Multiresponsive Microgels: Toward an Independent Tuning of Swelling and Surface Properties

Abstract

Dual-responsive poly-(N-isopropylacrylamide) (PNIPAM) microgels surface-functionalized with polyethylene glycol (PEG) or poly-2-dimethylaminoethyl methacrylate (PDMAEMA) were developed to enable the swelling behavior and surface properties of the microgels to be tuned independently. The thermo-triggered swelling and pH-triggered surface properties of the microgels were investigated in aqueous suspensions using dynamic light scattering and on substrates using the surface forces apparatus. Grafting polymer chains on the microgel surface did not impede the thermo-triggered swelling behavior of the microgels in suspensions and immobilized on substrates. An unprecedented decoupling of the swelling behavior and surface properties could be obtained. More particularly, the thermo-triggered swelling behavior of the PNIPAM underlying microstructure could be tuned below and above the phase transition temperature with no change in the surface potential and adhesion provided by the surface non-responsive PEG.

Robust, anti-biofouling 2D nanogel films from poly(N-vinyl caprolactam-co-vinylimidazole) polymers

“…In conventional precipitation polymerization methods for preparing nanogels, bis-acrylamide is generally used as a crosslinker in a one-pot process. 37,38 Due to simultaneous initiation and cross-linking, the nanogel obtained by this method has a dense core, rather than being integrally soft. The one-pot method may also sacrifice precision in controlling the number of cross-linking sites and lacks the means to regulate the crosslink length.…”