TY - JOUR

T1 - Grafting Density-Dependent Phase Transition Mechanism of Thermoresponsive Poly(glycidyl ether) Brushes

T2 - A Comprehensive QCM-D Study

AU - Schweigerdt, Alexander

AU - Heinen, Silke

AU - Stöbener, Daniel D.

AU - Weinhart, Marie

N1 - Funding Information: A.S. is grateful to Dr. Anna Herrmann for proofreading and helpful comments during the manuscript preparation. We would like to acknowledge the assistance of the Core Facility BioSupraMol supported by the German Research Foundation (DFG). M.W. is grateful for financial support through the BMBF grant FKZ:13 N13523 and the FUB Focus Area NanoScale.

PY - 2021/6/15

Y1 - 2021/6/15

N2 - Thermoresponsive coatings that exhibit "switchable"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.

AB - Thermoresponsive coatings that exhibit "switchable"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.

UR - http://www.scopus.com/inward/record.url?scp=85108303909&partnerID=8YFLogxK

U2 - 10.1021/acs.langmuir.1c00695

DO - 10.1021/acs.langmuir.1c00695

M3 - Article

C2 - 34077209

AN - SCOPUS:85108303909

VL - 37

SP - 7087

EP - 7096

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 23

ER -