Abstract
Background: Superporous interconnected cryogel networks are intriguing materials for in situ synthesis conductive polymers. Additionally, the entrapment of conductive graphene within cryogels network further offers additional advantages along with conductive polymers in sensor applications.
Objective: Prepare superporous poly(4-vinyl pyridine) (p(4-VP)) cryogel embedding graphene oxide (GO) and reduce GO to obtain p(4-VP)-rGO cryogel. Then use these p(4-VP)-rGO cryogel composites as template for in situ synthesis of conductive polymers of poly(Aniline) (p(An)), poly(Pyrrole) (p(Py)), and poly(Thiophene) (p(Th)).
Method: P(4-VP) cryogel composites embedding GO were performed at cryogenic conditions via free radical polymerization technique. The reduction of GOs within p(4-VP)-GO cryogel composites were done with the treatments of aqueous solutions of hydrogen iodine (HI), hydrazine (N2H4), vitamin C (Vit-C), polyethyleneimine (PEI), tannic acid (TA), and sodium borohydride (NaBH4). Then, HI reduced p(4-VP)-rGO composite was used for in situ conductive polymers synthesis.
Result: The conductivity of HI reduced p(4-VP)-GO (p(4-VP)-rGO) cryogel composite increased 40x103-fold from 3.3x10-10 to 1.3x10-5 S.cm-1. The conductivities of p(4-VP)-rGO/p(An), p(4-VP)- rGO/p(Py) and p(4-VP)-rGO/p(Th) were calculated as 3.83x10-3, 1.77x10-4, and 4.13x10-5 S.cm-1 with 10x106, 55x104, and 125x103-fold increase in comparison to neat p(4-VP) cryogel conductivity. Upon 30, 60, 120 and 240 min CO2 exposure with 200 mL/min rate at room temperature, the conductivities of p(4-VP)-rGO cryogel composites was decreased 2, 4, 11 and 9-fold, whereas the conductivity of p(4-VP)-rGO/p(An) cryogel composites was also decreased 14, 19, 23, 25-folds.
Conclusion: P(4-VP) based cryogels such as p(4-VP)-GO, p(4-VP)-rGO, and p(4-VP)-rGO/p(An) cryogel composites can be potentially used as sensor for different gaseous including CO2 gas.
Keywords: CO2 sensors, conductivity, cryogel/GO/Conductive polymer, hydrogel/cryogel GO composite, Hydrogel/cryogel sensor, in situ conductive polymer synthesis.
Graphical Abstract
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