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Grafting Density-Dependent Phase Transition Mechanism of Thermoresponsive Poly (glycidyl ether) Brushes: A Comprehensive QCM-D Study

Alexander Schweigerdt, Silke Heinen, Daniel D Stöbener, Marie Weinhart – 2021

Thermoresponsive coatings that exhibit “switch- able”protein- and cell-adhesive properties are frequently used for the fabrication of cell sheets. Among other architectures, polymer brush coatings have shown to be especially viable due to their distinct phase transition behavior, which can be tailored via a manifold of adjustable brush characteristics, such as the (co)- monomer composition, polymer chain length, and grafting density. Brush coatings based on poly(glycidyl ether)s (PGEs) have shown to efficiently mediate cell sheet fabrication when tethered to various tissue culture substrates. Herein, we report the phase transition of self-assembled PGE brushes with respect to polymer molecular weight (M: 10 and 22 kDa) and grafting density (0.07−0.5 chains nm−2) on gold model substrates studied by quasi-static QCM-D temperature ramp measurements. The brush grafting density can be tuned via the applied grafting conditions, and all brushes investigated feature broad phase transition regimes (ΔT ∼15 °C) with volume phase transition temperatures (VPTTs) close to the cloud point temperatures (CPTs) of the PGEs in solution. We further demonstrate that brush coatings with a low grafting density (0.07−0.12 chains nm−2) exhibit a continuous brush-to-mushroom transition, whereas brushes with medium grafting densities (0.3−0.5 chains nm−2) undergo a brush-to-brush transition comprising vertical phase separation during the phase transition progress. These insights help to understand the transition behavior of thin, thermoresponsive brushes prepared via grafting-to strategies and contribute to their rational design for improved functional surfaces.

Title
Grafting Density-Dependent Phase Transition Mechanism of Thermoresponsive Poly (glycidyl ether) Brushes: A Comprehensive QCM-D Study
Author
Alexander Schweigerdt, Silke Heinen, Daniel D Stöbener, Marie Weinhart
Publisher
Elsevier
Keywords
Coating materials, Sensors, Thermoresponsive polymers, Layers, Phase transitions
Date
2021-06-21
Identifier
https://doi.org/10.1021/acs.langmuir.1c00695
Source(s)
Citation
Langmuir 2021, Volume 37, Issue 23, 7087-7096.
Language
eng
Type
Text