The
main objective of this work was the development and characterization
of sustainable electro-responsive ionic liquid-based cationic copolymers.
For this purpose degradable semi-interpenetrating polymer networks
(s-IPNs) based on starch and on ion-conducting cationic copolymers
of 2-hydroxyethyl methacrylate (HEMA) and 1-butyl-3-vinylimidazolium
chloride (BVImCl), cross-linked with N,N′-methylenebis(acrylamide) (MBA), were synthesized by following
principles of green chemistry. Cross-linked poly(HEMA-co-BVImCl) copolymers were also prepared for comparison. The resulting
cationic hydrogels (copolymer and s-IPNs) were characterized in terms
of their physicochemical, thermomechanical, morphological, and electrochemical
properties, as well as in terms of cell viability and proliferation
against fibroblast cells. Furthermore, the electro-assisted sorption/release
capacity of the prepared hydrogels toward l-tryptophan (used
as a model biomolecule) was also studied at different applied DC voltages
(0, 2, 5, and 100 V). Results demonstrated that the properties of
the synthesized hydrogels can be tuned, depending on their relative
chemical composition, presenting electronic conductivity and ionic
conductivity values in the 0.1 to 5.2 S cm–1 range,
and complex shear modulus in the 0.6 to 6.4 MPa range. The sorption/release
capacity of the s-IPNs after 3 h at 25 °C can also be modulated
between 2.5 and 70% and 4.5 and 40%, depending on the applied DC voltage
and/or sorption/release medium. Finally, none of the synthesized cationic
hydrogels induced fibroblast cells lysis, although s-IPNs had a lower
impact on cell proliferation than poly(HEMA-co-BVImCl)
copolymers, indicating a favorable effect of starch on the biocompatibility
of the synthesized s-IPNs. The designed cationic hydrogels could be
useful for the development of efficient, stable, degradable and cheaper
soft and multiresponsive platforms with potential applications in
bioseparation processes, wastewater treatment systems (e.g., pharmaceutical),
biomedical devices (e.g., sustained delivery of specific charged-biomolecules),
and nonleaching electrochemical devices.
