Stimuli-responsive microgels for the loading and release of functional compounds: Fundamental concepts and applications

Klinger, Daniel; Landfester, Katharina

doi:10.1016/j.polymer.2012.08.053

Cited by 212 publications

(170 citation statements)

References 221 publications

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“…Microgels based on N -isopropylacrylamide (NIPAM) in particular are of great interest, due to its volume phase transition temperature (VPTT) of around 32 • C [1][2][3]. The particles are highly swollen by hydrogen bonds between the solvent and the polymer backbone below this temperature.…”

Section: Introductionmentioning

confidence: 99%

The impact of the cononsolvency effect on poly (N-isopropylacrylamide) based microgels at interfaces

2014

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The paper addresses the effect of solid interfaces on the cononsolvency effect for poly(N -iso propylacrylamide) based microgels containing different contents of the co-monomer allyl acetic acid (AAA). The cononsolvency effect is studied by dynamic light scattering (DLS) in solution and with atomic force microscopy (AFM) at surfaces against different mixtures of water and organic solvent (ethanol, iso-propanol, and tetrahydrofuran). For the studies at interfaces, the microgels are spin coated on silicon wafers that are precoated with poly(allylamine hydrochloride) (PAH). The minimum in particle volume due to cononsolvency shows a pronounced shift from 10-20 % of organic solvent to 40-50 % after deposition at the Si/PAH wafer. The strong shift indicates an increase of water to organic solvent ratio within the gel at the surface with respect to the bulk solution. In order to understand the increase of water to organic solvent ratio, shrinking/reswelling AFM experiments for different spincoating conditions and under ambient conditions are carried out. Spin coating from water instead from different solvent mixtures has no effect on the cononsolvency. In ambient conditions, the cononsolvency effect disappears

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Section: Introductionmentioning

confidence: 99%

The impact of the cononsolvency effect on poly (N-isopropylacrylamide) based microgels at interfaces

2014

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“…Comparison of swelling diagrams on hydrogels with various compositions reveals that the steepness of these curves in the vicinity of the critical temperature T * decreases when the concentrations of monomers and cross-linker grow. Figures 3,4,9,11,and 14 show that adjustable parameters in the constitutive equations evolve consistently with concentrations of monomers C mon and cross-linker C cr (or its equivalents C cr and Z ). Given a concentration of monomers, coefficients a 1 and a 2 in the Landau expansion decrease exponentially with C cr (Figs.…”

Section: Constrained Swellingmentioning

confidence: 90%

“…Given a concentration of monomers, coefficients a 1 and a 2 in the Landau expansion decrease exponentially with C cr (Figs. 3,9,11,14). For a given concentration of cross-linker, these coefficients grow with C mon (Figs.…”

Section: Constrained Swellingmentioning

confidence: 90%

Volume phase transition in thermo-responsive hydrogels: constitutive modeling and structure–property relations

Drozdov

2014

Acta Mech

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A model is developed for the elastic response of a thermo-responsive hydrogel subjected to swelling under an arbitrary deformation with finite strains. The constitutive equations involve the stress-strain relation, the nonlinear diffusion equation for water molecules, the heat conduction equation, and the Allen-Cahn equation for a scalar order parameter (proportional to the concentration of hydrophilic segments in polymer chains). Material constants are found by fitting equilibrium mass uptake diagrams for macro-and microgels under unconstrained and constrained swelling in the vicinity of the volume phase transition temperature. Quantitative agreement is demonstrated between the experimental data and the results of simulation. The effect of composition of hydrogels (concentrations of monomers and cross-linker) on adjustable parameters is analyzed numerically.

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“…Beides kann durch Verwendung sensitiver Polymernetzwerke erreicht werden. [10,11] Zusätzlich zur Kontrolle der Gelsensitivität muss die Grçße und Form der Mikrokapseln kontrolliert werden. Die ursprüngliche Verwendung des Ausdrucks Mikrogel bezog sich auf Partikel mit Abmessungen einiger hundert bis tausend Nanometer bis hinunter zu einzelnen intramolekular vernetzten Polymerknäueln.…”

Section: Mikrogele: Weich Winzig Wichtigunclassified

Klein aber fein: sensitive Mikrogelkapseln

Seiffert

2013

Angewandte Chemie

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Stimuli-responsive microgels for the loading and release of functional compounds: Fundamental concepts and applications

Cited by 212 publications

References 221 publications

The impact of the cononsolvency effect on poly (N-isopropylacrylamide) based microgels at interfaces

The impact of the cononsolvency effect on poly (N-isopropylacrylamide) based microgels at interfaces

Volume phase transition in thermo-responsive hydrogels: constitutive modeling and structure–property relations

Klein aber fein: sensitive Mikrogelkapseln

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