Alexandru Tudor

Poly(Ionic Liquid) Semi-Interpenetrating Network Multi-Responsive Hydrogels.

Herein we describe poly(ionic liquid) hydrogel actuators that are capable of responding to multiple stimuli, namely temperature, ionic strength and white light irradiation. Using two starting materials, a crosslinked poly ionic liquid (PIL) and a linear poly(N-isopropylacrylamide-co-spiropyran-co-acrylic acid), several semi-interpenetrating (sIPN) hydrogels were synthesised. The dimensions of hydrogels discs were measured before and after applying the stimuli, to quantify their response. Samples composed of 100% crosslinked PIL alone showed an average area reduction value of ~53% when the temperature was raised from 20 °C to 70 °C, ~24% when immersed in 1% w/w NaF salt solution and no observable photo-response. In comparison, sIPNs containing 300% w/w linear polymer showed an average area reduction of ~45% when the temperature was raised from 20 °C to 70 °C, ~36% when immersed in 1% NaF w/w salt solution and ~10% after 30 min exposure to white light irradiation, respectively. Moreover, by varying the content of the linear component, fine-control over the photo-, thermo- and salt response, swelling-deswelling rate and mechanical properties of the resulting sIPN was achieved.

CHAPTER 9:Applications of Ionic Liquid Materials in Microfluidic Devices

“Lab-on-a-chip” (LOC) and microfluidics enable the manipulation of fluids at small length scales (from micrometers to millimeters). These systems often have well-defined fabrication processes and are capable of integrating multiple functional elements, to provide complete sample-in/answer-out systems. Nevertheless, the development of fully integrated microfluidic devices still faces some considerable obstacles, including fluidic control, miniaturisation and high costs. Due to their unique properties, ionic liquids have arisen as smart solutions to circumvent some of the hurdles facing current LOC technologies. They can directly benefit microfluidic devices by aiding miniaturised fabrication and passive microfluidic elements for fluid control, sensing and sample storage. Improved chemical reactions and separation, in addition to power generation, temperature control, and electrowetting show potential for reducing manufacturing costs and widening market possibilities. In this chapter we will review and discuss the fundamental applications of ionic liquids within microfluidic systems.