Graphene oxide-DNA/graphene oxide-PDDA sandwiched membranes with neuromorphic function.

The behavior of polyelectrolytes in confined spaces has direct relevance to the protein mediated ion transport in living organisms. In this paper, we govern lithium chloride transport by the interface provided by polyelectrolytes, polycation, poly(diallyldimethylammonium chloride) (PDDA) and, polyanion, double stranded deoxyribonucleic acid (dsDNA), in confined graphene oxide (GO) membranes. Polyelectrolyte-GO interfaces demonstrate neuromorphic functions that were successfully applied with nanochannel ion interactions contributed, resulting in ion memory effects. Excitatory and inhibitory post-synaptic currents were tuned continuously as the number of pulses applied increased accordingly, increasing decay times. Furthermore, we demonstrated the short-term memory of a trained vs untrained device in computation. On account of its simple and safe production along with its robustness and stability, we anticipate our device to be a low dimensional building block for arrays to embed artificial neural networks in hardware for neuromorphic computing. Additionally, incorporating such devices with sensing and actuating parts for a complete feedback loop produces robotics with its own ability to learn by modifying actuation based on sensing data.

Halide Salt-Catalyzed Crosslinked Polyurethanes for Supercapacitor Gel Electrolyte Applications.

Gel polymer electrolytes are an important advancement in energy storage technology due to their enhanced safety and practical ionic conductivities at ambient temperatures. Herein, a simple one-step facile synthesis of chemically crosslinked polyurethanes containing polyethylene oxide (PEO) and polypropylene oxide (PPO) macromolecular segments was developed, using ubiquitous non-toxic tetrabutylammonium or potassium chloride and bromide salts as catalysts. These salts were shown to catalyze the gelation of diol-diisocyanate polyaddition reactions within minutes. When impregnated with a liquid electrolyte, the resulting gel electrolyte exhibited a practical ionic conductivity of 1.1×10-4  S cm-1 at 40 °C and low segmental chain motion activation energy (11 kJ mol-1 ). These findings further promote PEO-PPO polyurethanes as a biocompatible class of materials suitable for further exploration as gel polymer electrolytes for supercapacitors.

Supramolecular thermogels from branched PCL-containing polyurethanes.

Thermogels are temperature-responsive hydrogels which are most commonly formed by supramolecular self-assembly of polymer amphiphiles comprising of both hydrophobic and hydrophilic segments. Although polyurethane thermogels have shown great promise as biomaterials, their synthesis by step-growth polymerisation of diols and diisocyanates can also result in formation of allophanate branches, which arise from the reaction between free isocyanate groups and urethane linkages along the polymer backbone. In this paper, we investigate the effects of different synthetic conditions on the degree of allophanate branching on polyurethane amphiphiles, and explore the influences of these branches on the polymers' critical micelle concentration (CMC), thermodynamics of micellization and subsequent thermogel properties. Our findings offer new insights into the relationship between polymer structure, micelle and gel properties. These results highlight the importance of taking polymer branching into account for understanding the hierarchical self-assembly of polymer amphiphiles and the resulting thermogel properties and behaviour.