfonic acid (PFSA) ionomers in proton-exchange membrane fuel cells. This study systematically examines hydrocarbon ionomer performance over a broad range of humidity and temperature conditions to identify the key challenges limiting commercial viability. The first challenge is the low water content per acid group at a given relative humidity, as hydrocarbon ionomers exhibit less swelling on an acid-normalized basis. The second challenge is the complexity of proton conduction pathways; analysis using percolation theory suggests that hydrocarbon ionomers exhibit significantly more complex conduction pathways than PFSA ionomers. The third challenge is proton transport activation energy, as determined by Vogel–Fulcher–Tammann analysis, which shows that hydrocarbon ionomers can achieve activation energies comparable to PFSAs, but only with specific ionomer architectures.

Materials utilized for impact protection must be capable of effective absorption and dissipation of external impact forces as well as being lightweight, flexible, and comfortable. One strategy to meet these stringent criteria is through the exploitation of adaptive dynamic networks. Herein, we report a series of chain-extended supramolecular polyurethane and poly(urethane–urea) elastomers, which utilize both hydrogen bonding interactions and disulfide units to impart structural stability, reprocessability, and reversible adaptability. The key design element of these phase-separated materials is the use of two distinct dynamic bonding mechanisms within the hard domains, which serve to efficiently reinforce the elastomeric assemblies. The optimum elastomer exhibited excellent self-recoverability (91% and 99%) after relaxing for 30 and 60 s, respectively, at 20% compression. During loading–unloading compression cycles, the elastic recovery ratios of this elastomer reached 77 ± 0.3% with dissipated energies of 235,000 J m^–3 at a deformation of 80%. This study highlights how the combination of noncovalent interactions and dynamic covalent bonding can be utilized to generate elastomers capable of rapid autonomous healing and property recovery while simultaneously providing exceptional energy dissipation, paving the way for the impact-resistant systems.

Cross-linked flavone networks have been generated that degrade under tumour-relevant conditions to demonstrate sustained release of the active flavonoid payloads.

Different mixing domains were achieved during extrusion printing with different feed properties.

To address the current needs of the pharmaceutical industry, this study demonstrates how the design of LMWGs can be exploited to tune self-assembled nanostructured gel morphologies to enable the selective crystallisation of polymorphous APIs.

Photoresponsive polymeric hydrogel lattices have been generated using stereolithographic 3D printing to afford objects that can change shape when irradiated with UV-vis light that are capable of exhibiting payload release.

While strong polymeric adhesives are widely valued, their removal can present a significant challenge where substrate recycling is concerned. Recent advancements in “debond-on-demand” adhesives have shown promising enhancements in adhesive strength and debondability. However, they often face a choice between increased adhesive strength or the rate and degree of debonding. Here we report using a rapidly base degradable chain-extender within a series of polyurethanes which possess tailorable adhesive characteristics. These chain-extended polyurethanes (CEPUs) possess high shear strength (8.20 MPa) which upon exposure to base solutions depolymerise (up to 88% loss in M _n) facilitating up to 92% loss in shear strength after only 30 min. Formulation of the CEPUs into inks suitable for continuous inkjet (CIJ) printing produced defined images which upon treatment with base solutions could be removed from the substrate. Having been engineered for circularity, the parent CEPUs can be recycled postdegradation into daughter CEPUs, maintaining their depolymerizable and “debond-on-demand” properties. This work highlights how commercially available starting materials can be utilized to generate highly tailorable polymeric adhesives and inkjet binders capable of rapid depolymerization, ultimately providing an industrially attractive system to increase the recyclability and sustainability of waste materials.

This paper reports the synthesis and study of crosslinked polyurethanes that possess sulfone ethyl urethane chain-extenders which provides base triggered self-immolative degradation properties – notably for use in debond-on-demand processes.

Hydrocarbon ionomers are a fluorine-free alternative to perfluorinated sulfonic acid ionomers. To be viable the conductivity gap between the ionomers must be closed, this analysis explains and explores strategies to achieve this.