Abstract
Characterization of responsive hydrogels and their enhancement with novel moieties have improved our understanding of functional materials. Hydrogels coupled with inorganic nanoparticles have been sought for novel types of responsive materials, but the efficient routes for the formation and the responsivity of complexed materials remain for further investigation. Here, we report that responsive poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) hydrogel microparticles (microgels) are tunable by varying composition of co-monomer and crosslinker as well as by their complexation with magnetic nanoparticles in aqueous dispersions. Our results show that the hydrodynamic diameter and thermoresponsivity of microgels are closely related with the composition of anionic co-monomer, AAc and crosslinker, N,N′-Methylenebisacrylamide (BIS). As a composition of hydrogels, the higher AAc increases the swelling size of the microgels and the volume phase transition temperature (VPTT), but the higher BIS decreases the size with no apparent effect on the VPTT. When the anionic microgels are complexed with amine-modified magnetic nanoparticles (aMNP) via electrostatic interaction, the microgels decrease in diameter at 25 °C and shift the volume phase transition temperature (VPTT) to a higher temperature. Hysteresis on the thermoresponsive behavior of microgels is also measured to validate the utility of aMNP-microgel complexation. These results suggest a simple, yet valuable route for development of advanced responsive microgels, which hints at the formation of soft nanomaterials enhanced by inorganic nanoparticles.
Highlights
Stimuli-responsive hydrogels, that undergo the volume phase transition in response to external stimuli, have great value in the development of biocompatible smart materials for use in biosensors [1,2,3,4,5], artificial tissues [6], and many other utilities [2,4,7]
We aim to demonstrate that the pNIPAm-co-acrylic acid (AAc) microgels are aptly complexed with magnetic nanoparticles (MNPs), and the hybridized MNP-microgels show the characteristic thermoresponsivity in a repeatable manner
We demonstrate the thermoresponsive behavior of pNIPAm-co-AAc microgels while varying the amount of co-monomer (AAc) and crosslinker (BIS), and further complexation with amine-modified magnetic nanoparticles (aMNP)
Summary
Stimuli-responsive hydrogels, that undergo the volume phase transition in response to external stimuli, have great value in the development of biocompatible smart materials for use in biosensors [1,2,3,4,5], artificial tissues [6], and many other utilities [2,4,7]. The responsivity can be carefully designed to cause the swelling/deswelling of the hydrogels and most common cases are temperature and pH responsive behaviors [8,9,10,11]. (pNIPAm) and acrylic acid (AAc) are widely used due to the lower critical solution temperature (LCST). The LCST, the polymer network is favorable to be collapsed by chain-chain interactions, while above the pKa the network tends to swell due to Coulombic repulsion among the deprotonated acid groups [14,15,16].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
