A facile CO₂ switchable nanocomposite with reversible transition from sol to self-healable hydrogel

Abstract

In this paper, we report a CO 2 /N 2 -switchable sol to gel transition system based on a triblock copolymer of dimethylaminoethyl methacrylate (DMAEMA) and ethylene oxide (EO), with a measured composition DMAEMA 6 -EO 109 -DMAEMA 6 , in aqueous nanoclay dispersions. LAPONITE® is exfoliated and stabilized by Pluronic F127. The aqueous mixture exhibits a strong response to CO 2 , changing from a low viscous sol to a self-healable gel. In the presence of CO 2 , the PDMAEMA blocks are protonated and the positive charged triblock copolymer bridge the negative charged nanoclays, formation of a physical network. As a consequence, a sol to gel transition is observed at the macro level. Upon removal of CO 2 through bubbling with N 2 , a corresponding gel to sol transition occurs due to the deconstruction of the physical network, which is a result of the departure of the deprotonated PDMAEMA blocks from the nanoclays.This sol to gel transition is fully reversible. Furthermore, the formed gel possesses excellent self-healing ability, meaning that this hydrogel is capable of autonomous healing upon damage. Thus, we believe the fundamentals of the present CO 2 -responsive smart hydrogel may hold promise for a wide range of areas, such as intelligent delivery systems and smart biomaterial fields, or a potential CO 2 plugging agent for enhanced oil recovery (EOR) performed by CO 2 flooding.

CO2-responsive polymeric materials: synthesis, self-assembly, and functional applications

“…31 For the preparation of the PEO macroinitiator, the ATRP of mono-methoxyl poly(ethylene oxide) was conducted in dichloromethane (CH 2 Cl 2 ) in the presence of triethylamine (TEA) at room temperature for 24 h using 2-bromo-isobutyryl bromide (BiBB) as initiator. 205 A fluorophore-polymer conjugate, PBI-PDMAEMA, comprised of two CO 2 -switchable arms of PDMAEMA and a centre Hybrid nanoparticles consisting of a PDEAEMA shell and fluorescence-labelled magnetic cores were synthesized by a two-step ATRP. 20).…”

“…The CO 2 -switchability investigation showed an optical response of the device to CO 2 . 205 The middle block was poly(ethylene oxide) (PEO) and the two end blocks were PDMAEMA. CO 2 -switchable PDMAEMA-based hydrogels have been used as antidote delivery vehicles.…”

CO2 Responsive Imidazolium‐Type Poly(Ionic Liquid) Gels

“…The produced transparent PIL solution could be gelated upon CO 2 bubbling, and thus a transparent and stable PIL gel was obtained. The formed PIL gels could be converted back to the solution via stirring under an N 2 atmosphere in 5 min (Figure b) . In order to get detailed insights into the nature of the PIL sol/gel system, NMR spectrum analysis was carried out.…”

“…Figure c shows the representative 1 HNMR spectra of the PIL‐BF 4 polymer solution in D 2 O before and after the CO 2 bubbling, and after N 2 bubbling at room temperature. Upon CO 2 bubbling, the resonance peaks of PDMAEMA (e.g., protons of methyl groups linked to the tertiary amine group at 2.8 ppm) display downfield shift, indicating the formation of bicarbonate salts of protonated amine groups …”

“…The formed PIL gels could be converted back to the solution via stirring under an N 2 atmosphere in 5 min (Figure 3 b). [45][46][47] In order to get detailed insights into the nature of the PIL sol/ gel system, NMR spectrum analysis was carried out. Figure 3 c shows the representative 1 HNMR spectra of the PIL-BF 4 polymer solution in D 2 O before and after the CO 2 bubbling, and after N 2 bubbling at room temperature.…”