Abstract
Microgels composed of stimuli responsive polymers have attracted worthwhile interest as model colloids for theorethical and experimental studies and for nanotechnological applications. A deep knowledge of their behaviour is fundamental for the design of new materials. Here we report the current understanding of a dual responsive microgel composed of poly(N-isopropylacrylamide) (PNIPAM), a temperature sensitive polymer, and poly(acrylic acid) (PAAc), a pH sensitive polymer, at different temperatures, PAAc contents, concentrations, solvents and pH. The combination of multiple techniques as Dynamic Light Scattering (DLS), Raman spectroscopy, Small Angle Neutron Scattering (SANS), rheology and electrophoretic measurements allow to investigate the hydrodynamic radius behaviour across the typical Volume Phase Transition (VPT), the involved molecular mechanism and the internal particle structure together with the viscoelastic properties and the role of ionic charge in the aggregation phenomena.
Highlights
Polymeric hydrogels are widely used systems for technological and biomedical applications due to their high water content and biocompatibility
We review the behaviour of PNIPAM and IPN microgels as a function of temperature, concentration, poly(acrilic acid) (PAAc) content and pH that has been widely explored by combining different experimental techniques
Temperature and pH responsive microgel composed of interpenetrating polymer networks of PNIPAM and poly(acrylic acid) were synthesized through a free radical polymerization method
Summary
Polymeric hydrogels are widely used systems for technological and biomedical applications due to their high water content and biocompatibility. Among them poly(Nisopropylacrylamide) (PNIPAM) is one of the most studied polymer for stimuli-responsive hydrogels, thanks to its very attracting temperature dependent properties. Individual chains of PNIPAM in aqueous solutions exhibit a coil to globule transition when temperature is increased above a Lower Critical Solution Temperature (LCST ≈ 305 K). In PNIPAM hydrogels, where the polymer chains are crosslinked, a VPT occurs at. In recent years considerable efforts have been made to find multi-stimuli-responsive systems able to enhance properties and ductility of PNIPAM hydrogels. Systems with both temperature and pH sensitivity, such as PNIPAM and poly(acrilic acid) (PAAc), are of great scientific and technological importance, due to their possible use in many biomedical applications [1]. The synthesis methodsSyntax Error: Unknown character collection 'cpsFontConverter-Synthetic-Registry-cpsFontConverter-Synthetic-Order'
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