Tandem osmotic engine based on hydrogel particles with antipolyelectrolyte and polyelectrolyte effect fuelled by both salinity gradient modes

In this study, we propose a new approach to attain energy by salinity gradient engines with pistons based on hydrogels possessing polyelectrolyte and antipolyelectrolyte effects in a tandem arrangement, providing energy in each salinity gradient mode in a repeatable manner. The swelling of hydrogel with a polyelectrolyte effect and shrinking of hydrogel particles possessing an antipoly-electrolyte effect in desalinated water, and subsequent shrinking of hydrogel with polyelectrolyte and swelling of hydrogel antipolyelectrolyte effect in saline water, generate power in both increasing and decreasing salinity modes. To investigate the energy recovery, we scrutinized osmotic engine assemblies by a setup arrangement of pistons with hydrogel particles, with polyelectrolyte and antipolyelectrolyte effects, in tandem. The energy recovery from the tandem engine setup (calculated based on dry form for each polyelectrolyte polyacrylate-based hydrogel-SPA) and antipolyelectrolyte– sulfobetaine-based gel with methacrylate polymeric backbone-SBE) up to 581 J kg−1 and a mean power of 0.16 W kg−1 was obtained by the tandem setup of SPA and SBE hydrogel containing 3% crosslinking density and particle size of 500 microns with an external load of 3.0 kPa. Exchange of sulfobetaine with methacrylamide (SBAm), the main polymer backbone, revealed a positive increase in energy recovery of 670 J kg−1 with a mean power of 0.19 W kg−1 for the tandem system operating under the same parameters (SPA@SBAm). The energy recovery can be controlled, modulated and tuned by selecting both hydrogels with antipolyelectrolyte and polyelectrolyte effects and their performing parameters. This proof of concept provides blue energy harvesting by contributing both polyelectrolyte and antipolyelectrolyte effects in a single tandem setup; together with easy accessibility (diaper-based materials (SPA)) and known antibiofouling, these properties offer a robust alternative for energy harvesting.- Qatar National Research Fund (QNRF) - grant # NPRP13S-0202-200228. - Qatar University grant #IRCC-2020-004

Perfluoroctylsilane grafted Ti3C2X-based hydrogel liquid marble for controlled movement, self-assembly, light-induced release, and water evaporation system

In this study, a stable and highly hydrophobic perfluoroctylsilane grafted Ti3C2X (PFMXene) possessing repeatable and stable photothermal behavior was applied for fabrication of liquid marble (LM) and hydrogel-based LM. PFMXene-based hydrogel LMs demonstrate floating ability and self-assembly on the water's surface. Moreover, controlled non-contact movement of hydrogel marble through the immersed tool in the water surface reached a speed up to 2 cm s−1. The structural character of the hydrogel matrix allows controlled light-induced disintegration of hydrogel liquid marble or application as a water evaporation system.This publication was made possible by NPRP grant # NPRP13S-0123–200153 from the Qatar National Research Fund (a member of Qatar Foundation). The authors acknowledge financial support made possible by Qatar University grant # QUCG-CAM-22/23–504. The findings achieved herein are solely the responsibility of the authors. The authors thank the Center for Advanced Materials, Qatar University, for support with its facilities. XPS analysis was accomplished in the Gas Processing Center, College of Engineering, Qatar University. SEM was accomplished in the Central Laboratories unit, Qatar University.Scopu