Core–Shell Microgel-Based Surface Coatings with Linear Thermoresponse

Abstract

We study the swelling and shrinking behavior of core-shell microgels adsorbed on silicon wafers. In these systems, the core is made of cross-linked poly(N-isopropylmethacrylamide) and the shell consists of cross-linked poly(N-n-propylacrylamide). In suspension, these particles exhibit an extended linear swelling behavior in the temperature interval between the lower critical solution temperatures of the two polymers. Using ellipsometry and atomic force microscopy, we show that this linear response is also observed in the adsorbed state.

Determination of Internal Density Profiles of Smart Acrylamide-Based Microgels by Small-Angle Neutron Scattering: A Multishell Reverse Monte Carlo Approach

“…This suggests that the particles in suspension exhibit spherical shape, because anisotropic shapes would result in anisotropic projections. Moreover, we have shown that particles at interfaces and in bulk have a similar swelling behavior, 69 suggesting that internal heterogeneities do not affect measurements on surfaces. In AFM, the particles have a mean radius of 42 nm, and a polydispersity of σ = 20.0 %.…”

Recent advances in stimuli-responsive core-shell microgel particles: synthesis, characterisation, and applications

“…Our approach combined several measurements: at first, a pure p(NIPMAM) core ("core-only"), onto which either deuterated or hydrogenated p(NNPAM) shells have been grown. It is stressed that all cores are the same in our studies [57,59,61,89], i.e. the second synthesis step of the shell has been performed with pre-existing cores, enabling thus direct comparisons.…”

“…In this work, acrylamide-based, thermoresponsive core-shell microgels with a linear phase transition region are exploited as improved carriers for catalytically active silver nanoparticles. The particles are slightly different compared to those described in [57]. The following general microgel structures were used: p(NIPAM-co-AAc)@p(NNPAM), p(NIPMAMc o -A A c ) @ p ( N N PA M ) , a n d p ( N N PA M -c o -AAc)@p(NNPAM).…”

“…Especially the last system shows a drastic change of the reaction rate. Reproduced from reference [68], American Chemical Society ACS Omega swelling behaviour even if confined to a solid interface (Siwafer) [57]. In this work, we have used ellipsometry to measure the film thickness as a function of temperature while the wafers were immersed in water.…”

Resolving the internal morphology of core–shell microgels with super-resolution fluorescence microscopy

“…11 Here, a more complex nanoscale architecture of the microgel particles is investigated: microgel particles based on N-isopropylmethacrylamide (NIP-MAM) (VPTT in water $42 C) 12 are used as seed particles for a second synthesis step, where N-n-propylacrylamide (NNPAM, VPTT of crosslinked homopolymer microgels in water: $22 C) 12,13 is polymerized in the presence of the collapsed seed particles leading to a core-shell structure. 14,15 A peculiar feature of these particles is the linear dependence of the particle size on the temperature. This, especially with the use of the extremely fast responding NNPAM, makes them interesting candidates for sensors or nanoactuators.…”